Chevrolet - Impala - Workshop Manual - 1995 - 1995

Page 921 Knock Sensor: Description and Operation PURPOSE: The Knock Sensor (KS) is used to detect engine detonation (ping). OPERATION A 5 volt reference is applied to the knock sensor which has an internal resistance of about 3900 ohms. This resistance will lower the applied voltage to about half or 2.5 volts. When a knock is present, a small AC voltage is produced by the knock sensor and transmitted to the control module riding on top of the already existing 2.5 volts. An AC voltage monitor inside the control module will detect the knock and trigger the control module to start retarding the spark incrementally. A control module (ECM or PCM) is used in conjunction with one or two knock sensors to control detonation. A KS module will be found on ECM applications. On PCM application no KS module will be found as it is internal to the control module. Diagram Information and Instructions Clutch Switch: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3044 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3845 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 792 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 2898 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Door Switch - Dome Light Stays On/Dead Battery/No Start Door Switch: Customer Interest Door Switch - Dome Light Stays On/Dead Battery/No Start File In Section: 8 - Chassis/Body Electrical Bulletin No.: 56-82-05 Date: September, 1995 Subject: Dome Lamp Stays On, Dead Battery, No Start (Shim Door Trim Panel Push Nail) Models: 1995 Chevrolet and GMC Truck C/K Models 1995 Topkick/Kodiak Models Condition Dome lamp stays on, with doors closed and headlight rotary wheel in the off position. Cause Dome lamp switch plunger is not pushed in far enough. There is too large a gap between the dome lamp switch plunger and the door panel convex push nail. Correction Shim out door panel push nail with color keyed shims available through GMSPO. Service Procedure Page 1093 5-Speed Manual Transmission W/4WD Page 919 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 2317 For K trucks with 8600 # GVW's and below, a new lower control arm is available featuring an opening under the front axle outboard boot (Figure 1). The opening should prevent the build-up of debris by allowing the debris to fall through. The new lower control arm went into production after the beginning of the 1995 model year starting with the VIN breakpoints listed above. Additionally, for vehicles operating in severe usage environments (snow plows, mines, etc.) a front axle seal cover is available and can be used in conjunction with the new lower control arm (Figure 2). The purpose of this protective device is to sweep as much debris as possible from the lower control arm. This should extend the life of the front axle seal. It should be noted however that the protective seal cover WILL, during its useful life, take on a ragged appearance while still adequately protecting the drive axle seal. The device is functioning as long as the fabric continues to sweep debris from the lower control arm. K - Models with GVW's Above 8600 # For K-models with GVW's above 8600 # a front axle seal cover is available (Figure 2). The purpose of this protective device is to sweep as much debris as possible from the lower control arm. This should extend the life of the front axle seal. It should be noted however that the protective seal cover WILL during its useful life, take on a ragged appearance while still adequately protecting the drive axle seal. The device is functioning as long as the fabric continues to sweep debris from the lower control arm. Page 3285 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 2883 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 211 Pinout Description: C2 (Part 1 Of 2) Pinout Description: C2 (Part 2 Of 2) Page 1259 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 11 Keyless Entry Module: Diagrams Keyless Entry Module (C1) Keyless Entry Module (C2) Page 525 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3014 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Engine - Intake Manifold Inspection/Replacement Intake Manifold: Technical Service Bulletins Engine - Intake Manifold Inspection/Replacement INFORMATION Bulletin No.: 00-06-01-026C Date: February 03, 2010 Subject: Intake Manifold Inspection/Replacement After Severe Internal Engine Damage Models: 2010 and Prior Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X Supercede: This bulletin is being revised to include additional model years. Please discard Corporate Bulletin Number 00-06-01-026B (Section 06 - Engine). When replacing an engine due to internal damage, extreme care should be taken when transferring the intake manifold to the new Goodwrench service engine long block. Internal damage may result in the potential discharge of internal engine component debris in the intake manifold via broken pistons and/or bent, broken, or missing intake valves. After removing the intake manifold from the engine, the technician should carefully inspect all of the cylinder head intake ports to see if the valve heads are still present and not bent. Usually when the valve heads are missing or sufficiently bent, internal engine component debris will be present to varying degrees in the intake port of the cylinder head. If this debris is present in any of the cylinder head intake ports, the intake manifold should be replaced. This replacement is required due to the complex inlet runner and plenum configuration of most of the intake manifolds, making thorough and complete component cleaning difficult and nearly impossible to verify complete removal of debris. Re-installation of an intake manifold removed from an engine with deposits of internal engine component debris may result in the ingestion of any remaining debris into the new Goodwrench service engine. This may cause damage or potential failure of the new service engine. Disclaimer Page 3846 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3220 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 556 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1106 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 2288 1992 LB4 VIN Z with "cold knock" only 1992-93 LB4 VIN Z with "cold knock" and installed field fix PROM OR with "cold knock" and detonation 1990-95 LB4 VIN Z Install check valve oil filter P/N 12555891 (FRAM PH3980). If the filter does not cure the condition, install the appropriate calibration from the tables (calibrations are available for all 1992 and some 1993 LB4 applications). If a calibration is not offered or does not cure the short duration cold knock Page 1262 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 90 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Heater Inlet Hose Heater Hose: Service and Repair Heater Inlet Hose Heater Hose Routing Quick Connect Heater Inlet Connector Remove or Disconnect Tool Required: J 38723 Heater Line Quick Connect Separator or Equivalent 1. Air cleaner. 2. Engine coolant. 3. Inlet hose mounting screw. 4. Inlet hose clamp at heater core. - Loosen the clamp enough to slide the clamp away from the fitting on the inlet hose 5. Inlet hose from heater core. 6. Push inlet hose into connector and insert J 38723 or equivalent into connector to release locking tabs. 7. Pull retainer and hose from heater inlet connector. Inspect - O-ring sealing surface on hose/pipe. Adjust - If replacing heater inlet connector, remove retainer from hose and discard, as new connector is equipped with retainer. Page 199 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3095 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Description and Operation Temperature Warning Lamp/Indicator: Description and Operation A bi-metal temperature switch located in the cylinder head controls the operation of a temperature indicator light. If the engine cooling system is not functioning properly and/or coolant temperature exceeds a predetermined value, the warning light will illuminate. Specifications Wheel Hub: Specifications Hub and Bearing Assembly To Steering Knuckle Bolts ....................................................................................................................... 180 Nm (133 ft. lbs.) Wheel Hub Bolts .................................................................................................................................. ................................................ 225 Nm (165 ft. lbs.) Page 436 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3322 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3544 Disclaimer Page 3163 Oxygen Sensor: Connector Locations HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 3933 Knock Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Harness View Engine Engine - GM dexos 1 and dexos 2(R) Oil Specifications Engine Oil: Technical Service Bulletins Engine - GM dexos 1 and dexos 2(R) Oil Specifications INFORMATION Bulletin No.: 11-00-90-001 Date: March 14, 2011 Subject: Global Information for GM dexos1(TM) and GM dexos2(TM) Engine Oil Specifications for Spark Ignited and Diesel Engines, Available Licensed Brands, and Service Fill for Adding or Complete Oil Change Models: 2012 and Prior GM Passenger Cars and Trucks Excluding All Vehicles Equipped with Duramax(TM) Diesel Engines GM dexos 1(TM) Information Center Website Refer to the following General Motors website for dexos 1(TM) information about the different licensed brands that are currently available: http://www.gmdexos.com GM dexos 1(TM) Engine Oil Trademark and Icons The dexos(TM) specification and trademarks are exclusive to General Motors, LLC. Only those oils displaying the dexos‹›(TM) trademark and icon on the front label meet the demanding performance requirements and stringent quality standards set forth in the dexos‹›(TM) specification. Look on the front label for any of the logos shown above to identify an authorized, licensed dexos 1(TM) engine oil. GM dexos 1(TM) Engine Oil Specification Important General Motors dexos 1(TM) engine oil specification replaces the previous General Motors specifications GM6094M, GM4718M and GM-LL-A-025 for most GM gasoline engines. The oil specified for use in GM passenger cars and trucks, PRIOR to the 2011 model year remains acceptable for those previous vehicles. However, dexos 1(TM) is backward compatible and can be used in those older vehicles. In North America, starting with the 2011 model year, GM introduced dexos 1(TM) certified engine oil as a factory fill and service fill for gasoline engines. The reasons for the new engine oil specification are as follows: - To meet environmental goals such as increasing fuel efficiency and reducing engine emissions. - To promote long engine life. - To minimize the number of engine oil changes in order to help meet the goal of lessening the industry's overall dependence on crude oil. dexos 1(TM) is a GM-developed engine oil specification that has been designed to provide the following benefits: - Further improve fuel economy, to meet future corporate average fuel economy (CAFE) requirements and fuel economy retention by allowing the oil to maintain its fuel economy benefits throughout the life of the oil. - More robust formulations for added engine protection and aeration performance. Page 3593 Spark Plug Diagnosis Page 923 Knock Sensor Circuit CIRCUIT DESCRIPTION The Knock Sensor (KS) system consist of a knock sensor with one wire that goes directly to the PCM. There is a check performed by the PCM. The check consist of monitoring CKT 496 for a voltage that is more than 0.04 volt and less than 4.6 volts. If the voltage is either too high or too low for 16 or more seconds, DTC 43 will set. CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic chart. 1. The first test is to determine if the system is functioning at the present time. 2. Test two determines the state of the 5 volt reference voltage applied to the knock sensor circuit. DIAGNOSTIC AIDS The PCM applies 5 volts to CKT 496. A 3900 ohm resistor in the knock sensor reduces the voltage to about 2.5 volts. When knock occurs, the knock sensor produces a small AC voltage that rides on top of the 2.5 volts already applied. An AC voltage monitor, in the PCM, is able to read this signal as knock and incrementally retard spark. If the KS system checks OK, but detonation is the complaint, refer to Diagnosis By Symptom / Detonation, Spark Knock See: Powertrain Management/Computers and Control Systems/Testing and Inspection/Symptom Related Diagnostic Procedures/Detonation/ Spark Knock Page 2646 Flushing Procedures using DEX-COOL(R) Important: The following procedure recommends refilling the system with DEX-COOL(R), P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M. This coolant is orange in color and has a service interval of 5 years or 240,000 km (150,000 mi). However, when used on vehicles built prior to the introduction of DEX-COOL(R), maintenance intervals will remain the same as specified in the Owner's Manual. ^ If available, use the approved cooling system flush and fill machine (available through the GM Dealer Equipment Program) following the manufacturer's operating instructions. ^ If approved cooling system flush and fill machine is not available, drain the coolant and dispose of properly following the draining procedures in the appropriate Service Manual. Refill the system using clear, drinkable water and run the vehicle until the thermostat opens. Repeat and run the vehicle three (3) times to totally remove the old coolant or until the drained coolant is almost clear. Once the system is completely flushed, refill the cooling system to a 50%-60% concentration with DEX‐COOL(R), P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M, following the refill procedures in the appropriate Service Manual. If a Service Manual is not available, fill half the capacity of the system with 100% DEX-COOL(R), P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M. Then slowly add clear, drinkable water (preferably distilled) to the system until the level of the coolant mixture has reached the base of the radiator neck. Wait two (2) minutes and reverify the coolant level. If necessary, add clean water to restore the coolant to the appropriate level. Once the system is refilled, reverify the coolant concentration using a Refractometer J 23688 (Fahrenheit scale) or J 26568 (centigrade scale) coolant tester, or equivalent. The concentration levels should be between 50% and 65%. Flushing Procedures using Conventional Silicated (Green Colored) Coolant Important: 2004-2005 Chevrolet Aveo (Pontiac Wave, Canada Only) does not use DEX‐COOL(R). The Aveo and Wave are filled with conventional, silicated engine coolant that is blue in color. Silicated coolants are typically green in color and are required to be drained, flushed and refilled every 30,000 miles (48,000 km). The Aveo and Wave are to be serviced with conventional, silicated coolant. Use P/N 12378560 (1 gal) (in Canada, use P/N 88862159 (1 L). Refer to the Owner's Manual or Service Information (SI) for further information on OEM coolant. Important: Do not mix the OEM orange colored DEX-COOL(R) coolant with green colored coolant when adding coolant to the system or when servicing the vehicle's cooling system. Mixing the orange and green colored coolants will produce a brown coolant which may be a customer dissatisfier and will not extend the service interval to that of DEX-COOL(R). Conventional silicated coolants offered by GM Service and Parts Operations are green in color. ^ If available, use the approved cooling system flush and fill machine (available through the GM Dealer Equipment Program) following the manufacturer's operating instructions. ^ If approved cooling systems flush and fill machine is not available, drain coolant and dispose of properly following the draining procedures in appropriate Service Manual. Refill the system using clear, drinkable water and run vehicle until thermostat opens. Repeat and run vehicle three (3) times to totally remove old coolant or until drained coolant is almost clear. Once the system is completely flushed, refill the cooling system to a 50%-60% concentration with a good quality ethylene glycol base engine coolant, P/N 12378560, 1 gal (in Canada, use P/N 88862159 1 L), conforming to GM specification 1825M, or recycled coolant conforming to GM specification 1825M, following the refill procedures in the appropriate Service Manual. If a Service Manual is not available, fill half the capacity of the system with 100% good quality ethylene glycol base (green colored) engine coolant, P/N 12378560 1 gal., (in Canada, use P/N 88862159 1 L) conforming to GM specification 1825M. Then slowly add clear, drinkable water (preferably distilled) to system until the level of the coolant mixture has reached the base of the radiator neck. Wait two (2) minutes and recheck coolant level. If necessary, add clean water to restore coolant to the appropriate level. Once the system is refilled, recheck the coolant concentration using a Refractometer J 23688 (Fahrenheit scale) or J 26568 (centigrade scale) coolant tester, or equivalent. Concentration levels should be between 50% and 65%. Parts Information Warranty Information Page 787 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 951 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 2476 Distributor: Testing and Inspection INSPECT 1. Distributor cap for cracks or tiny holes. Replace the cap if it is damaged or worn. 2. Metal terminals in the distributor cap for corrosion. Scrape them clean with a knife or replace the cap. 3. Rotor for wear or burning at the outer terminal. The presence of carbon on the terminal indicates rotor wear and the need for replacement. 4. Distributor shaft for shaft-to-bushing looseness. Insert the shaft in the distributor housing. If the shaft wobbles, replace the distributor housing and/or shaft. 5. Distributor housing for cracks or damage. MEASURE Tools Required J 24642-F Module Tester. Electrical performance of the module. The module can only be tested with an approved module tester, such as J 24642-F. Follow the directions that come with the tester. Page 576 Fuel Pump Oil Pressure Switch Page 3355 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Specifications Temperature Vs Resistance Value Page 795 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2469 plugs, or shorting of the leads to ground. The correct routing is shown in the image. Page 1311 Fig.2-Symbols (Part 2 Of 3) Page 3372 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 407 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1666 plugs, or shorting of the leads to ground. The correct routing is shown in the image. Page 2290 1993 to 1995 L05 VIN K Install the appropriate check valve oil filter P/N 25160561 (PF1218 for two-wheel C-series and P/N 12555891 (FRAM PH3980) for four-wheel drive K-series). If the oil filter does not cure the condition, install the appropriate calibration from the table (calibrations are available for some 1993 and 1994 L05 applications). All calibrations are for light duty vehicles equipped with 4L60-E (M30) transmissions (no heavy duty emission/4L80-E calibrations are available). If a calibration is not offered or does not cure the short duration cold knock condition, install the appropriate main bearings as determined by the procedure. 1990-94 L19 VIN N Page 1240 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3242 Throttle Position Sensor: Adjustments The Throttle Position (TP) Sensor is not adjustable. With the ignition "ON" and the engine stopped, the TPS voltage should be less than 0.85 volts. If more than 0.85 volts, the TPS must be replaced. Page 35 Keyless Entry Module: Diagrams Keyless Entry Module (C1) Keyless Entry Module (C2) Diagram Information and Instructions Vehicle Speed Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 204 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 2839 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 3578 plugs, or shorting of the leads to ground. The correct routing is shown in the image. Page 2828 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 440 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 481 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 293 Page 3298 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1035 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1168 Oil Pressure Switch (For Fuel Pump): Service and Repair Oil Pressure Switch REMOVE OR DISCONNECT 1. Electrical connector. 2. Oil pressure switch using wrench J 35748. INSTALL OR CONNECT 1. Oil pressure switch. 2. Electrical connector. Page 3700 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 755 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3516 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 961 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 2924 Air Flow Meter/Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3153 1995 G VAN 3A-72 Page 1166 Oil Pressure Switch Page 2190 condition, install the appropriate main bearings as determined by the following procedure. Calibration Information - 1992-93 LB4 VIN Z The revised PROMs reduce spark advance after the engine is started. The reduction in spark lowers the cylinder pressure and eliminates the knock. The revised PROMs will NOT eliminate a piston slap (Category C) or valve train noise (Category B) concern. The base cold knock PROM contains the previously released calibration updates. For 1992 LB4, the previous field release is included for torque converter clutch (TCC) lock up (see Bulletin 137107 - Chevrolet 92-75-7A; GMC Truck 92-7A-40; Oldsmobile 92-T-34; Canada 9274L60100) for automatic transmissions, or neutral gear rattle for manual transmissions (see Bulletin 267201R - Chevrolet 92-187B-7B; GMC Truck 92-7B-149A; Canada 93-7B-105). If a vehicle has had a detonation fix PROM installed previously, select the combined detonation and cold knock fix PROM for the application. See Bulletin 376508 for more information on field fix PROM for the application and detonation. Important: Use of a detonation fix PROM in a non-detonating vehicle may result in degraded driveability. GMSPO currently stocks three (3) PROMs for each light duty 1992 model year LB4 application. Base Cold Knock Fix Combination Cold Knock and Detonation Fix GMSPO Service Parts Assistance Center (SPAC 1-800-433-6961) will have information available on each PROM part number. Select the PROM from the table. Old Broadcast Code (Old B/C Code) and Scan I.D. information has been supplied to help installed previously. Use a TECH-1 to determine the Scan I.D. of the PROM in the vehicle or remove the PROM and read the Broadcast Code (B/C Code). If the B/C Code/Scan I.D. can be found in the first table, a detonation fix has not been installed. PROMs are currently available GMSPO. 1990-95 L05 VIN K Page 3287 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 1122 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2537 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 834 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3330 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2824 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Diagrams Engine Coolant Level Indicator Module Page 865 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 1845 Fluid - Differential: Technical Service Bulletins Drivetrain - Recommended Axle Lubricant File In Section: 0 - General Information Bulletin No.: 76-02-02A Date: October, 1998 INFORMATION Subject: Recommended Axle Lubricant Models: 1999 and Prior Rear Wheel Drive Passenger Cars, Light and Medium Duty Trucks, and Four Wheel Drive Vehicles This bulletin is being revised to add the 1998 and 1999 Model Years and add Vehicle Line and Recommended Axle Lubricant Information. Please discard Corporate Bulletin Number 76-02-02 (Section 0 - General Information). The following tables provide the latest information on recommended axle lubricant. Page 853 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 447 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3741 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3115 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1060 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 914 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 555 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 791 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 2542 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 652 Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 2466 Page 2346 Fuel Pump Oil Pressure Switch Page 3852 Engine Control Module: Description and Operation Powertrain Control Module (PCM) PURPOSE The Powertrain Control Module (PCM) is the control center of the fuel injection system. It constantly looks at the information from various sensors (inputs) and controls the systems (outputs) that affect vehicle performance. The control module also performs the diagnostics of the system. It can recognize operational problems, alert the driver through the Malfunction Indicator Lamp (MIL) "Service Engine Soon" light on the instrument panel and store a Diagnostic Trouble Code(s) (DTC) in the control module memory. The DTC identifies the problem areas to aid the technician in performing repairs. OPERATION The PCM is an electronic computer designed to process the various input information, and send the necessary electrical response to control fuel delivery, spark control, and other emission control systems. The control module can control these devices through the use of Quad Driver Modules (QDM). When the control module is commanding a device or a component "ON," the voltage potential of the output is "LOW" or near zero volts. When the control module is commanding a device or component "OFF," the voltage potential of the circuit will be "HIGH," or near 12 volts. The primary function of the QDM is to supply the ground for the component being controlled. The input information has an interrelation between sensor output. If one of the input devices failed, such as the oxygen sensor, this could affect more than one of the systems controlled by the computer. The PCM has two parts for service: - Controller which is the control module without the PROM (MEM-CAL). - PROM (Programmable Read Only Memory) which is a separate memory calibrator unit LEARNING ABILITY The PCM has a "learning" ability which allows it to make corrections for minor variations in the fuel system to improve driveability. If the battery is disconnected, to clear diagnostic trouble codes or for other repairs. The "learning" process resets and begins again. A change may be noted in the vehicle's performance. To "teach" the vehicle, ensure the engine is at operating temperature. The vehicle should be driven at part throttle, with moderate acceleration and idle conditions until normal performance returns. NOTE: The PCM must be maintained at a temperature below 85°C (185°F) at all times. This is most essential if the vehicle is put through a baking process. The control module will become inoperative if it's temperature exceeds 85°C (185°F). It is recommended that temporary insulation be placed around the control module during the time the vehicle is in a paint oven or other high temperature processes. Diagram Information and Instructions Fuel Pump Relay: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 789 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3344 Oil Pressure Switch Page 1547 ^ For 1995-97 vehicles, splice into CKT 241 (BRN) between connectors C120 and C100 (Figure 7). Notice: Connections must be water tight in order to prevent water from entering the circuit and causing damage to the components. 9. On K3 models, install the delay relay, included as part of the wiring harness kit, at the engine side of the bulkhead, adjacent to the existing relay. Mount the new relay with self-drilling fastener, P/N 22510339. Route and secure the relay wire harness behind the right oxygen sensor heat shield. 10. Verify system operation. When shifting the transfer case, you should hear the actuator motor operate. Important: Page 2751 Temperature Gauge: Testing and Inspection Gauge Reads High 1. Remove lead at sensor, measure resistance using an ohmmeter. 2. At 104 degrees F resistance should be approximately 1200-1350 ohms, and at 125 degrees F resistance should be approximately 53-55 ohms. 3. If resistance is not within specifications, replace sensor. 4. Disconnect lead at sensor and gauge, check for a high resistance using an ohmmeter. Repair wiring if necessary. Tires - Correct Inflation Pressure Information Tires: All Technical Service Bulletins Tires - Correct Inflation Pressure Information INFORMATION Bulletin No.: 00-00-90-002J Date: January 28, 2009 Subject: Information on Proper Tire Pressure Models: 2010 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2009 and Prior HUMMER H2, H3, H3T 2005-2009 Saab 9-7X Supercede: This bulletin is being revised to add model years and clarify additional information. Please discard Corporate Bulletin Number 00-00-90-002I (Section 00 - General Information). Important: ^ Adjustment of tire pressure for a customer with a Low Tire Pressure Monitor (TPM) light on and no codes in the TPM system is NOT a warrantable repair. Claims to simply adjust the tire pressure will be rejected. ^ ALL tires (including the spare tire) MUST be set to the recommended inflation pressure stated on the vehicle's tire placard (on driver's door) during the PRE-DELIVERY INSPECTION (PDI). Recommended inflation pressure is not the pressure printed on tire sidewall. ^ Tires may be over-inflated from the assembly plant due to the mounting process. ^ Generally a 5.6°C (10°F) temperature change will result in (is equivalent to) a 6.9 kPa (1 psi) tire pressure change. ^ 2008-2009 HUMMER H2 Only - The H2 comes standard with Light Truck "D" Load Range tires with a recommended cold inflation pressure of 289 kPa (42 psi). These tires will alert the driver to a low pressure situation at roughly 262 kPa (38 psi) due to a requirement in FMVSS 138 which specifies a Minimum Activation Pressure for each tire type. This creates a relatively narrow window of "usable" pressure values and the warning will be more sensitive to outside temperature changes during the colder months. As with other cold temperature/tire pressure issues, there is nothing wrong with the system itself. If a vehicle is brought in with this concern, check for tire damage and set all tires to the Recommended Cold Inflation Pressure shown on the vehicle placard. Accurate tire pressures ensure the safe handling and appropriate ride characteristics of GM cars and trucks. It is critical that the tire pressure be adjusted to the specifications on the vehicle¡C■s tire placard during PDI. Ride, handling and road noise concerns may be caused by improperly adjusted tire pressure. The first step in the diagnosis of these concerns is to verify that the tires are inflated to the correct pressures. The recommended tire inflation pressure is listed on the vehicle¡C■s tire placard. The tire placard is located on the driver¡C■s side front or rear door edge, center pillar, or the rear compartment lid. Tip ^ Generally a 5.6°C (10°F) temperature increase will result in (is equivalent to) a 6.9 kPa (1 psi) tire pressure increase. ^ The definition of a "cold" tire is one that has been sitting for at least 3 hours, or driven no more than 1.6 km (1 mi). ^ On extremely cold days, if the vehicle has been indoors, it may be necessary to compensate for the low external temperature by adding additional air to the tire during PDI. ^ During cold weather, the Tire Pressure Monitor (TPM) indicator light (a yellow horseshoe with an exclamation point) may illuminate. If this indicator turns off after the tires warm up (reach operating temperature), the tire pressure should be reset to placard pressure at the cold temperature. ^ The TPM system will work correctly with nitrogen in tires. ^ The TPM system is compatible with the GM Vehicle Care Tire Sealant but may not be with other commercially available sealants. Important: ^ Do not use the tire pressure indicated on the tire itself as a guide. Page 2827 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Wheels - Chrome Wheel Staining/Pitting/Corrosion Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Staining/Pitting/Corrosion INFORMATION Bulletin No.: 00-03-10-002F Date: April 21, 2011 Subject: Chemical Staining, Pitting, Corrosion and/or Spotted Appearance of Chromed Aluminum Wheels Models: 2012 and Prior GM Cars and Trucks Supercede: This bulletin is being revised to update model years, suggest additional restorative products and add additional corrosion information. Please discard Corporate Bulletin Number 00-03-10-002E (Section 03 - Suspension). Important You may give a copy of this bulletin to the customer. What is Chemical Staining of Chrome Wheels? Figure 1 Chemical staining in most cases results from acid based cleaners (refer to Figure 1 for an example). These stains are frequently milky, black, or greenish in appearance. They result from using cleaning solutions that contain acids on chrome wheels. Soap and water is usually sufficient to clean wheels. If the customer insists on using a wheel cleaner they should only use one that specifically states that it is safe for chromed wheels and does not contain anything in the following list. (Dealers should also survey any products they use during prep or normal cleaning of stock units for these chemicals.) - Ammonium Bifluoride (fluoride source for dissolution of chrome) - Hydrofluoric Acid (directly dissolves chrome) - Hydrochloric Acid (directly dissolves chrome) - Sodium Dodecylbenzenesulfonic Acid - Sulfamic Acid - Phosphoric Acid - Hydroxyacetic Acid Notice Many wheel cleaner instructions advise to take care to avoid contact with painted surfaces. Most customers think of painted surfaces as the fenders, quarter panels and other exterior sheet metal. Many vehicles have painted brake calipers. Acidic wheel cleaners may craze, crack, or discolor the paint on the brake calipers. Damage from wheel cleaners is not covered under the vehicle new car warranty. Soap and water applied with a soft brush is usually all that is required to clean the calipers. Whenever any wheel cleaner is used, it must be THOROUGHLY rinsed off of the wheel with clean, clear water. Special care must be taken to rinse under the hub cap, balance weights, wheel nuts, lug nut caps, between the wheel cladding and off the back side of the wheel. Wheels returned to the Warranty Parts Center (WPC) that exhibit damage from wheel cleaners most often have the damage around and under the wheel weight where the cleaner was incompletely flushed away. Notice Page 843 Temp Sensor Circuit Wiring Service and Repair Fuel Pressure Release: Service and Repair PROCEDURE: NOTE: A constant bleed feature in the pressure regulator relieves pressure when engine is turned "OFF." - Disconnect negative battery terminal to avoid possible fuel discharge if an accidental attempt is made to start the engine. - Loosen fuel filler cap to relieve tank vapor pressure. - The internal constant bleed feature of the TBI relieves fuel pump system pressure when the engine is turned "OFF." Therefore, NO further pressure relief procedure is required. Page 1266 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 815 Fig.2-Symbols (Part 2 Of 3) Specifications Manifold Absolute Pressure (MAP) Sensor: Specifications 1,000 to 2,000 Feet ............................................................................................................................. ........................................................... 3.6 to 5.2 Volts 2,000 to 3,000 Feet ........................................ ................................................................................................................................................ 3.5 to 5.1 Volts 3,000 to 4,000 Feet .............................................................................................................. .......................................................................... 3.3 to 5.0 Volts 4,000 to 5,000 Feet ......................... .............................................................................................................................................................. . 3.2 to 4.8 Volts 5,000 to 6,000 Feet .................................................................................................. ...................................................................................... 3.0 to 4.6 Volts 6,000 to 7,000 Feet ............. .............................................................................................................................................................. ............. 2.9 to 4.5 Volts 7,000 to 8,000 Feet ...................................................................................... .................................................................................................. 2.8 to 4.3 Volts 8,000 to 9,000 Feet . .............................................................................................................................................................. ......................... 2.6 to 4.2 Volts 9,000 to 10,000 Feet ........................................................................ .............................................................................................................. 2.5 to 4.0 Volts Page 1048 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3907 Idle Speed Control Actuator System ISC Actuator Circuit CIRCUIT DESCRIPTION The idle speed control actuator system assists the idle air control system in controlling the idle speed, primarily at cold temperatures. The idle speed control actuator is a vacuum operated device which opens the throttle slightly (2 to 3 degrees of angle) to increase the cold engine idle speed, to improve the mixing of the air and fuel, and to allow lower warmed up engine idle speeds. The idle speed control actuator is controlled by the idle speed control actuator solenoid, which is controlled by the control module. To increase the idle speed, the solenoid is turned "OFF," and no vacuum is routed to the idle speed control actuator, allowing it to open the throttle slightly. To decrease the idle speed, the solenoid is turned "ON," and vacuum is routed through the solenoid to the idle speed control actuator, allowing the throttle to fully close. In conjunction with the idle speed control actuator system, the idle air control system continuously monitors and controls the engine idle speed to the desired idle speed. A Tech 1 scan tool will read the control module commands to the idle speed control actuator system. CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic charts. 1. Checks to see if a vacuum source is present. 2. Checks to see if idle speed control actuator solenoid is commanded "ON." 3. Checks for power to the solenoid, the ground circuit, the connections at the idle speed control actuator solenoid and the solenoid itself. 4. Checks to see cause of no vacuum source. 5. Checks idle speed control solenoid and connections. Page 2967 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1154 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 1987 Tire Requisition & Return Document Campaign Identification Label/Claim Info. Each vehicle corrected in accordance with the instructions outlined in this Product Campaign Bulletin will require a "Campaign Identification Label". Each label provides a space to include the campaign number and the five (5) digit dealer code of the dealer performing the campaign service. This information may be inserted with a typewriter or a ball point pen. Each "Campaign identification Label" is to be located on the radiator core support in an area which will be visible when the vehicle is brought in by the Page 2877 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Ignition Firing Order Page 2244 Disclaimer Page 2738 Coolant Temperature Sensor/Switch (For Computer): Service and Repair Engine Coolant Temperature (ECT) Sensor NOTE: Care must be taken when handling engine coolant temperature sensor. Damage to the Engine Coolant Temperature (ECT) sensor will affect proper operation of the fuel injection system. REMOVAL 1. Disconnect negative battery cable. 2. Drain cooling system below level of sensor. 3. Disconnect electrical connector. 4. Remove ECT sensor. INSTALLATION 1. Install sensor in engine. 2. Connect electrical connector. 3. Refill cooling system. 4. Connect negative battery cable. Page 943 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 2619 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2388 Fuel Pump Oil Pressure Switch Page 1337 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 734 Horn Switch: Service and Repair Horn Pad Assembly Replacement REMOVAL Remove or disconnect the following: 1. Negative battery cable. 2. Pull four corners of horn pad from steering wheel. 3. Ground wire. 4. Horn wire assembly. INSTALLATION Install or connect the following: 1. Horn wire assembly. 2. Ground wire. 3. Push horn pad assembly on steering wheel. 4. Negative battery cable. Page 2816 Engine Control Module: Locations Powertrain Control Module (PCM) Wheels - Changing Procedures/Precautions Wheels: All Technical Service Bulletins Wheels - Changing Procedures/Precautions INFORMATION Bulletin No.: 06-03-10-010A Date: June 09, 2010 Subject: Information on Proper Wheel Changing Procedures and Cautions Models: 2011 and Prior GM Passenger Cars and Trucks 2010 and Prior HUMMER Models 2005-2009 Saab 9-7X 2005-2009 Saturn Vehicles Attention: Complete wheel changing instructions for each vehicle line can be found under Tire and Wheel Removal and Installation in Service Information (SI). This bulletin is intended to quickly review and reinforce simple but vital procedures to reduce the possibility of achieving low torque during wheel installation. Always refer to SI for wheel lug nut torque specifications and complete jacking instructions for safe wheel changing. Supercede: This bulletin is being revised to include the 2011 model year and update the available special tool list. Please discard Corporate Bulletin Number 06-03-10-010 (Section 03 Suspension). Frequency of Wheel Changes - Marketplace Driven Just a few years ago, the increasing longevity of tires along with greater resistance to punctures had greatly reduced the number of times wheels were removed to basically required tire rotation intervals. Today with the booming business in accessory wheels/special application tires (such as winter tires), consumers are having tire/wheel assemblies removed - replaced - or installed more than ever. With this increased activity, it opens up more of a chance for error on the part of the technician. This bulletin will review a few of the common concerns and mistakes to make yourself aware of. Proper Servicing Starts With the Right Tools The following tools have been made available to assist in proper wheel and tire removal and installation. - J 41013 Rotor Resurfacing Kit (or equivalent) - J 42450-A Wheel Hub Resurfacing Kit (or equivalent) Corroded Surfaces One area of concern is corrosion on the mating surfaces of the wheel to the hub on the vehicle. Excessive corrosion, dirt, rust or debris built up on these surfaces can mimic a properly tightened wheel in the service stall. Once the vehicle is driven, the debris may loosen, grind up or be washed away from water splash. This action may result in clearance at the mating surface of the wheel and an under-torqued condition. Caution Before installing a wheel, remove any buildup on the wheel mounting surface and brake drum or brake disc mounting surface. Installing wheels with poor metal-to-metal contact at the mounting surfaces can cause wheel nuts to loosen. This may cause a wheel to come off when the vehicle is moving, possibly resulting in a loss of control or personal injury. Whenever you remove the tire/wheel assemblies, you must inspect the mating surfaces. If corrosion is found, you should remove the debris with a die grinder equipped with a fine sanding pad, wire brush or cleaning disc. Just remove enough material to assure a clean, smooth mating surface. The J 41013 (or equivalent) can be used to clean the following surfaces: - The hub mounting surface - The brake rotor mounting surface - The wheel mounting surface Use the J 42450-A (or equivalent) to clean around the base of the studs and the hub. Lubricants, Grease and Fluids Page 2971 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 150 Underhood Fuse/Relay Center Page 722 Fog Lamp Switch Page 3179 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3583 Distributor: Specifications Distributor Hold Down Bolt .................................................................................................................. ................................................... 27 Nm (20 lbs. ft.) Page 1783 Notice: Cut through plastic case material only. Aluminum tubes are located approximately 1/8" behind the case wall (Figure 2, view 1). Do not use a larger diameter cutting wheel. 15. Using a heat gun to soften the plastic case, pull back the access door on the upper evaporator case carefully to prevent breaking the case. Reach in carefully and remove the holding clamp securing the capillary tube to the evaporator outlet tube. Be careful not to damage the capillary tube. Discard clamp. 16. Using a heat gun to soften the plastic case, pull back the access door on the lower evaporator case carefully to prevent breaking the case (Figure 2). Reach in carefully with two small adjustable wrenches and loosen the fitting attaching the TXV to the evaporator inlet tube. It will require a 7/8" crows foot extension to loosen the TXV outlet joint fitting hidden behind the TXV itself. Remove and discard the TXV. 17. Remove original O-rings from the evaporator tubes and replace with new O-rings that have been oiled with 525 viscosity refrigerant mineral oil. DO NOT USE PAG LUBRICANT. 18. Install the new TXV to the evaporator tubes being careful not to damage the O-rings. Finger tighten the joints and then torque the joints, using a backup wrench to hold the TXV in position to: INLET 20-35 Nm (14-25 lb.ft.) OUTLET 15-22 Nm (11-16 lb.ft.) Page 2957 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Manifold Absolute Pressure (MAP) Sensor Engine Page 265 Idle/Throttle Speed Control Unit: Service and Repair Throttle Body Assembly (Model 220) REMOVAL: - Remove the Idle Speed Control (ISC) Actuator and vacuum hose. - Remove ISC Actuator. INSTALLATION: - Install the ISC actuator and screws. - Connect vacuum hose. - Set activated idle speed. Refer to Adjustment Procedures. Page 3408 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 2547 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1570 Four Wheel Drive Selector Switch: Service and Repair 1. Disconnect battery ground cable, then remove console and slide shift boot up selector lever. 2. Disconnect switch harness at indicator assembly, then remove clip and switch. 3. Position new switch on mounting bracket and install attaching screw. Ensure shift lever assembly pawl is on switch contact carrier. 4. Route wiring as shown. 5. Install shift boot, console wiring harness and console, then connect battery ground cable. Page 101 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1566 Four Wheel Drive Selector Switch: Locations Transfer Case Switch (1 Ton) HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 1144 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 1404 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 2947 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 2552 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 862 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Specifications Valve Spring: Specifications Engine Liter/CID .................................................................................................................................. ........................................................... 7.4L/V8-454 All specifications given in inches. Free Length ......................................................................................................................................... ........................................................................... 2.12 Out Of Square Limit ......................................... .......................................................................................................................................................... 0.062 Installed Height .......................................................................................................................... ....................................................................... 1.766-1.828 Pressure, Lbs. @ Inches Closed Intake ................................................................................................................................................... ........................................... 74.0-86.0 @ 1.800 Exhaust ................................................................................................................................................ ........................................... 74.0-86.0 @ 1.800 Open Intake ................................................................................................................................................... ............................................... 195-215 @ 1.40 Exhaust ................................................................................................................................................ ............................................... 195-215 @ 1.40 Page 1965 2. Fill the injury (puncture) to keep moisture out. 3. Seal the inner liner with a repair unit to prevent air loss. External Inspection 1. Prior to demounting, inspect the tire surface, the valve and the wheel for the source of the leak by using a water and soap solution. Mark the injured area and totally deflate the tire by removing the valve core. 2. Demount the tire from the wheel and place the tire on a well-lighted spreader. Internal Inspection 1. Spread the beads and mark the puncture with a tire crayon. 2. Inspect the inner tire for any signs of internal damage. 3. Remove the puncturing object, noting the direction of the penetration. 4. Probe the injury with a blunt awl in order to determine the extent and direction of the injury. 5. Remove any loose foreign material from the injury. 6. Punctures exceeding 6.35 mm (1/4") should not be repaired. Cleaning 1. Clean the area around the puncture thoroughly with a proper liner cleaner, clean cloth and a scraper. This step serves to remove dirt and mold lubricants to insure proper adhesion and non-contamination of the buffing tool. 2. Refer to information on the product or manufacturer's Material Safety Data Sheet and follow guidelines for handling and disposal. Clean the Injury Channel Page 3406 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3133 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3431 Fig.2-Symbols (Part 2 Of 3) Page 3642 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 29 Important The following information MUST be documented on the repair order. Failure to do so may result in a chargeback. - Customer vehicle condition. - Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or Service Message. - Was a DTC(s) set? If yes, specify which DTC(s) were set. - After following the procedure contained within this bulletin, could the condition be duplicated? ‹› If the condition was not duplicated, then document the affected module/component connector name and number on the repair order. - If the condition was duplicated after the procedure contained within this bulletin was followed, and additional diagnosis led to the replacement of a module or component, the SI Document ID Number MUST be written on the repair order. Parts Information Alternate Distributor For All of North America Note NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada), specified for use to correct the condition in this bulletin. *We believe this source and their products to be reliable. There may be additional manufacturers of such products/materials. General Motors does not endorse, indicate any preference for, or assume any responsibility for the products or material from this firm or for any such items that may be available from other sources. Warranty Information (excluding Saab Models) For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon the module/component connection that the dielectric lubricant was applied to: Warranty Information (Saab Models) Page 3142 Manifold Absolute Pressure (MAP) Sensor: Description and Operation MAP Sensor PURPOSE The Manifold Absolute Pressure (MAP) sensor is a pressure sensitive variable resistor. It measures the changes in the intake manifold pressure which result from engine load and speed changes, and converts this to a voltage output. The computer uses this voltage output to control fuel delivery and ignition timing. OPERATION A closed throttle on engine coastdown would produce a relatively low MAP voltage output, while a wide open throttle would produce a high voltage output. Manifold absolute pressure is the OPPOSITE of vacuum. When manifold pressure is high, vacuum is low. The MAP sensor is also used to measure barometric pressure under certain conditions, which allows the control module to automatically adjust to different altitudes. The control module sends a 5 volt reference signal to the MAP sensor. As manifold pressure changes, electrical resistance of the sensor also changes. By monitoring the sensor output voltage, the control module knows the manifold pressure. A high pressure, low vacuum (high voltage) condition requires more fuel, while a low pressure, high vacuum (low voltage) requires less fuel. The control module used the MAP sensor to control fuel delivery and ignition timing. Page 1955 Refer to GM bulletin # 52-05-09 dated October, 1995 to obtain new tire(s) and for return of damaged tire(s). DO NOT ORDER TIRES FROM GMSPO. To obtain a tire(s) and to return damaged tire(s) to General, you will need to complete the General Motors Tire Requisition & Return Document (Figure 1). When completing the section "Reason for Tire Removal", you are to check off the bead box and in comments write campaign number 96-C-36. Customers will be notified of this campaign on their vehicles by General Motors (see copy of divisional customer letter(s) included with this bulletin). Dealer Campaign Responsibility All unsold new vehicles in dealers possession and subject to this campaign must be held and inspected/repaired per the service procedure of this Page 3849 Engine Control Module: Connector Views Engine Controls - Throttle Body Injection: C1 Pinout Description: C1 (Part 1 Of 2) Page 3054 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2524 Fig.1-Symbols (Part 1 Of 3) Page 1161 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Warranty - OE Chrome Plated Aluminum Wheel ID Wheels: All Technical Service Bulletins Warranty - OE Chrome Plated Aluminum Wheel ID File In Section: 03 - Suspension Bulletin No.: 99-03-10-102 Date: June, 1999 INFORMATION Subject: Original Equipment Chrome Plated Aluminum Wheel Identification Models: 1999 and Prior Passenger Cars and Light Duty Trucks Chrome plated aluminum wheels have been returned to the Warranty Parts Center that are not the original equipment (OE) components. Original equipment chrome plated aluminum wheels can be identified by either a balance weight clip retention groove (1) or a step (2) that is machined around both of the wheel's rim flanges. The rim flanges (3) of painted original equipment aluminum wheels do not have a groove or a step. Chrome plated aluminum wheels that do not have the wheel rim flange groove or step are aftermarket chrome plated components and are NOT warrantable. Any aftermarket chrome wheels received by the Warranty Parts Center will be charged back to the dealership. Page 1451 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 1120 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3960 Knock Sensor: Testing and Inspection Knock Sensor Check Page 3317 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 522 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3231 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Ignition Firing Order Page 845 Coolant Temperature Sensor/Switch (For Computer): Service and Repair Engine Coolant Temperature (ECT) Sensor NOTE: Care must be taken when handling engine coolant temperature sensor. Damage to the Engine Coolant Temperature (ECT) sensor will affect proper operation of the fuel injection system. REMOVAL 1. Disconnect negative battery cable. 2. Drain cooling system below level of sensor. 3. Disconnect electrical connector. 4. Remove ECT sensor. INSTALLATION 1. Install sensor in engine. 2. Connect electrical connector. 3. Refill cooling system. 4. Connect negative battery cable. Page 675 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 77 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3813 PCM Connector Pin-Out Page 1415 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 3289 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 953 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2278 Warranty Information Page 820 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3127 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1271 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 1008 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Capacity Specifications Engine Oil: Capacity Specifications TYPE.................................................................................................................................................... .......................................................................SG, SH CAPACITY, Refill: 6-cyl. 4.3L............................................................................................................... ........................................................................3.8 Liters* 4.0 Quarts* 8-cyl. 5.7L 1992-94.................. ...........................................................................................................................................................4. 7 Liters 5.0 Quarts Others................................................................................................................................................... .....................................3.8 Liters 4.0 Quarts 8-cyl. 7.4L: 1988-90.............................................................................................................................. ..............................................4.8 Liters 5.0 Quarts 1991-94................................................................................................................................................ .................................6.6 Liters* 7.0 Quarts* Others............................................................................. ...........................................................................................................5.7 Liters 6.0 Quarts Capacity shown is without filter. When replacing filter, additional oil may be added. *1992-93 C3500 models add an additional one (1) quart (0.95L) Above 40°F (4°C)...................................................... .........................................................................................................................................................30 ‡ Above 0°F (-18°C)................................................................................................................................ ...................................................................10W-30** Below 60°F (16°C)............................................ ............................................................................................................................................................5 W-30 **Preferred ‡May be used when other recommended viscosities are unavailable Page 876 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 770 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 2651 Heater Core: Service and Repair Rear AUXILLARY HEATER CORE Auxiliary Heater Module Remove or Disconnect 1. Engine coolant. 2. Rear quarter interior trim, as necessary. 3. Right rear quarter trim panel. 4. Right rear wheelhouse. 5. Auxiliary heater hoses from heater core. 6. Electrical connectors, as necessary. 7. Drain valve. 8. Bolts. 9. Nuts. 10. Heater module. 11. Blower motor, if necessary. 12. Heater case cover. 13. Heater core. Page 3898 Idle Air Control Valve: Service and Repair IAC Valve IAC Valve NOTE: The IAC valve is an electrical component and must not be soaked in any liquid cleaner or solvent. Otherwise damage could result. IMPORTANT: Thread-mounted IAC Valves have a dual taper, 10 mm diameter, pintle. The flange-mounted IAC valve and has a 12 mm diameter, dual taper pintle. Any replacement of an IAC valve must have the correct part number, with the appropriate pintle taper and diameter for proper seating of the valve in the throttle body. REMOVE OR DISCONNECT 1. Electrical connector. 2. IAC valve. ^ On thread-mounted units, use a 32 mm (1-1/4") wrench. ^ On flange-mounted units, remove screw assemblies. 3. IAC valve gasket or 0-ring and discard. CLEAN ^ Thread-mounted valve - Old gasket material from surface of throttle body assembly to insure proper seal of new gasket. ^ Flange-mounted valve - IAC valve surface on throttle body to assure proper seal of new 0-ring and contact of IAC valve flange. NOTE: If the IAC valve was removed during service, its operation may be tested electrically with the IAC system analyzer (J 37027 or BT- 8256K). However, if the valve pintle is extended electrically, it must also be retracted electrically. Before installing an IAC valve, measure the distance between the tip of the valve pintle and the mounting surface. If the dimension is greater than 28 mm (1.10"), it must be reduced to prevent damage to the valve. This may be done electrically using on IAC system analyzer motor tester (J 37027 or BT-8256K). MEASURE ^ Distance between tip of IAC valve pintle and mounting flange. If greater than 28 mm, use finger pressure to slowly retract the pintle. The force required to retract the pintle of a new valve will not cause damage to the valve. Page 852 Fig.2-Symbols (Part 2 Of 3) Page 82 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1985 Refer to GM bulletin # 52-05-09 dated October, 1995 to obtain new tire(s) and for return of damaged tire(s). DO NOT ORDER TIRES FROM GMSPO. To obtain a tire(s) and to return damaged tire(s) to General, you will need to complete the General Motors Tire Requisition & Return Document (Figure 1). When completing the section "Reason for Tire Removal", you are to check off the bead box and in comments write campaign number 96-C-36. Customers will be notified of this campaign on their vehicles by General Motors (see copy of divisional customer letter(s) included with this bulletin). Dealer Campaign Responsibility All unsold new vehicles in dealers possession and subject to this campaign must be held and inspected/repaired per the service procedure of this Page 3056 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3797 Harness Connector Faces Page 3295 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1679 Spark Plug: Application and ID Spark Plug Coding Spark Plug Codeing Legend DESCRIPTION Resistor-type, tapered-seat spark plugs are used on this engine. No gasket is used on these spark plugs. A dot before the spark plug code or the letter "C" after the number in the code indicates the spark plug has a copper core. Refer to Specification / Mechanical or to the vehicle emissions control information label for correct gap information. Page 1100 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1493 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 418 Coolant Temperature Sensor/Switch (For Computer): Service and Repair Engine Coolant Temperature (ECT) Sensor NOTE: Care must be taken when handling engine coolant temperature sensor. Damage to the Engine Coolant Temperature (ECT) sensor will affect proper operation of the fuel injection system. REMOVAL 1. Disconnect negative battery cable. 2. Drain cooling system below level of sensor. 3. Disconnect electrical connector. 4. Remove ECT sensor. INSTALLATION 1. Install sensor in engine. 2. Connect electrical connector. 3. Refill cooling system. 4. Connect negative battery cable. Page 3704 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3830 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 164 results from the alteration or modification of a vehicle using non-GM approved parts or accessories. Dealers should be especially cautious of accessory companies that claim the installation of their product will not void the factory warranty. Many times these companies have even given direction on how to quickly disassemble the accessory in an attempt to preclude the manufacturer from finding out that is has been installed. Any suspect repairs should be reviewed by the Fixed Operations Manager (FOM), and in Canada by the Warranty Manager (WM) for appropriate repair direction. If it is decided that a goodwill repair is to be made on the vehicle, even with the installation of such non-GM approved components, the customer is to be made aware of General Motors position on this issue and is to sign the appropriate goodwill documentation required by General Motors. It is imperative for dealers to understand that by installing such devices, they are jeopardizing not only the warranty coverage, but also the performance and reliability of the customer's vehicle. Disclaimer Page 2834 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3386 Throttle Position Sensor: Description and Operation TP Sensor PURPOSE: The Throttle Position (TP) sensor is connected to the throttle shaft on the throttle body unit. It is a potentiometer with one end connected to 5 volts from the control module and the other to ground. A third wire is connected to the control module to measure the voltage from the TP sensor. As the throttle valve angle is changed (accelerator pedal moved), the output of the TP sensor also changes. At a closed throttle position, the output of the TP signal is low (approximately 0.5 volt). As the throttle valve opens, the output increases so that, at Wide Open Throttle (WOT), the output voltage should be approximately 4.5 volts. By monitoring the output voltage from the TP sensor, the control module can determine fuel delivery based on throttle valve angle (driver demand). Page 2934 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 1501 Fluid Pressure Sensor/Switch: Electrical Diagrams Transmission Range (TR) Pressure Switch Assembly Circuit Check Transmission Range (TR) Pressure Switch Assembly Circuit Check Page 3324 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1018 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 404 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 563 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3143 Manifold Absolute Pressure (MAP) Sensor: Testing and Inspection Manifold Absolute Pressure (MAP) Output Check Page 1101 Vehicle Speed Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3268 VSS Signal Buffer Module - C/K Page 2825 Engine Control Module: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1255 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3713 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3778 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 684 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3387 Throttle Position Sensor: Testing and Inspection This check should be performed when TP sensor attaching parts have been replaced. A Tech 1 scan tool can be used to read the TP sensor output voltage, or: 1. Connect digital voltmeter J 39200 or equivalent, from TP sensor connector terminal "B" (BLK wire) to terminal "C" (DK BLU wire). 2. With ignition "ON," engine stopped, the TP sensor voltage should be less than 0.85 volt if more than 0.85 volt verify free throttle movement. If still more than 0.85 volt, replace TP sensor. 3. Remove the voltmeter and jumpers, reconnect the TP sensor connector to the sensor. Page 1378 The existing labor operation (E7200) has been changed to include "Add" conditions for cylinders that will not rotate. New Tumblers New tumblers are available from GMSPO for recoding lock cylinders that use double-sided reversible keys. These new tumblers should be used immediately and information about the disposition of original tumblers will be provided by GMSPO. Figure 1 shows the new tumbler profile. The shaded area was part of the original tumbler profile, and is removed on the new tumblers. The new part numbers for the tumblers are as follows: Part No. 2852732 = Tumbler # 1 Part No. 2852733 = Tumbler # 2 Part No. 2852734 = Tumbler # 3 Part No. 2852735 = Tumbler # 4 Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. New Procedures For Seized/Won't Rotate Column Mounted Ign. CYL. Page 2988 Coolant Temperature Sensor/Switch (For Computer): Locations Component View Engine Coolant Temperature (ECT) Sensor The Engine Coolant Temperature (ECT) Sensor is located on the intake manifold next to the thermostat housing. Page 3280 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3303 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 1568 Four Wheel Drive Selector Switch: Locations Transfer Case Switch (1/2 Ton, 3/4 Ton) HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 1237 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3388 Throttle Position Sensor: Adjustments The Throttle Position (TP) Sensor is not adjustable. With the ignition "ON" and the engine stopped, the TPS voltage should be less than 0.85 volts. If more than 0.85 volts, the TPS must be replaced. Page 3119 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Harness View Engine Page 682 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 1638 Disclaimer Page 909 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1267 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3746 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3934 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3891 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1492 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3364 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1871 procedures and short-cutting refrigerant recycling times. Use the following procedure for testing and correcting air contamination in your A/C service equipment. 1. Make certain that the ACR4 equipment has not been used for at least 12 hours. It is recommended that the equipment be left in an area where the temperature will remain constant overnight to allow the temperature of the refrigerant in the tank to stabilize. 2. Record the surrounding air temperature next to the ACR4 refrigerant tank. Important: A major assumption is that the ambient air temperature next to the tank represents the refrigerant temperature in the tank. Failure to take care in measuring the temperature could result in unnecessary work. 3. Close both liquid (blue) and vapor (red) valves on the ACR4 tank. 4. Disconnect low side (blue) service hose from the back of the ACR4. 5. Slowly disconnect the tank vapor hose (red) from the back of the ACR4 and connect it to the low side service port. 6. Open the vapor (red) valve on the tank and record the tank pressure on the low side gage. 7. Restore hoses to the original position. 8. Referring to the Table, find the ambient temperature measured in Step 2. Compare the pressure reading from Step 6 to the "maximum allowable pressure". If the pressure reading from Step 6 is less than the "maximum allowable pressure", no further action is necessary. Important: The closer the tank pressure is to the desired tank pressure, the better the A/C system will perform. 9. If the pressure reading from Step 6 exceeds the maximum allowable pressure from the Table, open both tank valves and operate the ACR4 through 4 or 5 evacuation cycles. This will activate the automatic air purge to lower the tank pressure. Important: Station should not be connected to vehicle. 10. Repeat the tank pressure checking procedure the next day to determine if the pressure has been reduced to acceptable levels. If the tank pressure has been reduced but is not acceptable, cycle with ACR4 through more evacuation cycles and recheck the next day. Continue process until acceptable pressure is obtained. If the tank pressure is not reduced through the evacuation cycling, then Kent-Moore should be contacted at 1-800-345-2233. Page 2505 Contamination Mixing conventional green coolant with DEX-COOL(R) will degrade the service interval from 5 yrs./150,000 miles (240,000 km) to 2 yrs./30,000 miles (50,000 km) if left in the contaminated condition. If contamination occurs, the cooling system must be flushed twice immediately and re-filled with a 50/50 mixture of DEX-COOL(R) and clean water in order to preserve the enhanced properties and extended service interval of DEX-COOL(R). After 5 years/150,000 miles (240,000 km) After 5 yrs/150,000 miles (240,000 km), the coolant should be changed, preferably using a coolant exchanger. If the vehicle was originally equipped with DEX-COOL(R) and has not had problems with contamination from non-DEX-COOL(R) coolants, then the service interval remains the same, and the coolant does not need to be changed for another 5 yrs/150,000 miles (240,000 km) Equipment (Coolant Exchangers) The preferred method of performing coolant replacement is to use a coolant exchanger. A coolant exchanger can replace virtually all of the old coolant with new coolant. Coolant exchangers can be used to perform coolant replacement without spillage, and facilitate easy waste collection. They can also be used to lower the coolant level in a vehicle to allow for less messy servicing of cooling system components. It is recommended that you use a coolant exchanger with a vacuum feature facilitates removing trapped air from the cooling system. This is a substantial time savings over repeatedly thermo cycling the vehicle and topping-off the radiator. The vacuum feature also allows venting of a hot system to relieve system pressure. Approved coolant exchangers are available through the GMDE (General Motors Dealer Equipment) program. For refilling a cooling system that has been partially or fully drained for repairs other than coolant replacement, the Vac-N-Fill Coolant Refill Tool (GE-47716) is recommended to facilitate removal of trapped air from the cooling system during refill. Disclaimer Page 190 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 513 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 1326 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 159 1994 Models: 1995 Models: Page 1036 Throttle Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3488 Fig.1-Symbols (Part 1 Of 3) Page 3377 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. DTC 45 (Rich Exhaust) Diagnostic Chart Revision Oxygen Sensor: Technical Service Bulletins DTC 45 (Rich Exhaust) Diagnostic Chart Revision File In Section: 6E - Engine Fuel & Emission Bulletin No.: 41-65-28 Date: October, 1994 SUBJECT: Section 3A - DTC 45 Rich Exhaust - Will Set When (Value Change) MODELS: 1994-95 Chevrolet and GMC Truck C/K, P Models, G Vans with 5.0L Engine (VIN H RPO LO3) 5.7L Engine (VIN K - RP0 LOS) - for 1994 under 8500 GVW 7.4L Engine (VIN N - RPO L19) This bulletin contains revisions to DTC 45 chart pages in the 1994-1995 G, C/K, P Truck "Driveability, Emissions and Electrical Diagnosis" manual as follows: Page 1052 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 297 Page 1180 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 952 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 709 1. Remove push nail from upper forward area of door panel (Figure 1). 2. Place shim on push nail stem (Figure 2). 3. Install push nail on door panel. Parts Information P/N Description Qty 15730041 Shim, Gray 1 15730042 Shim, Navy Blue 1 15730043 Shim, Ruby Red 1 Page 3321 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 2577 Maximum fan speed (air flow and related fan noise) through the engine compartment is experienced under two conditions. 1. When the vehicle sits in an unused condition for several hours, the viscous fluid within the thermostatic fan clutch assembly migrates and fully engages the clutch of the fan. After a short drive, the viscous fluid will migrate to the storage area in the fan clutch and the fan clutch will slip, reducing the noise (roar of the fan). This is normal thermostatic fan clutch operation. 2. When the engine is running, and the air being drawn by the fan or pushed through the radiator from the vehicle movement reaches a high enough temperature, the fan clutch will fully engage the fan clutch, drawing additional air through the radiator to lower the engine coolant temperature and A/C refrigerant temperature. When the cooling fan clutch fully engages, fan noise increases (for example; this is the same as switching an electric household fan from low to high speed). Some customers have interpreted this sound increase to be an increase in the engine RPM due to transmission downshift, transmission slipping, or TCC cycling. As the engine coolant temperature decreases, the fan clutch will begin to slip, lowering the actual speed of the fan blade and the resultant sound. Service Procedure When diagnosing an intermittent transmission downshift, slip, or busy/cycling TCC, follow these steps: 1. Verify the transmission fluid level and the fluid condition. Refer to the Automatic Transmission sub-section of the appropriate Service Manual. 2. Test drive the vehicle under the conditions described by the customer (ambient temperature, engine coolant temperature, trailering, etc.). It may be necessary to partially restrict airflow to the radiator in order to raise the engine coolant temperature to match the customer's conditions. 3. Monitor the engine RPM and the engine coolant temperature using a scan tool. 4. Listen for an actual increase in the engine RPM. Use either the vehicle tachometer (if equipped), the Tech 2 RPM or transmission slip speed as an indicator, rather than just the sound. If the engine RPM display on the tachometer or the Tech 2 increases, verify the scan tool RPM and coolant temperature readings. If the noise increase is due to the engagement of the fan, the engine RPM will not increase and the engine coolant temperature will begin to decrease after the fan engages. As the fan runs, the engine coolant temperature will drop and the fan will disengage, reducing noise levels. The engine RPM will not decrease. This cycle will repeat as the engine coolant temperature rises again. If the above procedure shows the condition to be cooling fan-related, no further action is necessary. The vehicle should be returned to the customer and the condition explained. If the above procedure shows the condition to be other than cooling fan-related, refer to the Automatic Transmission sub-section of the appropriate Service Manual for transmission diagnosis information. The following information regarding the operation of the engine cooling fan should be photocopied and given to the customer. Intermittent Transmission Downshift All light duty trucks are equipped with a thermostatic engine cooling fan. This fan is designed to provide greater fuel efficiency and quieter operation than a standard fan. These benefits are possible through the addition of a thermostatic clutch to the fan drive. When the engine is cool (it the engine has been run in the last few hours), the clutch allows the fan to "slip" or turn at a speed slower than the engine. By turning at a slower speed, the fan uses less horsepower, which saves fuel, and is quieter. When the engine temperature reaches a preset temperature or if the engine has not been run for several hours, the fan "engages" and turns at the same speed as the engine. "Engagement" of the fan provides increased airflow through the radiator to cool the engine. As the airflow increases, fan operation becomes clearly audible. This increase in noise can easily be mistaken for an increase in engine RPM and may be incorrectly blamed on the automatic transmission. When operating an unloaded vehicle in cooler ambient temperatures, the thermostatic clutch usually won't fully engage. However, if the vehicle is pulling a trailer, is heavily loaded or is operated at high ambient temperatures, the thermostatic fan clutch may cycle on and off as the engine coolant temperature rises and falls. The sound of fan operation under the conditions described above is a sign that the cooling system on your vehicle is working correctly. Replacement or modification of the cooling system or the transmission parts will not change or reduce the noise level. Attempts to reduce this noise may cause you, the customer, to believe that your vehicle is not reliable and will inconvenience you by causing your vehicle to be out of service. Page 700 Cargo Lamp Switch: Diagrams C212, C237, C302: Powerseat To Cross Body Harn, Rear Body Harn To Cross Body Harn, Body Harn To Cross Body Harn, Cargo Lamp Switch, Endgate Release Switch C411: Cross Body Harn To Cargo Lamp Harn Page 2357 Oil Pressure Warning Lamp/Indicator: Testing and Inspection The oil pressure warning light should go on when the ignition is turned on. If it does not light, disconnect the wire from the engine unit and ground the wire to the frame or cylinder block. Then if the warning light still does not go on, replace the bulb. If the warning light goes on when the wire is grounded, check the engine unit for a poor ground, or improper installation. (The presence of sealing compound on the threads of the engine unit will cause a poor ground.) If the unit is found to be properly grounded and installed, replace the unit. If the warning light remains lit when it normally should be out, replace the engine unit before proceeding to determine the cause for low pressure indication. The warning light will sometimes light or flicker when the engine is idling, even if oil pressure is adequate. However, the light should go out when the engine speed is increased. Page 2835 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 246 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1109 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Engine Controls - Aftermarket Accessory Usage Engine Control Module: Technical Service Bulletins Engine Controls - Aftermarket Accessory Usage INFORMATION Bulletin No.: 04-06-04-054B Date: November 18, 2010 Subject: Info - Non-GM Parts and Accessories (Aftermarket) Models: 2011 and Prior GM Passenger Cars and Trucks Supercede: This bulletin is being revised to add model years and update to the new U.S. Fixed Operation Manager (FOM) and Canada Warranty Manager (WM) names. Please discard Corporate Bulletin Number 04-06-04-054A (Section 06 - Engine/Propulsion System). The recent rise and expansion of companies selling non-GM parts and accessories has made it necessary to issue this reminder to dealers regarding GM's policy on the use and installation of these aftermarket components. When a dealer is performing a repair under the New Vehicle Limited Warranty, they are required to use only genuine GM or GM-approved parts and accessories. This applies to all warranty repairs, special policy repairs or any repairs paid for by GM. Parts and accessories advertised as being "the same" as parts manufactured by GM, but not sold through GM, do not qualify for use in warranty repairs, special policy repairs or any repairs paid for by GM. During a warranty repair, if a GM original equipment part is not available through GM Customer Care and Aftersales (GM CC&A;), ACDelco(R) distributors, other GM dealers or approved sources, the dealer is to obtain comparable, non-GM parts and clearly indicate, in detail, on the repair order the circumstances surrounding why non-GM parts were used. The dealer must give customers written notice, prior to the sale or service, that such parts or accessories are not marketed or warranted by General Motors. It should also be noted that dealers modifying new vehicles and installing equipment, parts and accessories obtained from sources not authorized by GM are responsible for complying with the National Traffic and Motor Vehicle Safety Act. Certain non-approved parts or assemblies, installed by the dealer or its agent not authorized by GM, may result in a change to the vehicle's design characteristics and may affect the vehicle's ability to conform to federal law. Dealers must fully understand that non-GM approved parts may not have been validated, tested or certified for use. This puts the dealer at risk for potential liability in the event of a part or vehicle failure. If a GM part failure occurs as the result of the installation or use of a non-GM approved part, the warranty will not be honored. A good example of non-authorized modification of vehicles is the result of an ever increasing supply of aftermarket devices available to the customer, which claim to increase the horsepower and torque of the Duramax(TM) Diesel Engines. These include the addition of, but are not limited to one or more of the following modifications: - Propane injection - Nitrous oxide injection - Additional modules (black boxes) that connect to the vehicle wiring systems - Revised engine calibrations downloaded for the engine control module - Calibration modules which connect to the vehicle diagnostic connector - Modification to the engine turbocharger waste gate Although the installation of these devices, or modification of vehicle components, can increase engine horsepower and torque, they may also negatively affect the engine emissions, reliability and/or durability. In addition, other powertrain components, such as transmissions, universal joints, drive shafts, and front/rear axle components, can be stressed beyond design safety limits by the installation of these devices. General Motors does not support or endorse the use of devices or modifications that, when installed, increase the engine horsepower and torque. It is because of these unknown stresses, and the potential to alter reliability, durability and emissions performance, that GM has adopted a policy that prevents any UNAUTHORIZED dealer warranty claim submissions to any remaining warranty coverage, to the powertrain and driveline components whenever the presence of a non-GM (aftermarket) calibration is confirmed - even if the non-GM control module calibration is subsequently removed. Refer to the latest version of Bulletin 09-06-04-026 (V8 Gas Engines) or 06-06-01-007 (Duramax(TM) Diesel Engines) for more information on dealer requirements for calibration verification. These same policies apply as they relate to the use of non-GM accessories. Damage or failure from the use or installation of a non-GM accessory will not be covered under warranty. Failure resulting from the alteration or modification of the vehicle, including the cutting, welding or disconnecting of the vehicle's original equipment parts and components will void the warranty. Additionally, dealers will NOT be reimbursed or compensated by GM in the event of any legal inquiry at either the local, state or federal level that Locations Heater Hose Routing Page 3269 Vehicle Speed Sensor: Connector Locations Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 1598 available, measurements may also be clearly and legibly handwritten into the Wheel Alignment Repair Order Questionnaire attached to this bulletin. 4. Attach the Wheel Alignment Repair Order Questionnaire below along with the print-out of "Before" and "After" wheel alignment measurements to the Repair Order and retain for use by GM. Wheel Alignment Equipment and Process Wheel alignments must be performed with a quality machine that will give accurate results when performing checks. "External Reference" (image-based camera technology) is preferred. Please refer to Corporate Bulletin Number 05-00-89-029B: General Motors Dealership Critical Equipment Requirements and Recommendations. Requirements: - Computerized four wheel alignment system. - Computer capable of printing before and after alignment reports. - Computer capable of time and date stamp printout. - Racking system must have jacking capability - Racking system must be capable of level to 1.6 mm (1/16 in) - Appropriate wheel stops and safety certification - Built-in turn plates and slip plates - Wheel clamps capable of attaching to 20" or larger wheels - Racking capable of accepting any GM passenger car or light duty truck - Operator properly trained and ASE-certified (U.S. only) in wheel alignment Recommendations: Racking should have front and rear jacking capability. Equipment Maintenance and Calibration: Alignment machines must be regularly calibrated in order to give correct information. Most manufacturers recommend the following: - Alignment machines with "internal reference" sensors should be checked (and calibrated, if necessary) every six months. - Alignment machines with "external reference" (image-based camera technology) should be checked (and calibrated, if necessary) once a year. - Racks must be kept level to within 1.6 mm (1/16 in). - If any instrument that is part of the alignment machine is dropped or damaged in some way, check the calibration immediately. Check with the manufacturer of your specific equipment for their recommended service/calibration schedule. Wheel Alignment Process When performing wheel alignment measurement and/or adjustment, the following steps should be taken: Preliminary Steps: 1. Verify that the vehicle has a full tank of fuel (compensate as necessary). 2. Inspect the wheels and the tires for damage. 3. Inspect the tires for the proper inflation and irregular tire wear. 4. Inspect the wheel bearings for excessive play. 5. Inspect all suspension and steering parts for looseness, wear, or damage. 6. Inspect the steering wheel for excessive drag or poor return due to stiff or rusted linkage or suspension components. 7. Inspect the vehicle trim height. 8. Compensate for frame angle on targeted vehicles (refer to Wheel Alignment Specifications in SI). Satisfactory vehicle operation may occur over a wide range of alignment angles. However, if the wheel alignment angles are not within the range of specifications, adjust the wheel alignment to the specifications. Refer to Wheel Alignment Specifications in SI. Give consideration to excess loads, such as tool boxes, sample cases, etc. Follow the wheel alignment equipment manufacturer's instructions. Measure/Adjust: Important Prior to making any adjustments to wheel alignment on a vehicle, technicians must verify that the wheel alignment specifications loaded into their wheel alignment machine are up-to-date by comparing these to the wheel alignment specifications for the appropriate model and model year in SI. Using incorrect and/or outdated specifications may result in unnecessary adjustments, irregular and/or premature tire wear and repeat customer concerns Page 3010 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Harness View Engine Page 621 Rear Door Jamb Switch Wiring Page 515 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3035 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 967 Manifold Absolute Pressure (MAP) Sensor: Service and Repair MAP Sensor REMOVE OR DISCONNECT: 1. Negative battery cable. 2. EVAP Vacuum harness assembly. 3. Electrical connector releasing locking tab. 4. Bolts or release lock tabs and remove sensor. INSTALL OR CONNECT: 1. Bolts or snap sensor on bracket. 2. Electrical connector. 3. EVAP Vacuum harness. 4. Negative battery cable. Page 1083 Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 96 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Wheels/Tires - Tire Radial Force Variation (RFV) Wheels: Customer Interest Wheels/Tires - Tire Radial Force Variation (RFV) INFORMATION Bulletin No.: 00-03-10-006F Date: May 04, 2010 Subject: Information on Tire Radial Force Variation (RFV) Models: 2011 and Prior GM Passenger Cars and Light Duty Trucks 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X 2000-2005 Saturn L Series 2003-2007 Saturn ION Supercede: This bulletin is being revised to considerably expand the available information on Radial Force Variation (RFV) and should be reviewed in whole. Please discard Corporate Bulletin Number 00-03-10-006E (Section 03 - Suspension). Important - Before measuring tires on equipment such as the Hunter GSP9700, the vehicle MUST be driven a minimum of 16 km (10 mi) to ensure removal of any flat-spotting. Refer to Corporate Bulletin Number 03-03-10-007E - Tire/Wheel Characteristics of GM Original Equipment Tires. - Equipment such as the Hunter GSP9700 MUST be calibrated prior to measuring tire/wheel assemblies for each vehicle. The purpose of this bulletin is to provide guidance to GM dealers when using tire force variation measurement equipment, such as the Hunter GSP9700. This type of equipment can be a valuable tool in diagnosing vehicle ride concerns. The most common ride concern involving tire radial force variation is highway speed shake on smooth roads. Tire related smooth road highway speed shake can be caused by three conditions: imbalance, out of round and tire force variation. These three conditions are not necessarily related. All three conditions must be addressed. Imbalance is normally addressed first, because it is the simpler of the three to correct. Off-vehicle, two plane dynamic wheel balancers are readily available and can accurately correct any imbalance. Balancer calibration and maintenance, proper attachment of the wheel to the balancer, and proper balance weights, are all factors required for a quality balance. However, a perfectly balanced tire/wheel assembly can still be "oval shaped" and cause a vibration. Before balancing, perform the following procedures. Tire and Wheel Diagnosis 1. Set the tire pressure to the placard values. 2. With the vehicle raised, ensure the wheels are centered on the hub by loosening all wheel nuts and hand-tightening all nuts first by hand while shaking the wheel, then torque to specifications using a torque wrench, NOT a torque stick. 3. Visually inspect the tires and the wheels. Inspect for evidence of the following conditions and correct as necessary: - Missing balance weights - Bent rim flange - Irregular tire wear - Incomplete bead seating - Tire irregularities (including pressure settings) - Mud/ice build-up in wheel - Stones in the tire tread - Remove any aftermarket wheels and/or tires and restore vehicle to original condition prior to diagnosing a smooth road shake condition. 4. Road test the vehicle using the Electronic Vibration Analyzer (EVA) essential tool. Drive for a sufficient distance on a known, smooth road surface to duplicate the condition. Determine if the vehicle is sensitive to brake apply. If the brakes are applied lightly and the pulsation felt in the steering wheel increases, refer to the Brakes section of the service manual that deals with brake-induced pulsation. If you can start to hear the vibration as a low boom noise (in addition to feeling it), but cannot see it, the vehicle likely has a first order (one pulse per propshaft revolution) driveline vibration. Driveline first order vibrations are high enough in frequency that most humans can start to hear them at highway speeds, but are too high to be able to be easily seen. These issues can be caused by driveline imbalance or misalignment. If the vehicle exhibits this low boom and the booming pulses in-and-out on a regular basis (like a throbbing), chances are good that the vehicle could have driveline vibration. This type Page 866 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Park/Neutral Position and Backup Lamp Switch Transmission Position Switch/Sensor: Locations Park/Neutral Position and Backup Lamp Switch HD Electronic 4-Speed Automatic Overdrive Transmission Page 3136 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 916 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 257 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3953 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 459 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 375 Wheel Speed Sensor: Service and Repair FRONT WHEEL SPEED SENSOR REPLACEMENT REMOVE OR DISCONNECT 1. Tire and wheel. 2. Brake Caliper. 3. Rotor. 4. Sensor wire mounting clip on the control arm. 5. Sensor wire mounting clip on the frame. 6. Sensor electrical connector. ^ Clean Area Thoroughly IMPORTANT: The speed sensor mounts into a bore that leads to the center of the sealed bearing. Use caution when cleaning and working around the bore. Do not contaminate the lubricant inside the sealed bearing. Failure to do so can lead to premature bearing failure. 7. Sensor from hub and bearing assembly. NOTICE: Carefully remove the sensor by pulling it straight out of the bore. DO NOT use a screwdriver, or other device, to pry the sensor out of the bore. Prying will cause the sensor body to break off In the bore. INSTALL OR CONNECT IMPORTANT: The new speed sensor will have a new 0-ring. Dispose of the old 0-ring. Lubricate the new 0-ring lightly with bearing grease prior to installation. You may also lubricate the sensor just above and below the 0-ring. DO NOT lubricate the bore. 1. Sensor into hub and bearing assembly. TIGHTEN ^ Sensor mounting bolt to 18 Nm (13 lbs. ft.). IMPORTANT: The new speed sensor has new mounting clips already installed on the wire. DO NOT reuse the old clips. 2. Sensor electrical connector. 3. Sensor wire mounting clip to the frame rail. 4. Sensor wire mounting clip to the control arm. 5. Rotor. 6. Brake caliper. 7. Tire and wheel. Page 2179 1993 to 1995 L05 VIN K Install the appropriate check valve oil filter P/N 25160561 (PF1218 for two-wheel C-series and P/N 12555891 (FRAM PH3980) for four-wheel drive K-series). If the oil filter does not cure the condition, install the appropriate calibration from the table (calibrations are available for some 1993 and 1994 L05 applications). All calibrations are for light duty vehicles equipped with 4L60-E (M30) transmissions (no heavy duty emission/4L80-E calibrations are available). If a calibration is not offered or does not cure the short duration cold knock condition, install the appropriate main bearings as determined by the procedure. 1990-94 L19 VIN N Page 3888 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3906 ISC Check Page 3073 Knock Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Diagram Information and Instructions Throttle Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 910 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Service and Repair Rocker Arm Assembly: Service and Repair Rocker arm studs that have damaged threads may be replaced with standard studs. Loose studs should be replaced with 0.003 inch or 0.013 inch oversize studs which are available for replacement. The rocker arm studs are threaded into the cylinder head. Unscrew studs to remove damaged/ worn studs. Coat threads on cylinder head end of stud with sealer before assembling to head. Specifications Compression Check: Specifications Minimum, 698 kPa (100 psi) @ 200 rpm. The lowest cylinder reading should not be less than 80% of the highest. Perform compression test with engine at normal operating temperature, spark plugs removed and throttle wide open. Locations Engine Page 752 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 1904 Fuse: Locations Lower LH side of I/P Page 902 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 2212 Piston: Service and Repair Pistons & Rods Assemble Fig. 9 Piston & Ring End Gap Orientation Assemble pistons to connecting rods, locating piston ring end gaps as shown in Fig. 9. Lubricate piston rings with clean engine oil. Without disturbing the piston ring end gap location, install piston. Piston must be installed with notch in piston facing front of engine. A 0.001 inch oversize piston is available for service use to obtain proper clearances for slightly worn cylinder bores that require only light honing. In addition, oversizes of 0.020 inch, 0.030 inch and 0.040 inch are available. If the cylinders have less than 0.005 inch taper or wear, they can be reconditioned with a hone and fitted with the 0.001 inch oversize piston. Connecting rod bearing inserts are available in standard size and undersizes of 0.001 inch, 0.002 inch, 0.010 inch and 0.020 inch. The bearings can be replaced without removing the rod assembly by removing the cap and replacing the upper and lower halves of the bearing. Page 2243 2. Remove the serpentine belt from the accessory drive system. 3. Install the tool onto the power steering pulley. Position the legs of the tool into the outer grooves of the pulley, farthest from the front of the engine. 4. Install the retaining cord around the pulley and to the legs of the tool. 5. Put on the laser safety glasses provided with the tool. 6. Depress the switch on the rear of the tool to activate the light beam. 7. Rotate the power steering pulley as required to project the light beam onto the crankshaft balancer pulley grooves. 8. Inspect for proper power steering pulley alignment. - If the laser beam projects onto the second rib or raised area (1), the pulleys are aligned properly. - If the laser beam projects more than one-quarter rib 0.9 mm (0.035 in) mis-alignment, adjust the position of the power steering pulley as required. - Refer to SI for Power Steering Pulley Removal and Installation procedures. 9. Install the serpentine belt to the accessory drive system in the original orientation. 10. Operate the vehicle and verify that the belt noise concern is no longer present. Tool Information Please visit the GM service tool website for pricing information or to place your order for this tool. Page 1499 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 497 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 512 Cruise Control Switch: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1151 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1394 Neutral Safety Switch: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 2940 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 2004 degradation. Important Regardless of the inflation media for tires (atmospheric air or nitrogen), inflation pressure maintenance of tires is critical for overall tire, and ultimately, vehicle performance. Disclaimer Door Master Power Window Switch, LH LH Door Master Power Window Switch Wheels/Tires - Use of Nitrogen Gas in Tires Tires: All Technical Service Bulletins Wheels/Tires - Use of Nitrogen Gas in Tires INFORMATION Bulletin No.: 05-03-10-020C Date: April 27, 2010 Subject: Use of Nitrogen Gas in Tires Models: 2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 05-03-10-020B (Section 03 - Suspension). GM's Position on the Use of Nitrogen Gas in Tires General Motors does not oppose the use of purified nitrogen as an inflation gas for tires. We expect the theoretical benefits to be reduced in practical use due to the lack of an existing infrastructure to continuously facilitate inflating tires with nearly pure nitrogen. Even occasional inflation with compressed atmospheric air will negate many of the theoretical benefits. Given those theoretical benefits, practical limitations, and the robust design of GM original equipment TPC tires, the realized benefits to our customer of inflating their tires with purified nitrogen are expected to be minimal. The Promise of Nitrogen: Under Controlled Conditions Recently, nitrogen gas (for use in inflating tires) has become available to the general consumer through some retailers. The use of nitrogen gas to inflate tires is a technology used in automobile racing. The following benefits under controlled conditions are attributed to nitrogen gas and its unique properties: - A reduction in the expected loss of Tire Pressure over time. - A reduction in the variance of Tire Pressures with temperature changes due to reduction of water vapor concentration. - A reduction of long term rubber degradation due to a decrease in oxygen concentrations. Important These are obtainable performance improvements when relatively pure nitrogen gas is used to inflate tires under controlled conditions. The Promise of Nitrogen: Real World Use Nitrogen inflation can provide some benefit by reducing gas migration (pressure loss) at the molecular level through the tire structure. NHTSA (National Highway Traffic Safety Administration) has stated that the inflation pressure loss of tires can be up to 5% a month. Nitrogen molecules are larger than oxygen molecules and, therefore, are less prone to "seeping" through the tire casing. The actual obtainable benefits of nitrogen vary, based on the physical construction and the materials used in the manufacturing of the tire being inflated. Another potential benefit of nitrogen is the reduced oxidation of tire components. Research has demonstrated that oxygen consumed in the oxidation process of the tire primarily comes from the inflation media. Therefore, it is reasonable to assume that oxidation of tire components can be reduced if the tire is inflated with pure nitrogen. However, only very small amounts of oxygen are required to begin the normal oxidation process. Even slight contamination of the tire inflation gas with compressed atmospheric air during normal inflation pressure maintenance, may negate the benefits of using nitrogen. GM Tire Quality, Technology and Focus of Importance Since 1972, General Motors has designed tires under the TPC (Tire Performance Criteria) specification system, which includes specific requirements that ensure robust tire performance under normal usage. General Motors works with tire suppliers to design and manufacture original equipment tires for GM vehicles. The GM TPC addresses required performance with respect to both inflation pressure retention, and endurance properties for original equipment tires. The inflation pressure retention requirements address availability of oxygen and oxidation concerns, while endurance requirements ensure the mechanical structure of the tire has sufficient strength. This combination has provided our customers with tires that maintain their structural integrity throughout their useful treadlife under normal operating conditions. Regardless of the inflation media for tires (atmospheric air or nitrogen), inflation pressure maintenance of tires is critical for overall tire, and ultimately, vehicle performance. Maintaining the correct inflation pressure allows the tire to perform as intended by the vehicle manufacturer in many areas, including comfort, fuel economy, stopping distance, cornering, traction, treadwear, and noise. Since the load carrying capability of a tire is related to inflation pressure, proper inflation pressure maintenance is necessary for the tire to support the load imposed by the vehicle without excessive structural Page 1329 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2533 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3415 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 251 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2622 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1858 The dexos (TM) specification and trademarks are exclusive to General Motors, LLC. Only those oils displaying the dexos (TM) trademark and icon on the front label meet the demanding performance requirements and stringent quality standards set forth in the dexos (TM)specification. Look on the front label for any of the logos shown above to identify an authorized, licensed dexos 2(TM) engine oil. GM dexos 2(TM) Engine Oil Specification - dexos 2(TM) is approved and recommended by GM for use in Europe starting in model year 2010 vehicles, regardless of where the vehicle was manufactured. - dexos 2(TM) is the recommended service fill oil for European gasoline engines. Important The Duramax(TM) diesel engine is the exception and requires lubricants meeting specification CJ-4. - dexos 2(TM) is the recommended service fill oil for European light-duty diesel engines and replaces GM-LL-B-025 and GM-LL-A-025. - dexos 2(TM) protects diesel engines from harmful soot deposits and is designed with limits on certain chemical components to prolong catalyst life and protect expensive emission reduction systems. It is a robust oil, resisting degradation between oil changes and maintaining optimum performance longer. Disclaimer Page 1156 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3451 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 458 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 237 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 653 Backup Lamp Switch: Locations Manual Transmission HD 5-Speed Manual Transmission 5-Speed Manual Transmission Page 1228 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 1489 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 535 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Specifications Spark Plug Wire: Specifications RESISTANCE VALUES 0-15 inch cable .................................................................................................................................... ....................................... 3,000 - 10,000 ohms. 15-25 inch cable .................................................................................................................................. ....................................... 4,000 - 15,000 ohms. 25-35 inch cable .................................................................................................................................. ....................................... 6,000 - 20,000 ohms. NOTE: Longer wires should measure about 5,000 to 10,000 ohms per foot. Page 3183 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3784 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3222 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3370 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Capacity Specifications Refrigerant: Capacity Specifications REFRIGERANT-134A Pickup Models ..................................................................................................................................... .................................................... 0.91 kg (2.0 lb.) Crew Cab Suburban and Utility Models Front A/C only ........................................................................................................................ 1.02 kg (2.25 lb) Suburban with Rear Air Conditioning ....................................................................................................................................................... 1.81 kg (4.0 lb) - Overcharging a system may allow liquid Refrigerant-134a to get into the compressor, causing compressor noise and damage. Undercharging will cause insufficient cooling. Page 346 11. Install either the original sensor or a new one in the hub and secure the sensor. Ensure that the sensor is seated flush against the hub. 12. Install the rotor, the caliper and the wheel. 13. Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel by hand. The voltage should now read at least 350 ACmV's. Parts Information Warranty Information For vehicles repaired under warranty, use the table. Disclaimer Harness View Engine Locations Blower Motor Relay: Locations HIGH FRONT BLOWER RELAY Heater And Air Conditioning Wiring The High Front Blower Relay is located under Instrument Panel (I/P), on top of Heating Ventilation Air Conditioning (HVAC) plenum. Page 383 Coolant Temperature Sensor/Switch (For Computer): Locations Component View Engine Coolant Temperature (ECT) Sensor The Engine Coolant Temperature (ECT) Sensor is located on the intake manifold next to the thermostat housing. Page 1314 Knock Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 2462 Timing Mark Valve Clearance Specifications Valve Clearance: Specifications Valve Clearance Specifications Engine Liter/CID .................................................................................................................................. ........................................................... 7.4L/V8-454 All specifications given in inches. Stem Diameter Std. Intake ................................................................................................................................................... ...................................................... 0.3715-0.3722 Exhaust ................................................................ ...................................................................................................................................... 0.3715-0.3722 Maximum Tip Refinish ......................................................................................................................... ........................................................................ [03] Face Angle .......................................................... ....................................................................................................................................................... 45 deg. Margin [01] Intake ................................................................................................................................................... .................................................................. 0.0315 Exhaust ................................................................. .................................................................................................................................................. 0.0315 Valve Lash ........................................................................................................................................... ........................................................................... [06] [01] Minimum. [03] Grind only enough to provide true surface. After grinding valve stems, ensure sufficient clearance remains between rocker arm & valve spring cap or rotator. [06] Torque rocker arm bolt to 40 ft. lbs Page 901 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 302 Disclaimer Page 3190 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1805 Brake Fluid: Specifications Brake System DOT 3 Diagram Information and Instructions Knock Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1929 Underhood Fuse/Relay Center Page 2049 of vibration is normally felt more in the "seat of the pants" than the steering wheel. 5. Next, record the Hertz (Hz) reading as displayed by the EVA onto the tire data worksheet found at the end of this bulletin. This should be done after a tire break-in period of at least 16 km (10 mi) at 72 km/h (45 mph) or greater, in order to eliminate any possible tire flat-spotting. This reading confirms what the vehicle vibration frequency is prior to vehicle service and documents the amount of improvement occurring as the result of the various steps taken to repair. Completing the Steering Wheel Shake Worksheet below is required. A copy of the completed worksheet must be saved with the R.O. and a copy included with any parts returned to the Warranty Parts Center for analysis. A reading of 35 to 50 Hz typically indicates a first order propshaft vibration. If this is the situation, refer to Corporate Bulletin Number 08-07-30-044D. Generally, a reading between 10 and 20 Hz indicates a tire/wheel vibration and if this is the reading obtained, continue using this bulletin. If the tire 1st order vibration goes away and stays away during this evaluation, the cause is likely tire flat-spotting. Tire flat-spotting vibration may come and go at any speed over 72 km/h (45 mph) during the first 10 minutes of operation, if vibration continues after 10 minutes of driving at speeds greater than 72 km/h (45 mph), tire flat-spotting can be ruled out as the cause for vibration. 6. If flat-spotting is the cause, provide the explanation that this has occurred due to the vehicle being parked for long periods of time and that the nature of the tire is to take a set. Refer to Corporate Bulletin Number 03-03-10-007E: Information on Tire/Wheel Characteristics (Vibration, Balance, Shake, Flat Spotting) of GM Original Equipment Tires. 7. If the road test indicates a shake/vibration exists, check the imbalance of each tire/wheel assembly on a known, calibrated, off-car dynamic balancer.Make sure the mounting surface of the wheel and the surface of the balancer are absolutely clean and free of debris. Be sure to chose the proper cone/collet for the wheel, and always use the pilot bore for centering. Never center the wheel using the hub-cap bore since it is not a precision machined surface. If any assembly calls for more than 1/4 ounce on either rim flange, remove all balance weights and rebalance to as close to zero as possible. If you can see the vibration (along with feeling it) in the steering wheel (driving straight without your hands on the wheel), it is very likely to be a tire/wheel first order (one pulse per revolution) disturbance. First order disturbances can be caused by imbalance as well as non-uniformities in tires, wheels or hubs. This first order frequency is too low for a human to hear, but if the amplitude is high enough, it can be seen. If a vibration or shake still exists after balancing, any out of round conditions, of the wheel, and force variation conditions of the tire, must be addressed. Equipment such as the Hunter GSP9700 can address both (it is also a wheel balancer). Tire radial force vibration (RFV) can be defined as the amount of stiffness variation the tire will produce in one revolution under a constant load. Radial force variation is what the vehicle feels because the load (weight) of the vehicle is always on the tires. Although free runout of tires (not under load) is not always a good indicator of a smooth ride, it is critical that total tire/wheel assembly runout be within specification. Equipment such as the Hunter GSP9700 loads the tire, similar to on the vehicle, and measures radial force variation of the tire/wheel assembly. Note that the wheel is affecting the tire's RFV measurement at this point. To isolate the wheel, its runout must be measured. This can be easily done on the Hunter, without the need to set up dial indicators. If the wheel meets the runout specification, the tire's RFV can then be addressed. After measuring the tire/wheel assembly under load, and the wheel alone, the machine then calculates (predicts) the radial force variation of the tire. However, because this is a prediction that can include mounting inaccuracies, and the load wheel is much smaller in diameter than used in tire production, this type of service equipment should NOT be used to audit new tires. Rather, it should be used as a service diagnostic tool to minimize radial force variation of the tire/wheel assembly. Equipment such as the Hunter GSP9700 does an excellent job of measuring wheel runout, and of finding the low point of the wheel (for runout) and the high point of the tire (for radial force variation). This allows the tire to be matched mounted to the wheel for lowest tire/wheel assembly force variation. The machine will simplify this process into easy steps. The following assembly radial force variation numbers should be used as a guide: When measuring RFV and match mounting tires perform the following steps. Measuring Wheel Runout and Assembly Radial Force Variation Important The completed worksheet at the end of this bulletin must be attached to the hard copy of the repair order. - Measure radial force variation and radial runout. - If a road force/balancing machine is used, record the radial force variation (RFV) on the worksheet at the end of this bulletin. It may be of benefit to have the lowest RFV assembly to the front left corner. If the machine is not available and the EVA data suggests there is an issue, swap the tire and wheel assemblies from the front to the back. Re-check on the EVA and if the problem still exists, test another vehicle to find tires that do not exhibit the same frequency and swap those tires onto the subject vehicle. - If a runout/balancing machine is used, record the radial runout of the tire/wheel assemblies on the worksheet at the end of this bulletin. If one or more of the tire/wheel assemblies are more than.040 in (1.02 mm), match mount the tire to the wheel to get below.040 in (1.02 mm). For sensitive customers, readings of 0.030 inch (0.76 mm) or less are preferable, it may also be of benefit to have the lowest runout assembly to the front left corner. If the machine is not available and the EVA data suggests there is an issue, swap the tire and wheel assemblies from the front to the back. Re-check on the EVA and if the problem still exists, test another vehicle to find tires that do not exhibit the same frequency and swap those tires Page 495 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3002 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Brakes - Low Speed (Below 5 MPH) ABS Activation Wheel Speed Sensor: Customer Interest Brakes - Low Speed (Below 5 MPH) ABS Activation Bulletin No.: 02-05-25-006B Date: January 05, 2006 TECHNICAL Subject: Antilock Brake (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface) Models: 1999-2000 Cadillac Escalade 1995-1999 Chevrolet Silverado (Old Style) 1995-2000 Chevrolet Suburban, Tahoe (Old Style) 1995-2003 Chevrolet Astro Van, Blazer, S10 1995-1999 GMC Sierra (Old Style) 1995-2000 GMC Yukon, Yukon XL (Old Style) 1995-2001 GMC Envoy, Jimmy 1995-2003 GMC Safari Van, Sonoma 1995-2001 Oldsmobile Bravada Supercede: This bulletin is being revised to update the correction and warranty information. Please discard Corporate Bulletin Number 02-05-25-006A (Section 05 - Brakes). Condition Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set. Cause The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface. Correction Measure AC voltage and clean wheel speed sensor mounting surfaces. 1. Raise the vehicle on a hoist. 2. Disconnect both the front wheel speed sensor harness connectors. 3. Place a DVM across the terminals of each sensor connector. 4. Rotate the wheel with hand speed and measure the ACmV's. The reading should be at least 350 ACmV's. 5. If the reading is between 200 and 350 ACmV's, remove the wheel, caliper and rotor in order to gain access to the speed sensor. 6. Remove the wheel speed sensor and plug the hole to prevent debris from falling into the hub during service. 7. Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery cloth, ScotchBrite(TM) or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion. 8. Check the sensor head to determine if it has been warped/distorted due to the corrosion build up or other causes. Check the mounting surface on the sensor head for flatness by placing it on the edge of a metal machinists scale or other suitable straight edge to measure the flatness. Check the sensor for flatness in multiple (minimum 3) positions/directions. If the sensor head is distorted, replace the sensor. 9. Apply (spray) two thin coats of the specified rust penetrating lubricant (corrosion inhibitor) to the complete sensor mounting surface on the bearing hub. Allow to dry for 3-5 minutes between coats. Use ONLY Rust Penetrating Lubricant, P/N 89022217 (Canadian P/N 89022218). 10. When the corrosion inhibitor is dry to the touch (about 10 minutes), apply a thin layer of bearing grease to the hub surface and sensor 0-ring prior to sensor installation. Use ONLY Wheel Bearing Lubricant, P/N 01051344 (Canadian P/N 993037). Page 1784 19. Pull back access door on the upper evaporator case carefully to prevent breaking the case (Figure 1). Align the TXV capillary against the evaporator outlet tube being sure not to damage the capillary line. Place the first holding clamp so it is located 1/4" or less below the crimp in the capillary tube (Figure 3). Install the second clamp 1/4" or less below the first clamp. Be sure the clamps are fully seated on the tube and that the capillary is retained in the formed seat of each clamp (Figure 3, Section 1-1). Notice: After all components are installed, evacuate and charge the A/C system. Leak test all joints that were opened. 20. Using a heat gun to soften the plastic case, close both access doors and align the edges of the plastic. Using a soldering gun, melt both edges of the case together along the full length of the cuts, as smoothly as possible. 21. Cover the soldered closures with duct tape to prevent air leakage. 22. Reinstall the right side trim panel, the D-pillar trim, the C-pillar trim, the C-pillar seat belt retainer and the rear bench seat. Page 3913 Idle/Throttle Speed Control Unit: Service and Repair Throttle Body Assembly (Model 220) REMOVAL: - Remove the Idle Speed Control (ISC) Actuator and vacuum hose. - Remove ISC Actuator. INSTALLATION: - Install the ISC actuator and screws. - Connect vacuum hose. - Set activated idle speed. Refer to Adjustment Procedures. Engine - Overheating Diagnostic Tip Fan Shroud: Technical Service Bulletins Engine - Overheating Diagnostic Tip FILE IN SECTION: 6 - Engine BULLETIN NO.: 56-62-01 DATE: July, 1995 SUBJECT: Engine Overheat Resulting from Repositioning Fan in Shroud MODELS: 1990-95 Chevrolet and GMC Truck Light & Medium Duty Trucks Excluding Vans and Sport Utilities Auxiliary engine belt-driven equipment is often added to commercially owned trucks. Most service personnel recognize the potential effect this can have on water pump bearing loading. An often overlooked concern that can result from installing auxiliary belt driven equipment is the loss of some cooling system performance if the fan is repositioned fore or aft from its original factory installed position within the fan shroud. The fore/aft location of the fan within the shroud has a direct effect on how efficiently air is drawn through the radiator. A change in this relationship will often result in a report of reduced cooling system performance and possible engine overheat. Diagnosis of this type concern should start with simply asking the owner if the problem was noted prior to the installation of the auxiliary equipment. If possible, temporarily remove the add-on equipment and install the fan to its original location within the shroud and determine if this corrects the cooling problem. In some cases, a different OEM shroud and/or fan may be available that compensates for the revised placement of the fan with the added equipment. Stationary operation of engine or transmission driven equipment should be preceded by chocking the wheels and raising the hood (particularly in hot weather) to allow hot air that could be trapped under the hood of a running parked truck to escape. Page 3832 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3448 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 3812 PCM Connector Pin-Out Page 2991 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3658 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3193 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2800 1994 Models: 1995 Models: Page 88 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 2544 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 850 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3055 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 2920 Fig.1-Symbols (Part 1 Of 3) Page 2849 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 1277 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. A/T - 4L80-E 2nd Gear only After A Cold Start/DTC 87 Control Module: Customer Interest A/T - 4L80-E 2nd Gear only After A Cold Start/DTC 87 Bulletin No.: 67-71-53B Date: November 10, 2003 TECHNICAL Subject: No Upshift/2nd Gear Only After Cold Start-Intermittent DTC 87-High Ratio Error (Replace EPROM) Models: 1994-1995 Chevrolet and GMC C, K, P Truck, G Van 1996 Chevrolet and GMC P Truck, G Van Equipped with HYDRA-MATIC 4L80E Automatic Transmission (RPO MT1) Supercede: This bulletin is being revised to correct the electronic formatting. There have been no changes to the content of the bulletin. Please discard Corporate Bulletin Number 67-71-53A (Section 7 Transmission). Condition Some owners may comment about no transmission upshift after a cold start. In conjunction, Diagnostic Trouble Code (DTC) 87 is setting intermittently causing the PCM to command the default action of second gear only. Cause The commanded shift to third gear or fourth gear has taken longer than 2 seconds with a minimum 25% TP Sensor reading which has caused DTC 87 to set. Correction If normal diagnostics fail to lead to a resolution or the condition cannot be duplicated, replace the EPROM. Service Information/Procedure Check the PCM for a current or history DTC 87. If DTC 87 is present, refer to the appropriate Service Manual for diagnosis of DTC 87. Refer to corporate bulletin # 577115 for additional information on diagnosing DTC 87. If the diagnosis fails to lead to a resolution and DTC 87 only sets after a cold start, replace the EPROM. Refer to the appropriate Service Manual for EPROM replacement. It is a good idea to verify the new EPROM I.D. with a scan tool against the application listed below. The service EPROM raises the DTC 87 shift time parameter to 4 seconds and the code enabling temperature to 20°C (68°F). Page 3120 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3212 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1145 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3696 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Diagram Information and Instructions Manifold Absolute Pressure (MAP) Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3277 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3334 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 438 Brake Switch (Cruise Control): Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 2560 Radiator Cooling Fan Motor: Service and Repair Fig. 33 Auxiliary Cooling Fan Replacement Refer to Fig. 33 for auxiliary cooling fan replacement. Page 1476 Fluid Pressure Sensor/Switch: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 2966 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3853 Engine Control Module: Service and Repair Fuel Module (Located Above Blower Motor Assembly) Replacement of the Powertrain Control Module (PCM) consists of a service controller, without a PROM (MEM-CAL). If the diagnostic procedures require the PCM to be replaced, the PCM, PROM (MEM-CAL) should be checked for the correct part number. If they are correct, remove the PROM (MEM-CAL), and install them in the control module. The control module will not contain a PROM (MEM-CAL). IMPORTANT: When replacing a production PCM with a control module, transfer the broadcast code and production PCM part number to the control module label. Do not record information on the access cover. NOTE: The ignition must be "OFF," and disconnect negative battery cable when disconnecting or reconnecting the PCM connector, to prevent internal damage to the PCM. NOTE: To prevent possible Electrostatic Discharge damage to the PCM, Do Not touch the connector pins or soldered components on the circuit board. REMOVE OR DISCONNECT 1. Negative battery cable. 2. Glove box. 3. PCM harness connectors. 4. PCM from tray. 5. Mounting brackets and modules if equipped. 6. Access cover PROM (MEM-CAL). INSTALL OR CONNECT 1. PROM (MEM-CAL) access cover in new PCM. 2. Mounting brackets and modules if equipped. 3. PCM into tray until clips lock. 4. PCM harness connectors. 5. Glove box. 6. Negative battery cable. 7. Perform functional check. Page 1753 EXAMPLE 2: The lower insert is stamped STD (standard) and the upper is stamped 0.0010". The undersize for a STD bearing is 0. Divide 0 by 2 to get 0. Divide 0.0010" by 2 to get 0.0005". Add 0 and 0.0005" together to calculate the bearing undersize, which is 0.0005" in this case. 13. Add the original bearing undersize calculated in step 12 to the clearance measured and written down in step 9. For example, if a clearance of 0.0030" was measured with plastigage in step 9 and the calculated bearing undersize from step 12 was 0.0005", the bearing clearance for that particular main journal is equal to 0.0030" plus 0.0005". The bearing clearance would be 0.0035" in this case. 14. Determine which of the combinations of two sizes of replacement bearings will produce the desired clearance. The two sizes available are 0.001" and 0.002". One insert of each size may be combined to produce an intermediate undersize of 0.0015". Subtract the replacement bearing size from the actual clearance to determine which bearing should be used. The bearing that should be used is the one which gives a clearance closer to 0.0008" than to 0.0028". The clearance must not be less than 0.0008". Using the example from step 11, the actual clearance is 0.0035". Subtracting 0.001" from 0.0035" will give a clearance of 0.0025", just barely within the required range. Subtracting 0.002" from 0.0035" will give a clearance of 0.0015". The 0.002" undersize bearing set would be the one to use in this case since it gives a clearance closer to 0.0008", but not less. 15. Install the replacement upper main bearing insert using tool J 8080. 16. Install the replacement lower main bearing insert in the main bearing cap. Lay a piece of plastigage across the width of the lower main bearing insert (same as step 5). 17. Repeat steps 7, 8 and 9. 18. Measuring the plastigage with the scale on the envelope, verify the clearance of the replacement bearings is within the range of 0.001" to 0.003". 19. Repeat steps 4 through 16 for each main bearing. 20. Thrust the crankshaft forward and backward several times to seat the thrust bearing. 21. Reinstall oil pump; torque to 88 N.m (65 lb ft). 22. Reinstall the oil pan and other hardware. 23. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 24. Install fuel pump fuse, start engine, check for leaks or unusual noises. 25. Road test vehicle, check for leaks or unusual noises. THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE OUT OF THE VEHICLE Recommended for K, S and T vehicles. 1. Remove the engine from the vehicle using the appropriate service manual procedure. 2. Mount the engine on an engine stand, flip the engine so the oil pan is facing up. 3. Remove the oil pan. 4. Remove the oil pump and shield. 5. Remove the dipstick tube. 6. Remove one (1) main bearing cap (must do one at a time). 7. Plasti-gage bearing. 8. If the bearing clearance is out of specification (clearance greater than 0.003 inches), remove upper main bearing from the block. 9. Check the size of the original bearing. 10. Determine what combination of new bearings are required to get the clearance in the acceptable range of 0.0008 inches to 0.0028 inches. See steps Page 3052 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 455 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 1126 Vehicle Speed Sensor: Description and Operation Vehicle Speed Sensor (Manual Transmission) Vehicle Speed Sensor (2WD) Vehicle Speed Sensor (4WD) PURPOSE: The Vehicle Speed Sensor (VSS) is made up of a coil mounted on the transmission and a tooth rotor mounted to the output shaft in the transmission. As each rotor tooth nears the coil, the coil produces an AC voltage pulse. As the vehicle speed increases the number of AC voltage pulses per second increases. The vehicle speed signal buffer processes inputs from the VSS and output signal to the speedometer, control module, and cruise control module. The VSS buffer signal takes the voltage pulses from the VSS and uses them to open and close four solid state output switches to ground at a rate proportional to vehicle speed. The VSS buffer is matched to the vehicle based on final drive ratio and tire size. It is important to ensure that the correct VSS buffer is installed in the vehicle if replacement is necessary. Page 3410 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3675 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 1595 Verify Original Equipment Condition of the Vehicle - Verify that Original Equipment Tires and Wheels or Official GM Accessory Tires and Wheels are on the vehicle. - Verify that aftermarket suspension "Lift" or "Lowering" Kits or other suspension alterations have NOT been done to the vehicle. - Check for accidental damage to the vehicle; for example, severe pothole or curb impacts, collision damage that may have affected the wheel alignment of the vehicle; e.g., engine cradles, suspension control arms, axles, wheels, wheel covers, tires may show evidence of damage/impact. - Check to be sure vehicle has seen "Normal Use" rather than abuse; e.g., very aggressive driving may show up by looking at the tires and condition of the vehicle. - Check for other additional equipment items that may significantly affect vehicle mass such as large tool boxes, campers, snow plow packages (without the snowplow RPO), etc., especially in trucks and cutaway/incomplete vehicles. Significant additional mass can affect trim height and wheel alignment of the vehicle and may necessitate a customer pay wheel alignment when placed semi-permanently in the vehicle (Upfitter instructions are to realign the vehicle after placement of these types of items. (This typically applies to trucks and incomplete vehicles that can be upfit with equipment such as the above.) Customer Concerns, "Normal Operation" Conditions and "Mileage Policy" Possible Concerns The following are typical conditions that may require wheel alignment warranty service: 1. Lead/Pull: defined as "at a constant highway speed on a typical straight road, the amount of effort required at the steering wheel to maintain the vehicle's straight heading." Important Please evaluate for the condition with hands-on the steering wheel. Follow the "Vehicle Leads/Pulls" diagnostic tree located in SI to determine the cause of a lead/pull concern. Lead/Pull concerns can be due to road crown or road slope, tires, wheel alignment or even in rare circumstances a steering gear issue. Lead/pull concerns due to road crown are considered "Normal Operation" and are NOT a warrantable condition -- the customer should be advised that this is "Normal Operation." Important Some customers may comment on a "Lead/Pull" when they hold the steering wheel in a level condition. If so, this is more likely a "steering wheel angle" concern because the customer is "steering" the vehicle to obtain a "level" steering wheel. 2. Steering wheel angle to the left or right (counter-clockwise or clockwise, respectively): Defined as the steering wheel angle (clocking) deviation from "level" while maintaining a straight heading on a typical straight road. 3. Irregular or Premature tire wear: Slight to very slight "feathering" or "edge" wear on the shoulders of tires is NOT considered unusual and should even out with a tire rotation; if the customer is concerned about a "feathering" condition of the tires, the customer could be advised to rotate the tires earlier than the next scheduled mileage/maintenance interval (but no later than the next interval). Be sure to understand the customer's driving habits as this will also heavily influence the tire wear performance; tire wear from aggressive or abusive driving habits is NOT a warrantable condition. Important Slight or mild feathering, cupping, edge or heel/toe wear of tire tread shoulders is "normal" and can show up very early in a tire/vehicle service mileage; in fact, some new tires can show evidence of feathering from the factory. These issues do NOT affect the overall performance and tread life of the tire. Dealer personnel should always check the customer's maintenance records to ensure that tire inflation pressure is being maintained to placard and that the tires are being rotated (modified-X pattern) at the proper mileage intervals. Wheel alignments are NOT to be performed for the types of "Normal" Tire Feathering shown in Figures 1-4 below. Page 1211 Throttle Position Sensor: Service and Repair Throttle Position (TP) Sensor NOTE: Since TP configurations can be mounted interchangeably, be sure to order the correct one for your engine with the identical part number of the one being replaced. REMOVE OR DISCONNECT 1. Electrical connector. 2. Two TP sensor attaching screw assemblies. 3. TP sensor from throttle body assembly. NOTE: The TP sensor is an electrical component and must not be soaked in any liquid cleaner or solvent, as damage may result. INSTALL OR CONNECT 1. With throttle valve in normally closed position, install TP sensor on throttle shaft and rotate counter clockwise to align mounting hole. 2. TP sensor attaching screw assemblies, precoated with appropriate thread.locking compound. Tighten Screw assemblies to 2.0 Nm (18.0 lb. in.). 3. Electrical connector. 4. Check for TP sensor output as follows: ^ Connect scan tool scanner to read TP sensor output voltage. ^ With ignition "ON" and engine stopped, TP sensor voltage should be less than 0.85 volt. If more than 0.85 volt, replace TP sensor. Page 874 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 231 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3199 Oxygen Sensor: Testing and Inspection VISUAL INSPECTION: - Connectors and wires - Housing and insulator for cracks/damage - Sensor tip for silicone contamination (white powdery coating) PERFORMANCE TEST: Checks working range and response (speed). - Warm engine - Install DVOM between sensor and ground (2 volt D.C. range) - "RUN" engine at steady cruise speed (about 2500 rpm) Voltage should vary at least eight times in ten seconds between 0.2 and 0.8 volts (normal range). - Drive system rich: The use of a properly adjusted propane flow-meter (J-26911) is industry standard. Voltage should increase to at least 0.8 volts within two to three seconds. - Drive system lean: Create a vacuum leak from a source that is not an ECM input or output. Voltage should drop to at least 0.3 volts within two to three seconds. NOTE: After each test the O2 sensor should return to normal operating range within two to three seconds. - O2 Sensor should be replaced for failure to pass any of the tests above. NOTE: A CEC system that is operating excessively rich or lean will drive the 02 sensor to its maximum range and should be repaired first and not diagnosed as a 02 sensor failure. - Reconnect all hoses and electrical connectors. Clear all codes set and retrain idle. Page 247 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 549 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 1754 12 through 14 in the "in-vehicle" service outlined above. 11. Reinstall the upper main bearing. 12. Reinstall the main cap and lower bearing; torque to 110 N.m (80 lb ft). 13. Repeat for each main bearing. 14. Reinstall oil pump and shield; torque to 88 N.m (65 lb ft). 15. Reinstall dipstick tube. 16. Reinstall oil pan. 17. Reinstall engine in vehicle. 18. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 19. Install fuel pump fuse, start engine, check for leaks or unusual noises. 20. Road test vehicle, check for leaks or unusual noises. Correction Category B: Valve Train Clatter, Tick or Click For 1992-94 vehicles equipped with a 4.3L V6 (LB4 VIN Z or L35 VIN W) engine see Corporate Bulletin 376006 for information on converting from net lash to adjustable lash and/or re-lashing the valves on an adjustable lash system. Investigation of "cold knock" is continuing. Updates will continue to be provided when available. Parts Information Check-Valve Filters Description Part Number V6, V8 (Four-Wheel Drive) FRAM PH3980 12555891 V8 (Two-Wheel Drive), Mark V8 PF1218 25160561 The FRAM PH3980 is to be used in place of the PF52. The PH3980 provides superior anti-drainback performance, a key factor in reducing cold knock. FRAM filters are to be procured locally until 08-15-95. After this date the filters may be ordered from GMSPO using the supplied part number. Orders placed to GMSPO prior to this date will not be placed on backorder. Bearings Description Part Number 0.001" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 10120992 0.001" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 10120994 0.002" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 12329758 0.002" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 12329792 Main bearing kits are currently available from GMSPO. All calibrations are currently available from GMSPO. Page 2734 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3835 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1119 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Diagrams Knock Sensor Module Page 1258 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3048 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 1459 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 2976 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2608 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3613 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1403 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1049 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1750 condition, install the appropriate main bearings as determined by the following procedure. Calibration Information - 1992-93 LB4 VIN Z The revised PROMs reduce spark advance after the engine is started. The reduction in spark lowers the cylinder pressure and eliminates the knock. The revised PROMs will NOT eliminate a piston slap (Category C) or valve train noise (Category B) concern. The base cold knock PROM contains the previously released calibration updates. For 1992 LB4, the previous field release is included for torque converter clutch (TCC) lock up (see Bulletin 137107 - Chevrolet 92-75-7A; GMC Truck 92-7A-40; Oldsmobile 92-T-34; Canada 9274L60100) for automatic transmissions, or neutral gear rattle for manual transmissions (see Bulletin 267201R - Chevrolet 92-187B-7B; GMC Truck 92-7B-149A; Canada 93-7B-105). If a vehicle has had a detonation fix PROM installed previously, select the combined detonation and cold knock fix PROM for the application. See Bulletin 376508 for more information on field fix PROM for the application and detonation. Important: Use of a detonation fix PROM in a non-detonating vehicle may result in degraded driveability. GMSPO currently stocks three (3) PROMs for each light duty 1992 model year LB4 application. Base Cold Knock Fix Combination Cold Knock and Detonation Fix GMSPO Service Parts Assistance Center (SPAC 1-800-433-6961) will have information available on each PROM part number. Select the PROM from the table. Old Broadcast Code (Old B/C Code) and Scan I.D. information has been supplied to help installed previously. Use a TECH-1 to determine the Scan I.D. of the PROM in the vehicle or remove the PROM and read the Broadcast Code (B/C Code). If the B/C Code/Scan I.D. can be found in the first table, a detonation fix has not been installed. PROMs are currently available GMSPO. 1990-95 L05 VIN K Page 3090 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Locations Engine C1 Transmission Range Switch (C1) Page 299 Page 1187 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 397 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Locations Relay Box: Locations Auxiliary Battery Wiring Page 686 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 1868 Refrigerant: Technical Service Bulletins A/C - Refrigerant Recovery/Recharge Equipment File In Section: 01 - HVAC Bulletin No.: 99-01-38-006A Date: May, 2000 WARRANTY ADMINISTRATION Subject: J-43600 ACR 2000 Essential Refrigerant Recovery/Recharge Equipment Models: 1993-2000 Passenger Cars and Light Duty Trucks with R-134a Refrigerant This bulletin is being revised to change the effective date and to update the text. Please discard Corporate Bulletin Number 99-01-38-006 (Section 01 - HVAC). Effective June 1, 2000, the use of J-43600 ACR 2000 will be required on all repairs that require A/C system recovery and are reimbursable by GM. Additionally, GM highly recommends that J-43600 ACR 2000 be used on all GM cars and trucks for customer paid A/C repairs. Important: Also effective June 1, 2000, the "Add" time for all air conditioning recovery is revised to 0.5 hours for front systems and 0.7 hours for front/rear dual systems (RPO C69 or C34). After June 1, 2000, all air conditioning claims submitted with the 0.9 hours "Add" time will be rejected for "labor hours excessive". After the completion of repairs (charging), the ACR 2000 will prompt the user to perform a snapshot of the air conditioning system operating data. The snapshot includes: ^ Maximum high side pressure. ^ Minimum low side pressure. ^ Duct outlet temperatures (2). ^ Refrigerant purity information. This information is captured on a paper printout and in a warranty code. For all GM paid repairs, the paper printout should be attached to the shop copy of the repair order. The warranty code must be submitted in the warranty claim information in the comments field. The code enables the reporting of valuable information about the repair to GM for product quality improvement. Claims submitted without this information may be subject to review and subsequent debit. The required use of J-43600 ACR 2000 raises the question of the acceptable uses for any existing recovery/recycle equipment that GM dealers are currently using. GM recognizes that many of the previously essential ACR4's are reaching the end of their useful life. There are several alternatives for existing equipment that may be considered: ^ Use the existing equipment as customer paid recovery only equipment. Example: Collision repair area. ^ Use the existing equipment as a scavenger unit for contaminated A/C systems. ^ Sell the existing units to repair facilities outside the GM dealer network. ^ Discontinue the use of the existing units if the repair/maintenance costs exceed the value of the equipment. ^ Donate the existing equipment to local technical schools. ^ Dedicate the ACR4 to A/C system flushing, using the J-42939 Flush Adapter. Page 203 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1891 Fig. 9 Cast Iron Reservoir Bleeder Adapter Installation A diaphragm type pressure bleeder must be used. It must have a rubber diaphragm between the air supply and the brake fluid to prevent air, moisture, oil, and other contaminants from entering the hydraulic system. Also, adapters are needed depending on the type of master cylinder reservoir used on the vehicle: Brake Bleeder Adapter (Plastic Reservoir) tool No. J 29567, or equivalent, Fig.8. Brake Bleeder Adapter (Cast Iron Reservoir) tool No. J 23518-01, or equivalent, Fig. 9. Page 899 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Diagram Information and Instructions Coolant Temperature Sensor/Switch (For Computer): Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 750 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 2682 Flushing Procedures using DEX-COOL(R) Important: The following procedure recommends refilling the system with DEX-COOL(R), P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M. This coolant is orange in color and has a service interval of 5 years or 240,000 km (150,000 mi). However, when used on vehicles built prior to the introduction of DEX-COOL(R), maintenance intervals will remain the same as specified in the Owner's Manual. ^ If available, use the approved cooling system flush and fill machine (available through the GM Dealer Equipment Program) following the manufacturer's operating instructions. ^ If approved cooling system flush and fill machine is not available, drain the coolant and dispose of properly following the draining procedures in the appropriate Service Manual. Refill the system using clear, drinkable water and run the vehicle until the thermostat opens. Repeat and run the vehicle three (3) times to totally remove the old coolant or until the drained coolant is almost clear. Once the system is completely flushed, refill the cooling system to a 50%-60% concentration with DEX‐COOL(R), P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M, following the refill procedures in the appropriate Service Manual. If a Service Manual is not available, fill half the capacity of the system with 100% DEX-COOL(R), P/N 12346290 (in Canada, use P/N 10953464), GM specification 6277M. Then slowly add clear, drinkable water (preferably distilled) to the system until the level of the coolant mixture has reached the base of the radiator neck. Wait two (2) minutes and reverify the coolant level. If necessary, add clean water to restore the coolant to the appropriate level. Once the system is refilled, reverify the coolant concentration using a Refractometer J 23688 (Fahrenheit scale) or J 26568 (centigrade scale) coolant tester, or equivalent. The concentration levels should be between 50% and 65%. Flushing Procedures using Conventional Silicated (Green Colored) Coolant Important: 2004-2005 Chevrolet Aveo (Pontiac Wave, Canada Only) does not use DEX‐COOL(R). The Aveo and Wave are filled with conventional, silicated engine coolant that is blue in color. Silicated coolants are typically green in color and are required to be drained, flushed and refilled every 30,000 miles (48,000 km). The Aveo and Wave are to be serviced with conventional, silicated coolant. Use P/N 12378560 (1 gal) (in Canada, use P/N 88862159 (1 L). Refer to the Owner's Manual or Service Information (SI) for further information on OEM coolant. Important: Do not mix the OEM orange colored DEX-COOL(R) coolant with green colored coolant when adding coolant to the system or when servicing the vehicle's cooling system. Mixing the orange and green colored coolants will produce a brown coolant which may be a customer dissatisfier and will not extend the service interval to that of DEX-COOL(R). Conventional silicated coolants offered by GM Service and Parts Operations are green in color. ^ If available, use the approved cooling system flush and fill machine (available through the GM Dealer Equipment Program) following the manufacturer's operating instructions. ^ If approved cooling systems flush and fill machine is not available, drain coolant and dispose of properly following the draining procedures in appropriate Service Manual. Refill the system using clear, drinkable water and run vehicle until thermostat opens. Repeat and run vehicle three (3) times to totally remove old coolant or until drained coolant is almost clear. Once the system is completely flushed, refill the cooling system to a 50%-60% concentration with a good quality ethylene glycol base engine coolant, P/N 12378560, 1 gal (in Canada, use P/N 88862159 1 L), conforming to GM specification 1825M, or recycled coolant conforming to GM specification 1825M, following the refill procedures in the appropriate Service Manual. If a Service Manual is not available, fill half the capacity of the system with 100% good quality ethylene glycol base (green colored) engine coolant, P/N 12378560 1 gal., (in Canada, use P/N 88862159 1 L) conforming to GM specification 1825M. Then slowly add clear, drinkable water (preferably distilled) to system until the level of the coolant mixture has reached the base of the radiator neck. Wait two (2) minutes and recheck coolant level. If necessary, add clean water to restore coolant to the appropriate level. Once the system is refilled, recheck the coolant concentration using a Refractometer J 23688 (Fahrenheit scale) or J 26568 (centigrade scale) coolant tester, or equivalent. Concentration levels should be between 50% and 65%. Parts Information Warranty Information Page 1405 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1007 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Specifications Compression Check: Specifications Minimum, 698 kPa (100 psi) @ 200 rpm. The lowest cylinder reading should not be less than 80% of the highest. Perform compression test with engine at normal operating temperature, spark plugs removed and throttle wide open. Page 2943 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3180 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Transfer Case Switch Four Wheel Drive Selector Switch: Locations Transfer Case Switch Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 171 Engine Control Module: Specifications With 4L80-E Automatic Transmission PCM Connector Pin-Out Page 620 15730044 Shim, Med. Beige 1 15730045 Shim, Neutral Med 1 Parts are currently available from GMSPO. Warranty Information For vehicles repaired under warranty, use: Labor Operation Description Labor Time A9780 Rt. Panel, Front Door Inner Repair 0.2 Hr A9781 Left Panel, Door Inner Repair 0.2 Hr Page 879 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 2647 For vehicles repaired under warranty, use the table. Disclaimer Page 3454 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3799 Data Link Connector: Description and Operation ALDL Connector PURPOSE The Data Link Connector (DLC) provides a means of communicating with the control module concerning engine and transmission operating parameters and accessing Diagnostic Trouble Codes (DTC). OPERATION The control module communicates a variety of information through the Serial Data Line (DLC terminal "M"). The data is transmitted at a high frequency which requires a Tech 1 diagnostic computer (scan) tool for interpretation. There are several other non-OEM scan tools available for displaying the same information. Page 3185 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1244 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 2273 condition, install the appropriate main bearings as determined by the following procedure. Calibration Information - 1992-93 LB4 VIN Z The revised PROMs reduce spark advance after the engine is started. The reduction in spark lowers the cylinder pressure and eliminates the knock. The revised PROMs will NOT eliminate a piston slap (Category C) or valve train noise (Category B) concern. The base cold knock PROM contains the previously released calibration updates. For 1992 LB4, the previous field release is included for torque converter clutch (TCC) lock up (see Bulletin 137107 - Chevrolet 92-75-7A; GMC Truck 92-7A-40; Oldsmobile 92-T-34; Canada 9274L60100) for automatic transmissions, or neutral gear rattle for manual transmissions (see Bulletin 267201R - Chevrolet 92-187B-7B; GMC Truck 92-7B-149A; Canada 93-7B-105). If a vehicle has had a detonation fix PROM installed previously, select the combined detonation and cold knock fix PROM for the application. See Bulletin 376508 for more information on field fix PROM for the application and detonation. Important: Use of a detonation fix PROM in a non-detonating vehicle may result in degraded driveability. GMSPO currently stocks three (3) PROMs for each light duty 1992 model year LB4 application. Base Cold Knock Fix Combination Cold Knock and Detonation Fix GMSPO Service Parts Assistance Center (SPAC 1-800-433-6961) will have information available on each PROM part number. Select the PROM from the table. Old Broadcast Code (Old B/C Code) and Scan I.D. information has been supplied to help installed previously. Use a TECH-1 to determine the Scan I.D. of the PROM in the vehicle or remove the PROM and read the Broadcast Code (B/C Code). If the B/C Code/Scan I.D. can be found in the first table, a detonation fix has not been installed. PROMs are currently available GMSPO. 1990-95 L05 VIN K Page 717 15730044 Shim, Med. Beige 1 15730045 Shim, Neutral Med 1 Parts are currently available from GMSPO. Warranty Information For vehicles repaired under warranty, use: Labor Operation Description Labor Time A9780 Rt. Panel, Front Door Inner Repair 0.2 Hr A9781 Left Panel, Door Inner Repair 0.2 Hr Cooling System - Coolant Recycling Information Coolant: Technical Service Bulletins Cooling System - Coolant Recycling Information Bulletin No.: 00-06-02-006D Date: August 15, 2006 INFORMATION Subject: Engine Coolant Recycling and Warranty Information Models: 2007 and Prior GM Passenger Cars and Trucks (Including Saturn) 2007 and Prior HUMMER Vehicles 2005-2007 Saab 9-7X Attention: Please address this bulletin to the Warranty Claims Administrator and the Service Manager. Supercede: This bulletin is being revised to adjust the title and Include Warranty Information. Please discard Corporate Bulletin Number 00-06-02-006C (Section 06 - Engine/Propulsion System). Coolant Reimbursement Policy General Motors supports the use of recycled engine coolant for warranty repairs/service, providing a GM approved engine coolant recycling system is used. Recycled coolant will be reimbursed at the GMSPO dealer price for new coolant plus the appropriate mark-up. When coolant replacement is required during a warranty repair, it is crucial that only the relative amount of engine coolant concentrate be charged, not the total diluted volume. In other words: if you are using two gallons of pre-diluted (50:50) recycled engine coolant to service a vehicle, you may request reimbursement for one gallon of GM Goodwrench engine coolant concentrate at the dealer price plus the appropriate warranty parts handling allowance. Licensed Approved DEX-COOL(R) Providers Important: USE OF NON-APPROVED VIRGIN OR RECYCLED DEX-COOL(R) OR DEVIATIONS IN THE FORM OF ALTERNATE CHEMICALS OR ALTERATION OF EQUIPMENT, WILL VOID THE GM ENDORSEMENT, MAY DEGRADE COOLANT SYSTEM INTEGRITY AND PLACE THE COOLING SYSTEM WARRANTY UNDER JEOPARDY. Shown in Table 1 are the only current licensed and approved providers of DEX-COOL(R). Products that are advertised as "COMPATIBLE" or "RECOMMENDED" for use with DEX-COOL(R) have not been tested or approved by General Motors. Non-approved coolants may degrade the Page 839 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2043 Some customers may use penetrating oils, grease or other lubricants on wheel studs to aid in removal or installation. Always use a suitable cleaner/solvent to remove these lubricants prior to installing the wheel and tire assemblies. Lubricants left on the wheel studs may cause improper readings of wheel nut torque. Always install wheels to clean, dry wheel studs ONLY. Notice Lubricants left on the wheel studs or vertical mounting surfaces between the wheel and the rotor or drum may cause the wheel to work itself loose after the vehicle is driven. Always install wheels to clean, dry wheel studs and surfaces ONLY. Beginning with 2011 model year vehicles, put a light coating of grease, GM P/N 1051344 (in Canada, P/N 9930370), on the inner surface of the wheel pilot hole to prevent wheel seizure to the axle or bearing hub. Wheel Stud and Lug Nut Damage Always inspect the wheel studs and lug nuts for signs of damage from crossthreading or abuse. You should never have to force wheel nuts down the stud. Lug nuts that are damaged may not retain properly, yet give the impression of fully tightening. Always inspect and replace any component suspected of damage. Tip Always start wheel nuts by hand! Be certain that all wheel nut threads have been engaged BEFORE tightening the nut. Important If the vehicle has directional tread tires, verify the directional arrow on the outboard side of the tire is pointing in the direction of forward rotation. Wheel Nut Tightening and Torque Improper wheel nut tightening can lead to brake pulsation and rotor damage. In order to avoid additional brake repairs, evenly tighten the wheel nuts to the proper torque specification as shown for each vehicle in SI. Always observe the proper wheel nut tightening sequence as shown below in order to avoid trapping the wheel on the wheel stud threads or clamping the wheel slightly off center resulting in vibration. The Most Important Service You Provide While the above information is well known, and wheel removal so common, technicians run the risk of becoming complacent on this very important Page 3003 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Locations Convenience Center Page 570 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 479 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1031 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Diagram Information and Instructions Camshaft Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 2275 Install a check valve oil filter; no other recommended actions at this time. Important: The previous actions are only applicable to short duration cold knock. These actions will not eliminate a knock occurring under load or a knock lasting for more than 10 seconds. Two main bearing procedures are recommended: 1. For main bearing replacement with the engine IN the vehicle: C, G, P, M and L vehicles 2. For main bearing replacement with the engine OUT OF the vehicle: K, S and T THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE IN THE VEHICLE Recommended for C, G, P, M and L vehicles. Important: A OEM training video has been produced for in-vehicle main bearing replacement procedure. One copy of the video will be sent to each dealer. If the video has not been received, contact XPRESS 1 Distribution Center at 1-800-783-3034. Main Bearing Clearance Determination and Installation Procedure 1. REMOVE THE SERPENTINE BELT, dipstick, dipstick tube and disconnect the negative battery cable. 2. Raise the vehicle and remove (or set aside) any parts restricting access to the oil pan bolts (i.e., starter motor, oil cooler lines, oil filter adapter, flywheel inspection cover). 3. Remove the oil pan, oil pump, and shield. 4. Remove # 5 (flange) bearing cap. Wipe the oil from the crankshaft journal and the lower main bearing insert. 5. Place a screw jack under an accessible part of the crankshaft, carefully apply pressure to the crankshaft to force it solidly against the top bearing insert. The reason for this is to remove any clearance between the top bearing insert and the crankshaft. If this step is not performed, a smaller than actual clearance will be measured. Important: This should be done as close as possible to the bearing being measured. This step is only required for on-vehicle service where the engine cannot be turned upside down as on an engine stand. 6. Place a piece of plastigage across the width of the lower bearing insert (parallel to the centerline of the crankshaft). 7. Reinstall # 5 main bearing cap. Torque to 110 N.m (80 lb ft). Do not allow crankshaft to turn. 8. Carefully remove the # 5 main bearing cap and bearing insert. The flattened plastigage will adhere to either the bearing insert or the crank journal. Do not remove the plastigage from the insert or journal. 9. On the edge of the plastigage envelope, there is a graduated scale. Without removing the flattened plastigage, measure its width at the widest point using the graduated scale on the plastigage envelope. 10. The desired main bearing clearance is 0.0008" - 0.0028". If the clearance measured with the plastigage is greater than 0.0028", write down the clearance. Next, read the back of the bearing insert to determine what size bearing was originally installed (usual STD, 0.0006", 0.0010" or 0.0012"). The size stamped on the bearing is the effective undersize when both inserts are installed. For example, a 0.0006" undersize bearing set consists of two (2) 0.0003" thicker bearing inserts, both stamped 0.0006". 11. Remove the top bearing insert using tool J 8080 and read the back to determine what size upper bearing insert was originally installed. The top insert may be different size than the bottom. 12. Calculate the original bearing undersize by dividing the size on each insert by 2, then add the values together. EXAMPLE 1: The lower insert is stamped 0.0006" and the upper is stamped 0.0010". Divide 0.0006" by two to get 0.0003". Divide 0.0010" by 2 to get 0.0005". Add 0.0003" and 0.0005" together to calculate the bearing undersize, which is 0.0008" in this case. Page 2093 Some customers may use penetrating oils, grease or other lubricants on wheel studs to aid in removal or installation. Always use a suitable cleaner/solvent to remove these lubricants prior to installing the wheel and tire assemblies. Lubricants left on the wheel studs may cause improper readings of wheel nut torque. Always install wheels to clean, dry wheel studs ONLY. Notice Lubricants left on the wheel studs or vertical mounting surfaces between the wheel and the rotor or drum may cause the wheel to work itself loose after the vehicle is driven. Always install wheels to clean, dry wheel studs and surfaces ONLY. Beginning with 2011 model year vehicles, put a light coating of grease, GM P/N 1051344 (in Canada, P/N 9930370), on the inner surface of the wheel pilot hole to prevent wheel seizure to the axle or bearing hub. Wheel Stud and Lug Nut Damage Always inspect the wheel studs and lug nuts for signs of damage from crossthreading or abuse. You should never have to force wheel nuts down the stud. Lug nuts that are damaged may not retain properly, yet give the impression of fully tightening. Always inspect and replace any component suspected of damage. Tip Always start wheel nuts by hand! Be certain that all wheel nut threads have been engaged BEFORE tightening the nut. Important If the vehicle has directional tread tires, verify the directional arrow on the outboard side of the tire is pointing in the direction of forward rotation. Wheel Nut Tightening and Torque Improper wheel nut tightening can lead to brake pulsation and rotor damage. In order to avoid additional brake repairs, evenly tighten the wheel nuts to the proper torque specification as shown for each vehicle in SI. Always observe the proper wheel nut tightening sequence as shown below in order to avoid trapping the wheel on the wheel stud threads or clamping the wheel slightly off center resulting in vibration. The Most Important Service You Provide While the above information is well known, and wheel removal so common, technicians run the risk of becoming complacent on this very important Page 310 Page 2975 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 946 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 612 1. Remove push nail from upper forward area of door panel (Figure 1). 2. Place shim on push nail stem (Figure 2). 3. Install push nail on door panel. Parts Information P/N Description Qty 15730041 Shim, Gray 1 15730042 Shim, Navy Blue 1 15730043 Shim, Ruby Red 1 Electrical Specifications Oxygen Sensor: Electrical Specifications Closed Loop .......................................................................................................................................................... 100 mV (0.1 volt) to 0.999 mV (1.0 volt) Page 3781 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1268 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3534 Idle Speed: Adjustments Minimum Idle Speed Adjustment 1. Check controlled idle speed and perform idle speed control system check first. 2. Set parking brake and block drive wheels. 3. Start engine and bring it to normal operating temperature 85°C-100°C (185°F-212°F). Turn engine "OFF." 4. Remove air cleaner, adapter and gaskets. Check that the throttle lever is not being bound by the throttle or cruise control cables. 5. With IAC valve connected, Connect Tech 1 and command IAC counts to 0. 6. With ignition "ON," engine stopped, disconnect IAC valve electrical connector. (This disables IAC valve in seated position.) Care should be taken to pull the connector straight out so that the moment of electrical disconnect is the same for all the pins. Otherwise the pintle may move as the connector is removed. 7. Start engine. With transmission in neutral, allow engine rpm to stabilize. Make sure that the ISC actuator is not contacting the throttle lever. If so refer to "IAC Actuator System Check." 8. Check rpm against specifications. Disregard IAC counts on Tech 1 scan tool with the IAC disconnected. If the engine has less than 500 miles or is checked at altitudes above 1500 feet, the idle rpm with a seated IAC valve should be lower than values above. 9. If the minimum idle speed is within specifications, no further check is required. 10. If the minimum idle speed is not within specifications, perform the following procedures: Idle Stop Screw 11. If present, remove stop screw plug by piercing it with an awl, then applying leverage. The screw is covered to discourage unauthorized adjustments. 12. With engine at normal operating temperature 85°C-100°C (185°F-212°F), adjust stop screw to obtain nominal rpm per specifications with seated IAC valve. 13. Turn ignition "OFF," and reconnect IAC valve electrical connector. 14. Disconnect Tech 1 scan tool or tachometer. 15. Use silicon sealant or equivalent to cover stop screw hole. 16. Install air cleaner and adapter. 17. Reset IAC valve. Refer to "Idle Air Control (IAC) System Check." Page 3037 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 412 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2737 Coolant Temperature Sensor/Switch (For Computer): Description and Operation Engine Coolant Temperature (ECT) Sensor PURPOSE The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40° C (-40° F) while high temperature causes low resistance (70 ohms at 130° C (266° F). OPERATION The control module supplies a 5 volt signal to the ECT sensor through a resistor in the control module and measures the voltage. The voltage will be high when the engine is cold, and low when the engine is hot. Engine coolant temperature affects most systems controlled by the control module. Page 1182 Throttle Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 2527 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3210 Fig.1-Symbols (Part 1 Of 3) Page 2710 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 945 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 2535 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 457 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1040 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Locations Engine Page 3155 1995 P TRUCK 3A-68 Change these steps on facing page: "DTC 45 Will Set When:" 1st bullet: ^ Remains above 750 mV for 61-71 seconds and in "Closed Loop." 3rd bullet: Page 1560 ^ For 1994 vehicles, splice into CKT 50 (BRN) between connector C152 and P101 (Figures 5, 6). Page 831 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 369 Diagram Information and Instructions Air Flow Meter/Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 992 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3296 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Diagram Information and Instructions Air Flow Meter/Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Specifications Throttle Position Sensor: Specifications Idle (normal) ........................................................................................................................................ ....................................................... 0.45 to 0.95 volts (maximum) ........................................................................................................................................... .......................................................... 1.25 volts Wide Open Throttle ............................................................................................................................. ........................................................... 4.0 to 4.5 volts The Throttle position Sensor is not adjustable on this engine but should read below 1.25 volts at closed throttle and about 4.5 volts at wide open throttle. Page 3603 Valve Clearance: Adjustments These models have a through bolt instead of a stud and adjusting nut. No adjustment is necessary. Page 640 Following the procedure described in Section 8A of the Service Manual, remove the Sender Assembly and replace the original Float and Arm with P/N 25312833 (see Figure 2). Reinstall the Sender Assembly and Tank. Parts Information P/N Description Qty 25312833 Float Kit, Fuel Level Sensor 1 The part is currently available from GMSPO. Warranty Information For vehicles repaired under warranty, use: Labor Operation Description Labor Time L1225 Sender Use published Assembly, Fuel Labor Operation (Tank Unit) - Time Replace Important: Labor operation is coded to base vehicle coverage in the warranty system. Warranty - OE Chrome Plated Aluminum Wheel ID Wheels: All Technical Service Bulletins Warranty - OE Chrome Plated Aluminum Wheel ID File In Section: 03 - Suspension Bulletin No.: 99-03-10-102 Date: June, 1999 INFORMATION Subject: Original Equipment Chrome Plated Aluminum Wheel Identification Models: 1999 and Prior Passenger Cars and Light Duty Trucks Chrome plated aluminum wheels have been returned to the Warranty Parts Center that are not the original equipment (OE) components. Original equipment chrome plated aluminum wheels can be identified by either a balance weight clip retention groove (1) or a step (2) that is machined around both of the wheel's rim flanges. The rim flanges (3) of painted original equipment aluminum wheels do not have a groove or a step. Chrome plated aluminum wheels that do not have the wheel rim flange groove or step are aftermarket chrome plated components and are NOT warrantable. Any aftermarket chrome wheels received by the Warranty Parts Center will be charged back to the dealership. Page 3780 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Arming Sensor Impact Sensor: Description and Operation Arming Sensor The arming sensor is a protective switch located in the power side of the deployment loop. It is calibrated to close at low level speed changes. This ensures that the inflator module is connected directly to the 36 Volt Loop Reserve (VLR) output of the DERM when either of the discriminating sensors close. Page 3373 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1498 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3878 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3402 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3827 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1494 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2992 Fig.1-Symbols (Part 1 Of 3) Page 1010 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Diagram Information and Instructions Radiator Cooling Fan Motor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Ignition System - Distributor Is Now Repairable Distributor: Technical Service Bulletins Ignition System - Distributor Is Now Repairable CHEVROLET 71-65-40 Issued: 05/01/97 SMU - SECTION 6E - REVISED ENHANCED IGNITION SYSTEM DESCRIPTION AND OPERATION SUBJECT: SERVICE MANUAL UPDATE - SECTION 6E - ENGINE CONTROLS REVISED ENHANCED IGNITION SYSTEM DESCRIPTION AND OPERATION MODELS: 1995-97 CHEVROLET AND GMC S/T, M/L, C/K, GMT600, P MODELS 1996-97 OLDSMOBILE BRAVADA WITH 4.3L, 5.0L, 5.7L, 7.4L ENGINE (VINS W, M, R, J - RPOS L35, L30, L31, L29) THIS BULLETIN IS BEING ISSUED TO INFORM TECHNICIANS OF A REVISION TO THE ENHANCED IGNITION SYSTEM DESCRIPTION AND OPERATION. THE DISTRIBUTOR IS NOW REPAIRABLE. TECHNICIANS WILL BE REFERRED TO DISTRIBUTOR OVERHAUL IN ENGINE ELECTRICAL FOR PROPER REPAIR AND REPLACEMENT OF ALL COMPONENTS. Page 3310 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Drivetrain - Slow Or No Engagement of Front Axle Technical Service Bulletin # 76-43-01A Date: 980901 Drivetrain - Slow Or No Engagement of Front Axle File In Section: 4 Drive Axle Bulletin No.: 76-43-01A Date: September, 1998 Subject: Slow or no Engagement of Front Axle when 4WD is selected (Replace Front Axle Actuator) Models: 1988-97 Chevrolet and GMC K Models excluding 1988-93 Models over 8500 # GVW This bulletin is being revised to add information to the Service Procedure, add a new part number, and include schematics. Please discard Corporate Bulletin Number 76-43-01 (Section 4 - Drive Axle). Condition Some owners may comment that the colder the outside temperature is, the longer it takes for the front axle to engage when 4 wheel drive is selected, or the front axle does not engage. Cause The front axle engagement actuator is a thermally activated component. Because of this characteristic, the time required for the actuator to complete 4 wheel drive engagement is extended as the temperature drops. Correction Replace the front axle actuator and include the applicable wiring harness kit. Refer to the Parts Information in order to determine which wiring harness kit is needed. 1996 model trucks with a build date on or after January 2, 1996 are considered as "961". If the build date of the truck is unknown, verify the 3 character "axle code" on the front axle label in order to determine which wire harness to order. This new actuator uses a motor to engage the front axle and is not affected by temperature. On 1988-93 models with a GVW rating over 8500$, the new actuator cannot be installed and the thermal actuator will remain the service part. Parts Information P/N Description Qty 26060073 Actuator Asm, Frt Drive Axle 1 22510339 Fastener 1 15313272 Harness, Jumper (Z Splice) 1 (86-93 K1-3) Parts are currently available from GMSPO. Warranty - Guidelines for Using E0420 Wheel Replace Wheels: All Technical Service Bulletins Warranty - Guidelines for Using E0420 Wheel Replace File In Section: Warranty Administration Bulletin No.: 72-05-05 Date: August, 1997 WARRANTY ADMINISTRATION Subject: Guidelines for Using EO42O Wheel Replace Models: 1989-98 Passenger Cars and Light Duty Trucks The purpose of this bulletin is to provide service personnel with guidelines for using the above subject labor operation. Effective with repair orders dated on or after September 1, 1997, dealers are to be guided by the following: ^ Aluminum Wheels (including chrome plated) with Porosity - Wheels that exhibit porosity should be repaired as described in the vehicle service manual. Wheels should not be replaced without wholesale approval. ^ Aluminum Wheels (except chrome plated) with a "Finish Defect" - Wheels that exhibit a defect in the finish, (i.e., discoloration or surface degradation) should be refinished as described in the Corporate Service Bulletin Number 53-17-03A released in May, 1996. ^ Chrome Wheels - Wheels that are chromed and found to have a finish defect can only be replaced. ^ Aluminum and chrome wheels replaced under warranty will be subject to random part review and inspection. Those wheels inspected and found not to be defective and/or should have been repaired, will be subject to charge back. Wheels damaged by normal wear, road hazards, car wash brushes, or other physical or chemical damage are not eligible for warranty coverage. Page 3432 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1011 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 1418 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3742 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3089 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 2155 Camshaft: Service and Repair Depending on vehicle and engine application, the grille, radiator and condenser, may need to be removed before removing the camshaft. 1. Remove intake manifold. 2. Remove pushrods and valve lifters. 3. Remove Front Cover, please refer to Engine, Cooling and Exhaust/Engine/Timing Components/Timing Cover/Service and Repair/ See: Timing Components/Timing Cover/Service and Repair Then the distributor. 4. Remove camshaft sprocket bolts and timing chain. 5. Remove camshaft sprocket. 6. Install two 5/16 18 x 4-5 inch bolts into camshaft bolt holes, then pull camshaft out of cylinder block. 7. Reverse procedure to install. 8. Tighten camshaft sprocket bolts to specifications. Page 3932 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table C1 Transmission Range Switch (C1) With Manual Transmission Engine Control Module: Specifications With Manual Transmission PCM Connector Pin-Out Page 3102 Knock Sensor: Service and Repair REMOVE OR DISCONNECT 1. Negative battery cable. 2. Drain cooling system. NOTE: On knock sensors which are mounted in the end of the cylinder head draining the cooling system will not be necessary. 3. Wiring harness connector from knock sensor. 4. Knock sensor from cylinder head or block. INSTALL OR CONNECT 1. Knock sensor into cylinder head or block. Apply water base caulk to sensor threads. Do not use silicon tape as this will insulate sensor from engine block. Tighten to 19 Nm (14 lb. ft.). 2. Wiring harness connector to the knock sensor. 3. Negative battery cable. 4. Refill cooling system if required. Page 3501 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 2528 Radiator Cooling Fan Motor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1200 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1826 Fluid - A/T: Technical Service Bulletins A/T - Water Or Coolant Contamination Information INFORMATION Bulletin No.: 08-07-30-035B Date: November 01, 2010 Subject: Information on Water or Ethylene Glycol in Transmission Fluid Models: 2011 and Prior GM Passenger Cars and Light Duty Trucks with Automatic Transmission Supercede: This bulletin is being revised to update model years. Please discard Corporate Bulletin Number 08-07-30-035A (Section 07 - Transmission/Transaxle). Water or ethylene glycol in automatic transmission fluid (ATF) is harmful to internal transmission components and will have a negative effect on reliability and durability of these parts. Water or ethylene glycol in ATF will also change the friction of the clutches, frequently resulting in shudder during engagement or gear changes, especially during torque converter clutch engagement. Indications of water in the ATF may include: - ATF blowing out of the transmission vent tube. - ATF may appear cloudy or, in cases of extreme contamination, have the appearance of a strawberry milkshake. - Visible water in the oil pan. - A milky white substance inside the pan area. - Spacer plate gaskets that appear to be glued to the valve body face or case. - Spacer plate gaskets that appear to be swollen or wrinkled in areas where they are not compressed. - Rust on internal transmission iron/steel components. If water in the ATF has been found and the source of the water entry has not been identified, or if a leaking in-radiator transmission oil cooler is suspected (with no evidence of cross-contamination in the coolant recovery reservoir), a simple and quick test kit is available that detects the presence of ethylene glycol in ATF. The "Gly-Tek" test kit, available from the Nelco Company, should be obtained and the ATF tested to make an accurate decision on the need for radiator replacement. This can help to prevent customer comebacks if the in-radiator transmission oil cooler is leaking and reduce repair expenses by avoiding radiator replacement if the cooler is not leaking. These test kits can be obtained from: Nelco Company Test kits can be ordered by phone or through the website listed above. Orders are shipped standard delivery time but can be shipped on a next day delivery basis for an extra charge. One test kit will complete 10 individual fluid sample tests. For vehicles repaired under warranty, the cost of the complete test kit plus shipping charges should be divided by 10 and submitted on the warranty claim as a net item. The transmission should be repaired or replaced based on the normal cost comparison procedure. Important If water or coolant is found in the transmission, the following components MUST be replaced. - Replace all of the rubber-type seals. - Replace all of the composition-faced clutch plates and/or bands. - Replace all of the nylon parts. - Replace the torque converter. - Thoroughly clean and rebuild the transmission, using new gaskets and oil filter. Important The following steps must be completed when repairing or replacing. Flush and flow check the transmission oil cooler using J 45096. Refer to Corporate Bulletin Number 02-07-30-052F- Automatic Transmission Oil Cooler Flush and Flow Test Essential Tool J 45096 TransFlow. - Thoroughly inspect the engine cooling system and hoses and clean/repair as necessary. Page 358 Wheels/Tires - Refinishing Aluminum Wheels Wheels: All Technical Service Bulletins Wheels/Tires - Refinishing Aluminum Wheels INFORMATION Bulletin No.: 99-08-51-007E Date: March 17, 2011 Subject: Refinishing Aluminum Wheels Models: 2012 and Prior GM Passenger Cars and Trucks Supercede: This bulletin is being revised to add additional model years. Please discard Corporate Bulletin Number 99-08-51-007D (Section 08 - Body and Accessories). This bulletin updates General Motor's position on refinishing aluminum wheels. GM does not endorse any repairs that involve welding, bending, straightening or re-machining. Only cosmetic refinishing of the wheel's coatings, using recommended procedures, is allowed. Evaluating Damage In evaluating damage, it is the GM Dealer's responsibility to inspect the wheel for corrosion, scrapes, gouges, etc. The Dealer must insure that such damage is not deeper than what can be sanded or polished off. The wheel must be inspected for cracks. If cracks are found, discard the wheel. Any wheels with bent rim flanges must not be repaired or refinished. Wheels that have been refinished by an outside company must be returned to the same vehicle. The Dealer must record the wheel ID stamp or the cast date on the wheel in order to assure this requirement. Refer to Refinisher's Responsibility - Outside Company later in this bulletin. Aluminum Wheel Refinishing Recommendations - Chrome-plated aluminum wheels Re-plating these wheels is not recommended. - Polished aluminum wheels These wheels have a polyester or acrylic clearcoat on them. If the clearcoat is damaged, refinishing is possible. However, the required refinishing process cannot be performed in the dealer environment. Refer to Refinisher's Responsibility - Outside Company later in this bulletin. - Painted aluminum wheels These wheels are painted using a primer, color coat, and clearcoat procedure. If the paint is damaged, refinishing is possible. As with polished wheels, all original coatings must be removed first. Media blasting is recommended. Refer to GM Aluminum Refinishing Bulletin #53-17-03A for the re-painting of this type of wheel. - Bright, machined aluminum wheels These wheels have a polyester or acrylic clearcoat on them. In some cases, the recessed "pocket" areas of the wheel may be painted. Surface refinishing is possible. The wheel must be totally stripped by media blasting or other suitable means. The wheel should be resurfaced by using a sanding process rather than a machining process. This allows the least amount of material to be removed. Important Do not use any re-machining process that removes aluminum. This could affect the dimensions and function of the wheel. Painting is an option to re-clearcoating polished and bright machined aluminum wheels. Paint will better mask any surface imperfections and is somewhat more durable than clearcoat alone. GM recommends using Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle SILVER WA9967 for a very bright look. As an option, the body color may also be used. When using any of the painting options, it is recommended that all four wheels be refinished in order to maintain color uniformity. Refer to GM Aluminum Refinishing Bulletin #53-17-03A for specific procedures and product recommendations. Refinisher's Responsibility - Outside Company Important Some outside companies are offering wheel refinishing services. Such refinished wheels will be permanently marked by the refinisher and are warranted by the refinisher. Any process that re-machines or otherwise re-manufactures the wheel should not be used. A refinisher's responsibility includes inspecting for cracks using the Zyglo system or the equivalent. Any cracked wheels must not be refinished. No welding, hammering or reforming of any kind is allowed. The wheel ID must be recorded and follow the wheel throughout the process in order to assure that the same wheel is returned. A plastic media blast may be used for clean up of the wheel. Hand and/or lathe sanding of the machined surface and the wheel window is allowed. Material removal, though, must be kept to a minimum. Re-machining of the wheel is not allowed. Paint and/or clear coat must not be present on the following surfaces: the nut chamfers, the wheel mounting surfaces and the wheel pilot hole. The refinisher must permanently ID stamp the wheel and warrant the painted/clearcoated surfaces for a minimum of one year or the remainder of the new vehicle warranty, whichever is Page 688 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1050 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1124 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3141 MAP Sensor Circuit Page 1082 HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 1256 Crankshaft Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1605 Alignment: Specifications Alignment Specifications Caster, Degrees Checking [01] ....................................................................................................................................... ............................................................. 3.0 +/- 1.0 Setting [02] ........................................................... ............................................................................................................................................. 3.0 +/1.0 Camber, Degrees Checking [01] ....................................................................................................................................... ....................................................................... 0.65 Setting [02] .......................................................... ........................................................................................................................................................ 0.65 Toe-In, Degrees Checking [03] ....................................................................................................................................... ........................................................... 0.24 +/- 0.2 Setting [03] ........................................................... ............................................................................................................................................ 0.24 +/0.2 Ball Joint Wear, inches [04] ................................................................................................................. ........................................................................... 0.08 Note: Caster angle must be corrected to level frame angle. [01] Left and right side should be equal within +1.0 deg. [02] Left and right side should equal within +0.5 deg. [03] Toe-in left and right side to be set equally per wheel and steering wheel must be held in straight ahead position within +/-5.0 deg. [04] Refer to /Steering & Suspension/ Ball Joint Inspection for inspection procedure. Page 3759 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 1097 Fig.1-Symbols (Part 1 Of 3) Page 3443 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 2191 1993 to 1995 L05 VIN K Install the appropriate check valve oil filter P/N 25160561 (PF1218 for two-wheel C-series and P/N 12555891 (FRAM PH3980) for four-wheel drive K-series). If the oil filter does not cure the condition, install the appropriate calibration from the table (calibrations are available for some 1993 and 1994 L05 applications). All calibrations are for light duty vehicles equipped with 4L60-E (M30) transmissions (no heavy duty emission/4L80-E calibrations are available). If a calibration is not offered or does not cure the short duration cold knock condition, install the appropriate main bearings as determined by the procedure. 1990-94 L19 VIN N Page 2292 EXAMPLE 2: The lower insert is stamped STD (standard) and the upper is stamped 0.0010". The undersize for a STD bearing is 0. Divide 0 by 2 to get 0. Divide 0.0010" by 2 to get 0.0005". Add 0 and 0.0005" together to calculate the bearing undersize, which is 0.0005" in this case. 13. Add the original bearing undersize calculated in step 12 to the clearance measured and written down in step 9. For example, if a clearance of 0.0030" was measured with plastigage in step 9 and the calculated bearing undersize from step 12 was 0.0005", the bearing clearance for that particular main journal is equal to 0.0030" plus 0.0005". The bearing clearance would be 0.0035" in this case. 14. Determine which of the combinations of two sizes of replacement bearings will produce the desired clearance. The two sizes available are 0.001" and 0.002". One insert of each size may be combined to produce an intermediate undersize of 0.0015". Subtract the replacement bearing size from the actual clearance to determine which bearing should be used. The bearing that should be used is the one which gives a clearance closer to 0.0008" than to 0.0028". The clearance must not be less than 0.0008". Using the example from step 11, the actual clearance is 0.0035". Subtracting 0.001" from 0.0035" will give a clearance of 0.0025", just barely within the required range. Subtracting 0.002" from 0.0035" will give a clearance of 0.0015". The 0.002" undersize bearing set would be the one to use in this case since it gives a clearance closer to 0.0008", but not less. 15. Install the replacement upper main bearing insert using tool J 8080. 16. Install the replacement lower main bearing insert in the main bearing cap. Lay a piece of plastigage across the width of the lower main bearing insert (same as step 5). 17. Repeat steps 7, 8 and 9. 18. Measuring the plastigage with the scale on the envelope, verify the clearance of the replacement bearings is within the range of 0.001" to 0.003". 19. Repeat steps 4 through 16 for each main bearing. 20. Thrust the crankshaft forward and backward several times to seat the thrust bearing. 21. Reinstall oil pump; torque to 88 N.m (65 lb ft). 22. Reinstall the oil pan and other hardware. 23. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 24. Install fuel pump fuse, start engine, check for leaks or unusual noises. 25. Road test vehicle, check for leaks or unusual noises. THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE OUT OF THE VEHICLE Recommended for K, S and T vehicles. 1. Remove the engine from the vehicle using the appropriate service manual procedure. 2. Mount the engine on an engine stand, flip the engine so the oil pan is facing up. 3. Remove the oil pan. 4. Remove the oil pump and shield. 5. Remove the dipstick tube. 6. Remove one (1) main bearing cap (must do one at a time). 7. Plasti-gage bearing. 8. If the bearing clearance is out of specification (clearance greater than 0.003 inches), remove upper main bearing from the block. 9. Check the size of the original bearing. 10. Determine what combination of new bearings are required to get the clearance in the acceptable range of 0.0008 inches to 0.0028 inches. See steps Page 863 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 1844 ^ 9.5 inch axles on vehicles built prior to mid-February 1998 are NOT compatible because RTV sealant is used on the cover pans. On vehicles built after mid-February 1998 and equipped with 9.5 inch rear axles, synthetic lubricant, P/N 12378261, can be used because the RTV was replaced with a gasket. Other mid-February changes to the 9.5 inch rear axles include a new cover pan and cover pan fasteners common to other axles. Important: The new cover pan is not retrofittable to the housing of 9.5 inch axles on vehicles built prior to mid-February 1998. A new retrofit kit is available that will enable the use of synthetic lubricant for vehicles built after mid-February, 1998. ^ All 10.5 inch axles prior to March 3, 1999 are compatible if the axle shaft hub seal (RTV) is replaced with P/N 327739 gasket when changing to synthetic lubricant. As a product improvement, this new lubricant has been released into 1999 current production C/K vehicles built after the above VIN breakpoints (Except HD3SOO models which use 75W-140 synthetic lubricant, P/N 12346140). It is recommended that synthetic lubricant be used when changing rear axle lubricant for the following reasons: ^ Potential fuel economy ^ Lower operating temperature under severe usage conditions Important: ^ You do not need to wash/rinse any non-synthetic lubricant from the axle cavity when changing over to a synthetic lubricant. However, you should remove debris from the magnet and the bottom of the axle cavity whenever the axle fluid is changed. ^ On light-duty trucks equipped with locking differentials, do NOT use a limited-slip additive. Parts Information Parts are currently available from GMSPO. Page 2614 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 3874 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 409 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 854 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3791 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 527 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 244 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 2180 Install a check valve oil filter; no other recommended actions at this time. Important: The previous actions are only applicable to short duration cold knock. These actions will not eliminate a knock occurring under load or a knock lasting for more than 10 seconds. Two main bearing procedures are recommended: 1. For main bearing replacement with the engine IN the vehicle: C, G, P, M and L vehicles 2. For main bearing replacement with the engine OUT OF the vehicle: K, S and T THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE IN THE VEHICLE Recommended for C, G, P, M and L vehicles. Important: A OEM training video has been produced for in-vehicle main bearing replacement procedure. One copy of the video will be sent to each dealer. If the video has not been received, contact XPRESS 1 Distribution Center at 1-800-783-3034. Main Bearing Clearance Determination and Installation Procedure 1. REMOVE THE SERPENTINE BELT, dipstick, dipstick tube and disconnect the negative battery cable. 2. Raise the vehicle and remove (or set aside) any parts restricting access to the oil pan bolts (i.e., starter motor, oil cooler lines, oil filter adapter, flywheel inspection cover). 3. Remove the oil pan, oil pump, and shield. 4. Remove # 5 (flange) bearing cap. Wipe the oil from the crankshaft journal and the lower main bearing insert. 5. Place a screw jack under an accessible part of the crankshaft, carefully apply pressure to the crankshaft to force it solidly against the top bearing insert. The reason for this is to remove any clearance between the top bearing insert and the crankshaft. If this step is not performed, a smaller than actual clearance will be measured. Important: This should be done as close as possible to the bearing being measured. This step is only required for on-vehicle service where the engine cannot be turned upside down as on an engine stand. 6. Place a piece of plastigage across the width of the lower bearing insert (parallel to the centerline of the crankshaft). 7. Reinstall # 5 main bearing cap. Torque to 110 N.m (80 lb ft). Do not allow crankshaft to turn. 8. Carefully remove the # 5 main bearing cap and bearing insert. The flattened plastigage will adhere to either the bearing insert or the crank journal. Do not remove the plastigage from the insert or journal. 9. On the edge of the plastigage envelope, there is a graduated scale. Without removing the flattened plastigage, measure its width at the widest point using the graduated scale on the plastigage envelope. 10. The desired main bearing clearance is 0.0008" - 0.0028". If the clearance measured with the plastigage is greater than 0.0028", write down the clearance. Next, read the back of the bearing insert to determine what size bearing was originally installed (usual STD, 0.0006", 0.0010" or 0.0012"). The size stamped on the bearing is the effective undersize when both inserts are installed. For example, a 0.0006" undersize bearing set consists of two (2) 0.0003" thicker bearing inserts, both stamped 0.0006". 11. Remove the top bearing insert using tool J 8080 and read the back to determine what size upper bearing insert was originally installed. The top insert may be different size than the bottom. 12. Calculate the original bearing undersize by dividing the size on each insert by 2, then add the values together. EXAMPLE 1: The lower insert is stamped 0.0006" and the upper is stamped 0.0010". Divide 0.0006" by two to get 0.0003". Divide 0.0010" by 2 to get 0.0005". Add 0.0003" and 0.0005" together to calculate the bearing undersize, which is 0.0008" in this case. Page 562 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 487 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 445 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 2978 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 2559 Radiator Cooling Fan Motor: Component Tests and General Diagnostics When the Ignition Switch is on the RUN, BULB TEST or START positions, voltage is applied to the coil (power side) of the Auxiliary Cooling Fan Relay through the IGN E Fuse. Ground is supplied to the coil (ground side) of the Auxiliary Cooling Fan Relay through either the Auxiliary Cooling Fan Temperature Switch, High Pressure Switch or the A/C Controller. When either of the above three components provide ground to the coil of the Auxiliary Cooling Fan Relay, it energizes and the contacts close. Voltage is applied through the AUX FAN Fuse and the closed contacts of the Auxiliary Cooling Fan Relay to the Auxiliary Cooling Fan Motor. Since the Auxiliary Cooling Fan Motor is grounded at G112, it runs. Harness View Engine Page 2933 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1206 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 533 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 825 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 2997 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 1148 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Diagram Information and Instructions Camshaft Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 2183 Warranty Information Page 1111 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 1827 Disclaimer Page 3783 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3135 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1696 2. Remove the serpentine belt from the accessory drive system. 3. Install the tool onto the power steering pulley. Position the legs of the tool into the outer grooves of the pulley, farthest from the front of the engine. 4. Install the retaining cord around the pulley and to the legs of the tool. 5. Put on the laser safety glasses provided with the tool. 6. Depress the switch on the rear of the tool to activate the light beam. 7. Rotate the power steering pulley as required to project the light beam onto the crankshaft balancer pulley grooves. 8. Inspect for proper power steering pulley alignment. - If the laser beam projects onto the second rib or raised area (1), the pulleys are aligned properly. - If the laser beam projects more than one-quarter rib 0.9 mm (0.035 in) mis-alignment, adjust the position of the power steering pulley as required. - Refer to SI for Power Steering Pulley Removal and Installation procedures. 9. Install the serpentine belt to the accessory drive system in the original orientation. 10. Operate the vehicle and verify that the belt noise concern is no longer present. Tool Information Please visit the GM service tool website for pricing information or to place your order for this tool. Page 389 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 70 Cruise Control Module: Locations CRUISE CONTROL MODULE L/H Rear Side Of Engine Compartment Left Hand Rear Side Of Engine Compartment Diagrams Engine Coolant Level Indicator Module Page 3304 Vehicle Speed Sensor: Description and Operation Vehicle Speed Sensor (Manual Transmission) Vehicle Speed Sensor (2WD) Vehicle Speed Sensor (4WD) PURPOSE: The Vehicle Speed Sensor (VSS) is made up of a coil mounted on the transmission and a tooth rotor mounted to the output shaft in the transmission. As each rotor tooth nears the coil, the coil produces an AC voltage pulse. As the vehicle speed increases the number of AC voltage pulses per second increases. The vehicle speed signal buffer processes inputs from the VSS and output signal to the speedometer, control module, and cruise control module. The VSS buffer signal takes the voltage pulses from the VSS and uses them to open and close four solid state output switches to ground at a rate proportional to vehicle speed. The VSS buffer is matched to the vehicle based on final drive ratio and tire size. It is important to ensure that the correct VSS buffer is installed in the vehicle if replacement is necessary. Page 3626 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 2135 Disclaimer Page 2081 Do not use cleaning solutions that contain hydrofluoric, oxalic and most other acids on chrome wheels (or any wheels). If the customer is unsure of the chemical make-up of a particular wheel cleaner, it should be avoided. For wheels showing signs of milky staining from acidic cleaners, refer to Customer Assistance and Instructions below. Warranty of Stained Chrome Wheels Stained wheels are not warrantable. Most acid based cleaners will permanently stain chrome wheels. Follow-up with dealers has confirmed that such cleaners were used on wheels that were returned to the Warranty Parts Center (WPC). Any stained wheels received by the WPC will be charged back to the dealership. To assist the customer, refer to Customer Assistance and Instructions below. Pitting or Spotted Appearance of Chrome Wheels Figure 2 A second type or staining or finish disturbance may result from road chemicals, such as calcium chloride used for dust control of unpaved roads. The staining will look like small pitting (refer to Figure 2). This staining will usually be on the leading edges of each wheel spoke, but may be uniformly distributed. If a vehicle must be operated under such conditions, the chrome wheels should be washed with mild soap and water and thoroughly rinsed as soon as conveniently possible. Important Road chemicals, such as calcium chloride used for dust control of unpaved roads, can also stain chrome wheels. The staining will look like small pitting. This staining will usually be on the leading edges of each wheel spoke. This is explained by the vehicle traveling in the forward direction while being splashed by the road chemical. If a vehicle must be operated under such conditions, the chrome wheels should be washed with mild soap and water and thoroughly rinsed as soon as conveniently possible. Warranty of Pitted or Spotted Chrome Wheels Wheels returned with pitting or spotting as a result of road chemicals may be replaced one time. Damage resulting from contact with these applied road chemicals is corrosive to the wheels finish and may cause damage if the wheels are not kept clean. Important Notify the customer that this is a one time replacement. Please stress to the customer the vital importance of keeping the wheels clean if they are operating the vehicle in an area that applies calcium chloride or other dust controlling chemicals! "GM of Canada" dealers require prior approval by the District Manager - Customer Care and Service Process (DM-CCSP). "Stardust" Corrosion of Chrome Wheels Figure 3 A third type of finish disturbance results from prolonged exposure to brake dust and resultant penetration of brake dust through the chrome. As brakes are applied hot particles of brake material are thrown off and tend to be forced through the leading edge of the wheel spoke windows by airflow. These Page 1460 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Controlled Idle Speed Idle Speed: Adjustments Controlled Idle Speed Before performing this check, there should be no DTC(s) displayed, idle air control system has been checked and ignition timing correct. 1. Set parking brake and block drive wheels. 2. Connect a Tech 1 scan tool to the DLC connector with tool in open mode. 3. Start engine and bring it to normal operating temperature. 4. Check for correct state of PRNDL position (R-D-L) switch on Tech 1 scan tool. 5. Check specifications for controlled idle speed and IAC valve pintle position (counts). 6. If within specifications, the idle speed is being correctly controlled by the control module. 7. If not within specifications, refer to Rough, Unstable or Incorrect Idle, Stalling. See: Powertrain Management/Fuel Delivery and Air Induction/Testing and Inspection Page 2602 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 1967 1. Center the repair unit over the injury as a reference and outline an area larger than the unit so that buffing will not remove the crayon marks. 2. Remove the repair unit. 3. DO NOT overlap previous or multiple repair units. 4. Consult your repair material supplier for proper repair unit selection. Buffing 1. To prevent contamination and preserve the outline, buff within the marked area thoroughly and evenly with a low speed buffing tool using a fine wire brush or gritted rasp. 2. Buff to a smooth velvet surface (RMA #1 or #2 buffed texture). 3. Use caution not to gouge the inner liner or expose casing fabric. 4. Remove any buffing dust with a vacuum cleaner. 5. Consult your repair material supplier for a proper buffing tool. Cementing Apply chemical cement according to the repair material manufacturer's procedures. Repair Unit Application Shift Indicator Light Application and Operation Air Flow Meter/Sensor Relay: Technical Service Bulletins Shift Indicator Light Application and Operation File In Section: 7 - Transmission Bulletin No.: 36-72-07A Date: February, 1995 Subject: Manual Transmission Shift Indicator Light Application and Operation Models: 1993-95 Chevrolet and GMC Truck C/K and S/T Models with Manual Transmission This bulletin is being revised to add the 1995 model year. Please discard bulletin number 367207 (Group Reference - Transmission). Certain trucks are not equipped with a shift indicator light. The shift light is commonly used to achieve improved fuel economy by prompting the driver when to upshift. Depending on the engine/transmission installed in the vehicle, the shift light can have the following characteristics: ^ Indicates proper shift point for maximum fuel economy. ^ Indicates engine over-speed. ^ Shift light is inoperative. The following charts detail normal shift light operation: 1993 Models: Page 415 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 2530 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Recall - Tire Bead Damage During Mounting Technical Service Bulletin # 96-C-36 Date: 960601 Recall - Tire Bead Damage During Mounting 96-C-36 CAMPAIGN: TIRE BEAD DAMAGE....... Issued: 06/01/96 PRODUCT SAFETY CAMPAIGN SUBJECT: 96-C-36 - TIRE BEAD DAMAGE DURING MOUNTING (GENERAL TIRES ONLY) MODELS: 1995-1996 C/K CREW CAB AND G VAN 30 SERIES WITH RPO XHP/YHP-FLINT ASSEMBLY ONLY (VIN CODE "F") The Highway Safety Act, as amended, provides that each vehicle which is subject to a recall campaign of this type must be adequately repaired within a reasonable time after the customer has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is prima facie evidence of failure to repair within a reasonable time. If the condition is not adequately repaired within a reasonable time, the customer may be entitled to an identical or reasonably equivalent vehicle at no charge or to a refund of the purchase price less a reasonable allowance for depreciation. To avoid having to provide these burdensome remedies, every effort must be made to promptly schedule an appointment with each customer and to repair their vehicle as soon as possible. As you will see in reading the copy of the divisional letter that is being sent to customers, the customers are being instructed to contact the appropriate Customer Assistance Center if their dealer does not remedy the condition within five (5) days of the mutually agreed upon service date. If the condition is not remedied within a reasonable time, they are instructed on how to contact the National Highway Traffic Safety Administration. Defect/Vehicles Involved General Motors has decided that a defect which relates to motor vehicle safety exists in certain 1995-1996 G Vans 30 Series and C/K Crew Cab trucks equipped with General Ameri*550 AS LT225/75R16D tires. Some of these vehicles have bead damage to the tires which occurred during tire mounting. This damage to the tire reinforcing structure in the bead "toe" area would likely manifest itself as a bulge in the sidewall after the tire is inflated. The bulge may be noticeable when the tire is used in a single wheel position. But, if it is used in a dual rear wheel installation, the bulges on the tires would face each other and would not be noticeable. Typically, this condition would result in a slow air loss causing the tire to go flat. However, it is possible for the damage to result in a rapid air loss, which could cause injuries to anyone if they were handling the tire when this occurred. To correct this condition, dealers are to demount each General tire and inspect it for bead damage. If bead damage is present, the tire will be replaced. Involved are CERTAIN 1995-1996 G Vans 30 Series and C/K Crew Cab trucks equipped with General Ameri*550 AS LT225/75R16D tires, and built within the VIN breakpoints as shown. NOTICE: Dealers should confirm vehicle eligibility through VISS (Vehicle Information Service System) or Service Net (GMC only) prior to beginning campaign repairs. [Not all vehicles within the above breakpoints may be involved] Involved vehicles have been identified by Vehicle Identification Number. Computer listings containing the complete Vehicle Identification Number, customer name and address data have been prepared, and are being furnished to involved dealers with the campaign bulletin. The Customer name and Valve Clearance Specifications Valve Clearance: Specifications Valve Clearance Specifications Engine Liter/CID .................................................................................................................................. ........................................................... 7.4L/V8-454 All specifications given in inches. Stem Diameter Std. Intake ................................................................................................................................................... ...................................................... 0.3715-0.3722 Exhaust ................................................................ ...................................................................................................................................... 0.3715-0.3722 Maximum Tip Refinish ......................................................................................................................... ........................................................................ [03] Face Angle .......................................................... ....................................................................................................................................................... 45 deg. Margin [01] Intake ................................................................................................................................................... .................................................................. 0.0315 Exhaust ................................................................. .................................................................................................................................................. 0.0315 Valve Lash ........................................................................................................................................... ........................................................................... [06] [01] Minimum. [03] Grind only enough to provide true surface. After grinding valve stems, ensure sufficient clearance remains between rocker arm & valve spring cap or rotator. [06] Torque rocker arm bolt to 40 ft. lbs Page 89 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 2935 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1604 Use the same procedure used in determining the "Z" height. "D" height should be 7.17 inches. Page 3356 Fig.1-Symbols (Part 1 Of 3) Page 2792 Exhaust Manifold: Service and Repair 1. Disconnect battery ground cable, then raise and support vehicle. 2. Disconnect exhaust pipe from manifold. 3. Lower vehicle. 4. Disconnect oxygen sensor electrical connector from left side manifold. Do not remove oxygen sensor from the manifold unless it is to be replaced. Remove dipstick tube bracket from right side manifold. 5. Remove power steering pump bracket from left side manifold. 6. Remove heat stove pipe from right side manifold. 7. Disconnect AIR hose from check valve. 8. Remove manifold attaching bolts, washers, heat shield and tab washers. 9. Remove exhaust manifold. 10. Reverse procedure to install, using a new gasket. Page 1674 Distributor: Service and Repair Distributor Replacement Preassembled replacement distributors are not available. Components are available to assemble a new distributor. Some components, such as the air cleaner, may need to be removed to reach the distributor. The distributor has a separate ignition coil that mounts to a bracket on the top of the engine. REMOVE OR DISCONNECT Make sure the ignition switch is "OFF." 1. Air cleaner and hoses. 2. Electrical connectors at the side of the distributor cap. 3. Two screws on the sides of the distributor cap. 4. Ignition coil wire and spark plug wires on either the left or right side of the distributor. 5. Distributor cap and move it aside. A. Use chalk to note the position of the rotor in relation to the engine. B. Use chalk to note the position of the distributor housing in relation to the engine. 6. Distributor bolt and hold-down clamp. 7. Distributor. INSTALL OR CONNECT 1. Distributor. A. To ensure correct timing of the distributor, it must be installed with the rotor correctly positioned as noted in step 5 of the removal procedure. Line up the rotor to the mark on the engine, and the mark on the housing to the engine. B. If the distributor shaft won't drop into the engine, remove the distributor, insert a screwdriver into the hole for the distributor and rotate the oil pump driveshaft so it lines up with the distributor drive gear. 2. Hold-down clamp and bolt. Tighten Bolt to 27 Nm (20 lbs. in.). 3. Distributor cap with two screws. 4. Wiring harness connectors to the sealed ICM connectors at the side of the distributor. 5. Spark plug wires and coil wire. 6. Air cleaner and hoses. Check the ignition base timing. Page 690 Brake Light / TCC Switch Jumper Harness Connector Page 95 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Service and Repair Timing Cover: Service and Repair 1. Remove vibration damper and water pump. 2. Remove oil pan, then the front cover retaining screws and cover, please refer to Engine, Cooling and Exhaust/Engine/Engine Lubrication/Oil Pan, Engine/Service and Repair/ See: Engine Lubrication/Oil Pan/Service and Repair 3. Clean gasket surface of block and timing case cover. 4. Remove any excess oil pan gasket material that may be protruding at the oil pan to engine block junction. 5. Apply a thin bead of RTV sealer part No. 0.052366, or equivalent, to joint formed at oil pan and block. 6. Coat new gasket with sealer and position it on cover, then install cover to oil pan seal on cover and coat bottom of seal with engine oil. 7. Position cover on engine and install cover mounting flange reinforcement (if equipped). 8. Install cover screws and tighten to specifications, alternately and evenly while pressing downward on cover so that dowels are aligned with holes in cover. Do not force cover over dowels as cover can be distorted. 8. Install remaining cover screws, vibration damper and water pump. Page 312 Page 895 Knock Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1509 Fluid Pressure Sensor/Switch: Testing and Inspection 4L80-E (MT1) Transmission Transmission Range (TR) Pressure Switch Assembly Circuit Check Page 1584 Power Window Switch: Diagrams Power Window and Door Lock Switch, LH Harness Connector Faces Harness View Engine Page 668 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3444 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 2969 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1907 I/P Fuse Block Page 937 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1104 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 46 Electronic Brake Control Module: Service and Repair Fig. 224 EHCU/BPMV Mounting. (EHCU) Electro-Hydraulic Control Unit / (BPMV) Brake Pressure Modulator Valve Module is not serviceable and must be replaced as a unit. 1. Disconnect electrical connectors from EHCU/BPMV module. 2. Disconnect brake pipes from module. 3. Remove module and bracket assembly mounting bolts, then the module and bracket assembly from the vehicle. 4. Remove bolts attaching module to bracket assembly, Fig. 224. 5. Reverse procedure to install, noting the following: a. Torque module to bracket bolts to 5 ft. lbs. b. Torque bracket attaching bolts to 33 ft. lbs. c. Torque brake line fittings to module 16 ft. lbs. d. Bleed brake system and EHCU/BPMV module. See: Brakes and Traction Control/Brake Bleeding Page 767 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 3737 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 2307 Remove the drive axle (halfshaft) completely from the vehicle to gain access to the output shaft. DO NOT try to remove the output shaft without first removing the drive axle (halfshaft) from the vehicle. Damage to halfshaft boots (seals) may result. Furthermore, attempts to reinstall the output shaft into the differential with the halfshaft pushed off to one side may result In damage to the output shaft seal. ^ Avoid contact between the inboard and outboard halfshaft boots (seals) and any surface which could cause a cut, nick, or abrasion. ^ When loosening or tightening the 6 bolts which secure the halfshaft to the output shaft, care should be taken to prevent tools from contacting the inboard halfshaft boot (seal). Page 2851 Pinout Description: C1 (Part 2 Of 2) Engine Controls - TBI, C2 Page 254 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2272 1992 LB4 VIN Z with "cold knock" only 1992-93 LB4 VIN Z with "cold knock" and installed field fix PROM OR with "cold knock" and detonation 1990-95 LB4 VIN Z Install check valve oil filter P/N 12555891 (FRAM PH3980). If the filter does not cure the condition, install the appropriate calibration from the tables (calibrations are available for all 1992 and some 1993 LB4 applications). If a calibration is not offered or does not cure the short duration cold knock Horn Contact Replacement (Plunger Switch) Horn Switch: Service and Repair Horn Contact Replacement (Plunger Switch) REMOVAL Remove or disconnect the following: 1. Negative battery cable. 2. Disable the SIR system. See: Body and Frame/Interior Moulding / Trim/Dash Board / Instrument Panel/Air Bag(s) Arming and Disarming/Service and Repair 3. Inflator module. See: Restraint Systems/Air Bag Systems/Air Bag/Service and Repair 4. Horn contact from steering column. See: INSTALLATION CAUTION: Always use the correct fastener in the proper location. When you replace a fastener, use ONLY the exact part number for that application. The manufacturer will call out those fasteners that require a replacement after removal. The manufacturer will also call out the fasteners that require thread lockers or thread sealant. UNLESS OTHERWISE SPECIFIED, do not use supplemental coatings (paints, greases, or other corrosion Inhibitors) on threaded fasteners or fastener joint interfaces. Generally, such coatings adversely affect the fastener torque and joint clamping force, and may damage the fastener. When you install fasteners, use the correct tightening sequence and specifications. Following these instructions can help you avoid damage to parts and systems. Install or connect the following: 1. Horn contact into steering column. See: 2. Inflator module to the steering wheel. See: Restraint Systems/Air Bag Systems/Air Bag/Service and Repair 3. Negative battery cable. 4. Enable the SIR system. See: Body and Frame/Interior Moulding / Trim/Dash Board / Instrument Panel/Air Bag(s) Arming and Disarming/Service and Repair Instruments - Excessive Fuel Gauge Fluctuation Fuel Gauge Sender: Customer Interest Instruments - Excessive Fuel Gauge Fluctuation File In Section: 8 - Chassis/Body Electrical Bulletin No.: 76-83-05 Date: September, 1997 Subject: Excessive Fuel Gauge Fluctuation (Install Fuel Level Damper Kit) Models: 1995-97 Chevrolet and GMC C/K 4 Door Utility Models Condition Some owners may comment about excessive fuel gauge needle fluctuation when making turns or braking with less than a half tank of fuel. Correction Install fuel level damper module kit P/N 12167652 following the procedure described on the instruction sheets included with the kit. Parts Information P/N Description Qty 12167652 Module Kit, Fuel Level Damper 1 Parts are currently available from GMSPO. Warranty Information For vehicles repaired under warranty, use: Labor Op Description Labor Time N4844 Module, Anti-slosh - Install 0.8 hr Important: Labor operation is coded to base vehicle coverage in the warranty system. Page 3632 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 780 Camshaft Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Diagram Information and Instructions Neutral Safety Switch: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 2871 Fig.2-Symbols (Part 2 Of 3) Restraints - Passenger Presence System Information Seat Occupant Sensor: Technical Service Bulletins Restraints - Passenger Presence System Information INFORMATION Bulletin No.: 06-08-50-009F Date: December 23, 2010 Subject: Information on Passenger Presence Sensing System (PPS or PSS) Concerns With Custom Upholstery, Accessory Seat Heaters or Other Comfort Enhancing Devices Models: 2011 and Prior GM Passenger Cars and Trucks Equipped with Passenger Presence Sensing System Supercede: This bulletin is being revised to update the model years. Please discard Corporate Bulletin Number 06-08-50-009E (Section 08 - Body and Accessories). Concerns About Safety and Alterations to the Front Passenger Seat Important ON A GM VEHICLE EQUIPPED WITH A PASSENGER SENSING SYSTEM, USE THE SEAT COVERS AND OTHER SEAT-RELATED EQUIPMENT AS RELEASED BY GM FOR THAT VEHICLE. DO NOT ALTER THE SEAT COVERS OR SEAT-RELATED EQUIPMENT. ANY ALTERATIONS TO SEAT COVERS OR GM ACCESSORIES DEFEATS THE INTENDED DESIGN OF THE SYSTEM. GM WILL NOT BE LIABLE FOR ANY PROBLEMS CAUSED BY USE OF SUCH IMPROPER SEAT ALTERATIONS, INCLUDING ANY WARRANTY REPAIRS INCURRED. The front passenger seat in many GM vehicles is equipped with a passenger sensing system that will turn off the right front passenger's frontal airbag under certain conditions, such as when an infant or child seat is present. In some vehicles, the passenger sensing system will also turn off the right front passenger's seat mounted side impact airbag. For the system to function properly, sensors are used in the seat to detect the presence of a properly-seated occupant. The passenger sensing system may not operate properly if the original seat trim is replaced (1) by non-GM covers, upholstery or trim, or (2) by GM covers, upholstery or trim designed for a different vehicle or (3) by GM covers, upholstery or trim that has been altered by a trim shop, or (4) if any object, such as an aftermarket seat heater or a comfort enhancing pad or device is installed under the seat fabric or between the occupant and the seat fabric. Aftermarket Seat Heaters, Custom Upholstery, and Comfort Enhancing Pads or Devices Important ON A GM VEHICLE EQUIPPED WITH A PASSENGER SENSING SYSTEM, USE ONLY SEAT COVERS AND OTHER SEAT-RELATED EQUIPMENT RELEASED AS GM ACCESSORIES FOR THAT VEHICLE. DO NOT USE ANY OTHER TYPE OF SEAT COVERS OR SEAT-RELATED EQUIPMENT, OR GM ACCESSORIES RELEASED FOR OTHER VEHICLE APPLICATIONS. GM WILL NOT BE LIABLE FOR ANY PROBLEMS CAUSED BY USE OF SUCH IMPROPER SEAT ACCESSORIES, INCLUDING ANY WARRANTY REPAIRS MADE NECESSARY BY SUCH USE. Many types of aftermarket accessories are available to customers, upfitting shops, and dealers. Some of these devices sit on top of, or are Velcro(R) strapped to the seat while others such as seat heaters are installed under the seat fabric. Additionally, seat covers made of leather or other materials may have different padding thickness installed that could prevent the Passenger Sensing System from functioning properly. Never alter the vehicle seats. Never add pads or other devices to the seat cushion, as this may interfere with the operation of the Passenger Sensing System and either prevent proper deployment of the passenger airbag or prevent proper suppression of the passenger air bag. Disclaimer Page 2842 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3375 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 152 Underhood Fuse - Relay Center Wheels - Plastic Wheel Nut Covers Loose/Missing Wheel Fastener: Customer Interest Wheels - Plastic Wheel Nut Covers Loose/Missing Bulletin No.: 01-03-10-009A Date: July 27, 2004 TECHNICAL Subject: Plastic Wheel Nut Covers Missing and/or Loose (Replace Missing Covers and Add Sealant to All Covers) Models: 2005 and All Prior Passenger Cars (Except All Cadillac Models and Pontiac GTO) with Plastic Wheel Nut Covers Supercede: This bulletin is being revised to add additional models years. Please discard Corporate Bulletin Number 01-03-10-009. Condition Some customers may comment that the plastic wheel nut covers are missing and/or loose. Correction Important: ^ DO NOT USE a silicone-based adhesive. ^ Do not apply the *permatex(R) around the threads in a circular pattern. ^ Apply a single bead across the threads approximately 10 mm (0.4 in) in length, 5 mm (0.2 in) in height and 5 mm (0.2 in) in width. Replace any missing plastic wheel nut covers with the appropriate covers and apply Permatex(R) # 2 Form A Gasket Sealant(R) to the threads of all the plastic wheel nut covers. Tighten finger tight plus a 1/4 turn with a hand wrench. *We believe this source and their products to be reliable. There may be additional manufacturers of such material. General Motors does not endorse, indicate any preference for or assume any responsibility for the products from this firm or for any other such items which may be available from other sources. Permatex(R) # 2 Form A Gasket Sealant(R) part numbers (available at your local parts supplier) ^ P/N 80009 (2A/2AR) - 44 ml (1.5 oz) tube boxed ^ P/N 80015 (2AR) - 44 ml (1.5 oz) tube carded ^ P/N 80010 (2B/2BR) - 89 ml (3 oz) tube boxed ^ P/N 80016 (2BR) - 89 ml (3 oz) tube carded ^ P/N 80011 (2C) - 325 ml (11 oz) tube boxed Warranty Information For vehicles repaired under warranty, use the table. Electric Brake Release Switch Brake Switch (Cruise Control): Description and Operation Electric Brake Release Switch The brake pedal is equipped with two switches: a combination stop light/cruise control/TCC switch and a plunger type release switch. Each switch disengages the cruise control system when the brake pedal is depressed. When the brake pedal is released, the system will remain disengaged. Page 833 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3093 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3836 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1849 Fluid - Differential: Fluid Type Specifications Front Axle SAE 80W-90 GL5 Gear Lubricant. GM P/N 1052271 Locking Differential (G80) This Article has been updated by TSB # 76-02-02A. SAE 80W-90 GL5 Gear Lubricant, GM P/N 1052271. Do not use limited slip additive. Non-Locking Differential Rear Axle with Non Limited Slip or Non Locking Differentials HD-3500 Trucks (Dana 11.0 axles) Recommended Lubricant - GM P/N 12346140, SAE 75W-140 Synthetic Gear Lubricant. 1999 GMT 800 Trucks Recommended Lubricant - GM P/N 12378261, SAE 75W-90 Synthetic Axle Lubricant. All other non limited-slip or non locking differentials including B and D cars, S/T, M/L, G, P, and C/K trucks except GMT 800 trucks, and as noted above. Recommended Lubricant - GM P/N 1052271 or an SAE 80W90 GL-5 Gear Lubricant. Page 3043 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3033 Crankshaft Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 672 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3346 Oil Pressure Switch (For Fuel Pump): Service and Repair Oil Pressure Switch REMOVE OR DISCONNECT 1. Electrical connector. 2. Oil pressure switch using wrench J 35748. INSTALL OR CONNECT 1. Oil pressure switch. 2. Electrical connector. Instruments - Fuel Gauge Indicates Empty When Not Fuel Gauge Sender: Customer Interest Instruments - Fuel Gauge Indicates Empty When Not File In Section: 8 - Chassis/Body Electrical Bulletin No.: 76-83-03A Date: June, 1998 Subject: Fuel Gauge Indicates Empty with 7-8 Gallons (30 Liters) Left in Tank (Replace Fuel Level Sensor Float Arm Assembly) Models: 1995-97 Chevrolet and GMC C/K 4 Door Models Built Prior to VIN Breakpoints: Models VIN Breakpoints Chevrolet VJ355982 GMC VJ724930 This bulletin is being revised to change the labor operation number. Please discard Corporate Bulletin Number 76-83-03 (Section 8 - Chassis/Body Electrical). Condition Some owners may comment that the fuel gauge indicates empty after only going 200 to 250 miles, and they are only able to put approximately 23 gallons or less of fuel in the 30 gallon tank. Cause The Fuel Level Indication System was designed with excessive empty reserve. The Fuel Level Sender will be labeled with Broadcast code "TCB", (see Figure 1). Vehicles built after December 14, 1996, have the revised Float Arm Assembly. Correction Page 864 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3117 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 1406 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Service and Repair Fuel Pressure Release: Service and Repair PROCEDURE: NOTE: A constant bleed feature in the pressure regulator relieves pressure when engine is turned "OFF." - Disconnect negative battery terminal to avoid possible fuel discharge if an accidental attempt is made to start the engine. - Loosen fuel filler cap to relieve tank vapor pressure. - The internal constant bleed feature of the TBI relieves fuel pump system pressure when the engine is turned "OFF." Therefore, NO further pressure relief procedure is required. Page 3263 5-Speed Manual Transmission W/4WD HD Electronic 4-Speed Automatic Overdrive Transmission Page 1752 Install a check valve oil filter; no other recommended actions at this time. Important: The previous actions are only applicable to short duration cold knock. These actions will not eliminate a knock occurring under load or a knock lasting for more than 10 seconds. Two main bearing procedures are recommended: 1. For main bearing replacement with the engine IN the vehicle: C, G, P, M and L vehicles 2. For main bearing replacement with the engine OUT OF the vehicle: K, S and T THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE IN THE VEHICLE Recommended for C, G, P, M and L vehicles. Important: A OEM training video has been produced for in-vehicle main bearing replacement procedure. One copy of the video will be sent to each dealer. If the video has not been received, contact XPRESS 1 Distribution Center at 1-800-783-3034. Main Bearing Clearance Determination and Installation Procedure 1. REMOVE THE SERPENTINE BELT, dipstick, dipstick tube and disconnect the negative battery cable. 2. Raise the vehicle and remove (or set aside) any parts restricting access to the oil pan bolts (i.e., starter motor, oil cooler lines, oil filter adapter, flywheel inspection cover). 3. Remove the oil pan, oil pump, and shield. 4. Remove # 5 (flange) bearing cap. Wipe the oil from the crankshaft journal and the lower main bearing insert. 5. Place a screw jack under an accessible part of the crankshaft, carefully apply pressure to the crankshaft to force it solidly against the top bearing insert. The reason for this is to remove any clearance between the top bearing insert and the crankshaft. If this step is not performed, a smaller than actual clearance will be measured. Important: This should be done as close as possible to the bearing being measured. This step is only required for on-vehicle service where the engine cannot be turned upside down as on an engine stand. 6. Place a piece of plastigage across the width of the lower bearing insert (parallel to the centerline of the crankshaft). 7. Reinstall # 5 main bearing cap. Torque to 110 N.m (80 lb ft). Do not allow crankshaft to turn. 8. Carefully remove the # 5 main bearing cap and bearing insert. The flattened plastigage will adhere to either the bearing insert or the crank journal. Do not remove the plastigage from the insert or journal. 9. On the edge of the plastigage envelope, there is a graduated scale. Without removing the flattened plastigage, measure its width at the widest point using the graduated scale on the plastigage envelope. 10. The desired main bearing clearance is 0.0008" - 0.0028". If the clearance measured with the plastigage is greater than 0.0028", write down the clearance. Next, read the back of the bearing insert to determine what size bearing was originally installed (usual STD, 0.0006", 0.0010" or 0.0012"). The size stamped on the bearing is the effective undersize when both inserts are installed. For example, a 0.0006" undersize bearing set consists of two (2) 0.0003" thicker bearing inserts, both stamped 0.0006". 11. Remove the top bearing insert using tool J 8080 and read the back to determine what size upper bearing insert was originally installed. The top insert may be different size than the bottom. 12. Calculate the original bearing undersize by dividing the size on each insert by 2, then add the values together. EXAMPLE 1: The lower insert is stamped 0.0006" and the upper is stamped 0.0010". Divide 0.0006" by two to get 0.0003". Divide 0.0010" by 2 to get 0.0005". Add 0.0003" and 0.0005" together to calculate the bearing undersize, which is 0.0008" in this case. Page 3145 Manifold Absolute Pressure (MAP) Sensor: Service and Repair MAP Sensor REMOVE OR DISCONNECT: 1. Negative battery cable. 2. EVAP Vacuum harness assembly. 3. Electrical connector releasing locking tab. 4. Bolts or release lock tabs and remove sensor. INSTALL OR CONNECT: 1. Bolts or snap sensor on bracket. 2. Electrical connector. 3. EVAP Vacuum harness. 4. Negative battery cable. Page 433 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1393 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3844 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3756 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 390 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 2113 Important: 3. Mask off all wheel nut mounting surfaces and wheel mounting surfaces. 4. Apply 1-1/2 coats of Permahyd 1:1 Primer 4070. Mix 1:1 with Permahyd Hardener 3070 as per TDS. 5. Allow to flash for 30 minutes. 6. Apply two (2) coats of Permahyd 2:1 Surfacer 5080. Mix 2:1 with Permahyd Hardener 3071 as per TDS. 7. Bake for 60 minutes at 140°F (60°C) or allow to flash for 3 hours at 68°F (20°C). 8. Apply Permahyd Base Coat Series 280/285 as per TDS. 9. Allow to flash 10 to 15 minutes. 10. Apply 1 to 2 coats of Permacron High Solid Clear Coat 8060 as per TDS. 11. Allow to flash 10 minutes. Then bake at 140°F (60°C) for 40 minutes. For more information, contact your SPIES HECKER Jobber. We believe these sources and their products to be reliable. There may be additional manufacturers of such products. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or equipment from these firms or for any such items which may be available from other sources. Page 1435 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3184 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 2776 Catalytic Converter: Service and Repair Three-Way Converter Replacement REMOVE OR DISCONNECT - Raise the vehicle. 1. Clamps at the front and rear of the three-way catalytic converter. 2. Three-way catalytic converter to front exhaust pipe and three-way catalytic converter to intermediate exhaust pipe. 3. Three-way catalytic converter. INSTALL OR CONNECT 1. Three-way catalytic converter into the exhaust pipe. 2. New U-bolts and clamps at the front and rear of the three-way catalytic converter. Tighten nuts to 60 Nm (44 lbs. ft.). ^ Check for clearance and alignment. ^ Lower the vehicle. Page 209 Engine Control Module: Connector Views Engine Controls - Throttle Body Injection: C1 Pinout Description: C1 (Part 1 Of 2) Page 493 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2431 Disclaimer Page 1217 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3178 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Harness View Engine Page 3870 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 2724 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 86 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 520 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 569 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3412 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3041 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Locations Engine Page 2715 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 2906 Idle/Throttle Speed Control Unit: Service and Repair Throttle Body Assembly (Model 220) REMOVAL: - Remove the Idle Speed Control (ISC) Actuator and vacuum hose. - Remove ISC Actuator. INSTALLATION: - Install the ISC actuator and screws. - Connect vacuum hose. - Set activated idle speed. Refer to Adjustment Procedures. Specifications Temperature Vs Resistance Value Page 3912 Idle/Throttle Speed Control Unit: Adjustments Idle Speed Control Actuator Adjustment Procedure: - Before adjusting ISC actuator you must first check the minimum idle speed to be within specifications. Refer to SPECIFICATIONS/IDLE SPEED. (ISC actuator must have vacuum applied so that it is not contacting the throttle lever.) See image VIEW A. - Remove vacuum hose on ISC actuator on warm engine. - Adjust ISC actuated idle speed to 1300 +/- 50 rpm. See image VIEW B. - Install vacuum hose. Manifold Absolute Pressure (MAP) Sensor Engine Gauge Readings Are Inaccurate Oil Pressure Gauge: Testing and Inspection Gauge Readings Are Inaccurate 1. Remove lead from sensor, then connect tester J 33431-A or equivalent to sensor lead and ground. 2. If gauge responds accurately to tester, replace sensor. 3. If gauge does not respond accurately to tester, replace cluster. Page 990 Fig.1-Symbols (Part 1 Of 3) Page 1455 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2477 Distributor: Service and Repair Distributor Replacement Preassembled replacement distributors are not available. Components are available to assemble a new distributor. Some components, such as the air cleaner, may need to be removed to reach the distributor. The distributor has a separate ignition coil that mounts to a bracket on the top of the engine. REMOVE OR DISCONNECT Make sure the ignition switch is "OFF." 1. Air cleaner and hoses. 2. Electrical connectors at the side of the distributor cap. 3. Two screws on the sides of the distributor cap. 4. Ignition coil wire and spark plug wires on either the left or right side of the distributor. 5. Distributor cap and move it aside. A. Use chalk to note the position of the rotor in relation to the engine. B. Use chalk to note the position of the distributor housing in relation to the engine. 6. Distributor bolt and hold-down clamp. 7. Distributor. INSTALL OR CONNECT 1. Distributor. A. To ensure correct timing of the distributor, it must be installed with the rotor correctly positioned as noted in step 5 of the removal procedure. Line up the rotor to the mark on the engine, and the mark on the housing to the engine. B. If the distributor shaft won't drop into the engine, remove the distributor, insert a screwdriver into the hole for the distributor and rotate the oil pump driveshaft so it lines up with the distributor drive gear. 2. Hold-down clamp and bolt. Tighten Bolt to 27 Nm (20 lbs. in.). 3. Distributor cap with two screws. 4. Wiring harness connectors to the sealed ICM connectors at the side of the distributor. 5. Spark plug wires and coil wire. 6. Air cleaner and hoses. Check the ignition base timing. Page 3697 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 2600 Coolant Temperature Sensor/Switch (For Computer): Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1195 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1468 Page 3636 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2621 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 1567 5-Speed Manual Transmission W/4WD Page 3883 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3031 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1473 Fig.2-Symbols (Part 2 Of 3) Air Bag Disarming and Arming Air Bag(s) Arming and Disarming: Service and Repair Air Bag Disarming and Arming Disabling the SIR System Fig. 1 Air Bag Two-way Connector DRIVER SIDE Many service procedures require the air bag system to be disabled to prevent accidental deployment. The air bag system can maintain sufficient voltage to cause deployment for up to 2 minutes after the ignition switch is turned off, the battery ground cable is disconnected or the DERM fuse is removed. If the inflator module is disconnected from the deployment loop by the following procedure, service can begin immediately without waiting for the 2 minute time period to elapse. 1. Turn steering wheel so that vehicle wheels are pointed straight ahead. 2. Turn ignition switch to Lock position and remove key. 3. Remove air bag fuse from fuse block. 4. Remove steering column filler panel. 5. Remove Connector Position Assurance (CPA) and disconnect yellow two-way connector at base of steering column, Fig. 1. PASSENGER SIDE 1. Remove air bag fuse from fuse block. Enabling the SIR System Driver Side 1. Turn ignition switch to LOCK and remove key. 2. Connect yellow two-way connector and install connector position assurance (CPA). 3. Install steering column filler panel. 4. Insert air bag fuse into fuse block. 5. Turn ignition switch to RUN and verify that the air bag warning lamp flashes seven times then turns off. Passenger Side 1. Turn ignition switch to LOCK and remove key. 2. Insert air bag fuse into fuse block. 3. Turn ignition switch to RUN and verify that the air bag warning lamp flashes seven times then turns off. Page 679 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 769 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 826 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3928 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1046 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3511 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3312 Fig.2-Symbols (Part 2 Of 3) Page 2912 Ignition Control Module: Testing and Inspection IC SYSTEM DTC 12 is used during the "On-Board Diagnostic System Check" to test the code display ability of the control module. This DTC indicates that the control module is not receiving the engine rpm (Reference) signal. The "Reference" signal also triggers the fuel injection system. Without the "Reference" signal, the engine cannot operate. RESULTS OF INCORRECT IC OPERATION The control module uses information from the MAP and coolant sensors in addition to rpm to calculate spark advance as follows: - Low MAP output voltage = More spark advance - Cold Engine = More spark advance - High MAP output voltage = Less spark advance - Hot engine = Less spark advance Detonation can be caused by low MAP output or high resistance in the coolant sensor circuit. Poor performance can be caused by high MAP output or low resistance in the coolant sensor circuit. DTC 42 A fault in the IC system will usually set a DTC 42. Refer to DTC 42 in Computers and Controls / System Diagnosis. See: Computers and Control Systems/Testing and Inspection When the system is operating on the distributor module, there is no voltage on the bypass line and the module grounds the IC signal. The control module expects to find no voltage on the IC line during this condition. If voltage is found, a DTC 42 will set and the system will not go into the IC mode. When the rpm for IC is obtained (about 400 rpm), the control module applies 5 volts to the bypass line. The IC will no longer be grounded in the module and the IC voltage will be varying. If the bypass line is open, the module will not switch to test mode, so the IC voltage will be low and DTC 42 will be set. If the IC line is grounded, the module will switch to IC, there will be no IC signal and the engine will not operate. A DTC 42 may or may not set. An open in the IC circuit will set a DTC 42 and cause the engine to operate on the distributor module timing. This will cause poor performance and poor fuel economy. To check IC operation, place the vehicle in "Park" or "Neutral" and block the drive wheels. Start the engine and accelerate to 2000 rpm. Note the ignition timing. Disconnect the "Set Timing" connector and again note the timing. The timing will change if the IC system is operating. Specifications Catalytic Converter: Specifications Catalytic Converter Hanger Bolt 33 ft.lb Catalytic Converter to Exhaust Pipe Bolts 44 ft.lb Catalytic Converter U-Bolt Nuts 44 ft.lb Page 260 Fuel Pump Relay: Service and Repair Fuel Pump Relay REMOVE OR DISCONNECT 1. Protective cover. 2. Retainer, if installed. 3. Electrical connector. 4. Relay by depressing bracket clip at rear of relay, or removing bolts from retaining bracket. INSTALL OR CONNECT 1. Relay. 2. Electrical connector. 3. Retainer. 4. Protective cover. Page 851 Fig.1-Symbols (Part 1 Of 3) Engine Controls - Aftermarket Accessory Usage Engine Control Module: Technical Service Bulletins Engine Controls - Aftermarket Accessory Usage INFORMATION Bulletin No.: 04-06-04-054B Date: November 18, 2010 Subject: Info - Non-GM Parts and Accessories (Aftermarket) Models: 2011 and Prior GM Passenger Cars and Trucks Supercede: This bulletin is being revised to add model years and update to the new U.S. Fixed Operation Manager (FOM) and Canada Warranty Manager (WM) names. Please discard Corporate Bulletin Number 04-06-04-054A (Section 06 - Engine/Propulsion System). The recent rise and expansion of companies selling non-GM parts and accessories has made it necessary to issue this reminder to dealers regarding GM's policy on the use and installation of these aftermarket components. When a dealer is performing a repair under the New Vehicle Limited Warranty, they are required to use only genuine GM or GM-approved parts and accessories. This applies to all warranty repairs, special policy repairs or any repairs paid for by GM. Parts and accessories advertised as being "the same" as parts manufactured by GM, but not sold through GM, do not qualify for use in warranty repairs, special policy repairs or any repairs paid for by GM. During a warranty repair, if a GM original equipment part is not available through GM Customer Care and Aftersales (GM CC&A;), ACDelco(R) distributors, other GM dealers or approved sources, the dealer is to obtain comparable, non-GM parts and clearly indicate, in detail, on the repair order the circumstances surrounding why non-GM parts were used. The dealer must give customers written notice, prior to the sale or service, that such parts or accessories are not marketed or warranted by General Motors. It should also be noted that dealers modifying new vehicles and installing equipment, parts and accessories obtained from sources not authorized by GM are responsible for complying with the National Traffic and Motor Vehicle Safety Act. Certain non-approved parts or assemblies, installed by the dealer or its agent not authorized by GM, may result in a change to the vehicle's design characteristics and may affect the vehicle's ability to conform to federal law. Dealers must fully understand that non-GM approved parts may not have been validated, tested or certified for use. This puts the dealer at risk for potential liability in the event of a part or vehicle failure. If a GM part failure occurs as the result of the installation or use of a non-GM approved part, the warranty will not be honored. A good example of non-authorized modification of vehicles is the result of an ever increasing supply of aftermarket devices available to the customer, which claim to increase the horsepower and torque of the Duramax(TM) Diesel Engines. These include the addition of, but are not limited to one or more of the following modifications: - Propane injection - Nitrous oxide injection - Additional modules (black boxes) that connect to the vehicle wiring systems - Revised engine calibrations downloaded for the engine control module - Calibration modules which connect to the vehicle diagnostic connector - Modification to the engine turbocharger waste gate Although the installation of these devices, or modification of vehicle components, can increase engine horsepower and torque, they may also negatively affect the engine emissions, reliability and/or durability. In addition, other powertrain components, such as transmissions, universal joints, drive shafts, and front/rear axle components, can be stressed beyond design safety limits by the installation of these devices. General Motors does not support or endorse the use of devices or modifications that, when installed, increase the engine horsepower and torque. It is because of these unknown stresses, and the potential to alter reliability, durability and emissions performance, that GM has adopted a policy that prevents any UNAUTHORIZED dealer warranty claim submissions to any remaining warranty coverage, to the powertrain and driveline components whenever the presence of a non-GM (aftermarket) calibration is confirmed - even if the non-GM control module calibration is subsequently removed. Refer to the latest version of Bulletin 09-06-04-026 (V8 Gas Engines) or 06-06-01-007 (Duramax(TM) Diesel Engines) for more information on dealer requirements for calibration verification. These same policies apply as they relate to the use of non-GM accessories. Damage or failure from the use or installation of a non-GM accessory will not be covered under warranty. Failure resulting from the alteration or modification of the vehicle, including the cutting, welding or disconnecting of the vehicle's original equipment parts and components will void the warranty. Additionally, dealers will NOT be reimbursed or compensated by GM in the event of any legal inquiry at either the local, state or federal level that Page 3773 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3497 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1141 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1541 6. Connect the service harness connector to the actuator and connect the 2-pin connector to the mating connector at the axle. For 1994 to current models, in the case of a complete axle replacement, refer to Figure 1. 7. Route the wiring harness along the existing harness on the right side of the vehicle. Route CKT 241 (BRN) over the top and to the left of the transmission. Secure the harness using plastic ties. 8. For 1995-97 interim vehicles, locate the 4-wire connector (C120) on the left side of the transmission. Splice the BRN wire of the actuator harness into cavity D of CKT 241 (BRN) on the engine side of connector C120. Follow the splicing procedure described in Section 8A (Electrical Diagnosis Repair Procedures) of the applicable Service Manual. Important: The new Fast Axle Actuator requires only 1 splice. Page 3866 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Indicator Lamp Remains Illuminated Coolant Level Indicator Lamp: Testing and Inspection Indicator Lamp Remains Illuminated 1. Turn ignition switch to the On position, then check coolant level and add coolant as necessary. If lamp remains illuminated, proceed to step 2. 2. Disconnect electrical connector at the sensor. If lamp does not illuminate replace the sensor. If lamp remains illuminated, proceed to step 3. 3. Connect electrical lead to the sensor and check for an open circuit between the sensor and the module. Repair or replace as necessary. If circuit is satisfactory, replace the ECM. Page 1340 Knock Sensor: Description and Operation PURPOSE: The Knock Sensor (KS) is used to detect engine detonation (ping). OPERATION A 5 volt reference is applied to the knock sensor which has an internal resistance of about 3900 ohms. This resistance will lower the applied voltage to about half or 2.5 volts. When a knock is present, a small AC voltage is produced by the knock sensor and transmitted to the control module riding on top of the already existing 2.5 volts. An AC voltage monitor inside the control module will detect the knock and trigger the control module to start retarding the spark incrementally. A control module (ECM or PCM) is used in conjunction with one or two knock sensors to control detonation. A KS module will be found on ECM applications. On PCM application no KS module will be found as it is internal to the control module. Cruise Control Module Cruise Control Module: Description and Operation Cruise Control Module Fig. 1 Cruise Control Module. The cruise control module is mounted near the master cylinder on the engine side of the cowl. The module houses an electronic controller and an electric motor. Together, these components vary throttle position in response to cruise control mode selection. Page 1543 Page 30 For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon the module/component connection that the dielectric lubricant was applied to refer to the table above. Disclaimer Page 511 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Park/Neutral Position and Backup Lamp Switch Transmission Position Switch/Sensor: Locations Park/Neutral Position and Backup Lamp Switch HD Electronic 4-Speed Automatic Overdrive Transmission Page 3258 HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 435 Fig.2-Symbols (Part 2 Of 3) Page 1974 degradation. Important Regardless of the inflation media for tires (atmospheric air or nitrogen), inflation pressure maintenance of tires is critical for overall tire, and ultimately, vehicle performance. Disclaimer Page 2881 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Close-Couple Converter Replacement Catalytic Converter: Service and Repair Close-Couple Converter Replacement REMOVE OR DISCONNECT - Raise the vehicle. - Support intermediate exhaust pipe. 1. Oxygen sensor electrical connection (if equipped). 2. Nuts, springs, and flange gasket from exhaust manifold pipe. 3. Nuts and washers from rear exhaust pipe flange to intermediate pipe flange. 4. Catalytic converter assembly. INSTALL OR CONNECT Position catalytic converter to intermediate pipe. 1. Washers and nuts onto rear exhaust pipe flange studs. Tighten Nuts to 43 Nm (32 lbs. ft.). 2. Flange gasket, springs, and nuts to exhaust manifold. Tighten Nuts to 29 Nm (22 lbs. ft.). 3. Oxygen sensor electrical connection (if equipped). - Check for clearance and alignment. - Remove support from intermediate exhaust pipe. 4. Lower the vehicle. Page 3250 Electronic 4-Speed Automatic Overdrive Transmission W/4WD Specifications Compression Check: Specifications Minimum, 698 kPa (100 psi) @ 200 rpm. The lowest cylinder reading should not be less than 80% of the highest. Perform compression test with engine at normal operating temperature, spark plugs removed and throttle wide open. Page 1017 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 2291 Install a check valve oil filter; no other recommended actions at this time. Important: The previous actions are only applicable to short duration cold knock. These actions will not eliminate a knock occurring under load or a knock lasting for more than 10 seconds. Two main bearing procedures are recommended: 1. For main bearing replacement with the engine IN the vehicle: C, G, P, M and L vehicles 2. For main bearing replacement with the engine OUT OF the vehicle: K, S and T THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE IN THE VEHICLE Recommended for C, G, P, M and L vehicles. Important: A OEM training video has been produced for in-vehicle main bearing replacement procedure. One copy of the video will be sent to each dealer. If the video has not been received, contact XPRESS 1 Distribution Center at 1-800-783-3034. Main Bearing Clearance Determination and Installation Procedure 1. REMOVE THE SERPENTINE BELT, dipstick, dipstick tube and disconnect the negative battery cable. 2. Raise the vehicle and remove (or set aside) any parts restricting access to the oil pan bolts (i.e., starter motor, oil cooler lines, oil filter adapter, flywheel inspection cover). 3. Remove the oil pan, oil pump, and shield. 4. Remove # 5 (flange) bearing cap. Wipe the oil from the crankshaft journal and the lower main bearing insert. 5. Place a screw jack under an accessible part of the crankshaft, carefully apply pressure to the crankshaft to force it solidly against the top bearing insert. The reason for this is to remove any clearance between the top bearing insert and the crankshaft. If this step is not performed, a smaller than actual clearance will be measured. Important: This should be done as close as possible to the bearing being measured. This step is only required for on-vehicle service where the engine cannot be turned upside down as on an engine stand. 6. Place a piece of plastigage across the width of the lower bearing insert (parallel to the centerline of the crankshaft). 7. Reinstall # 5 main bearing cap. Torque to 110 N.m (80 lb ft). Do not allow crankshaft to turn. 8. Carefully remove the # 5 main bearing cap and bearing insert. The flattened plastigage will adhere to either the bearing insert or the crank journal. Do not remove the plastigage from the insert or journal. 9. On the edge of the plastigage envelope, there is a graduated scale. Without removing the flattened plastigage, measure its width at the widest point using the graduated scale on the plastigage envelope. 10. The desired main bearing clearance is 0.0008" - 0.0028". If the clearance measured with the plastigage is greater than 0.0028", write down the clearance. Next, read the back of the bearing insert to determine what size bearing was originally installed (usual STD, 0.0006", 0.0010" or 0.0012"). The size stamped on the bearing is the effective undersize when both inserts are installed. For example, a 0.0006" undersize bearing set consists of two (2) 0.0003" thicker bearing inserts, both stamped 0.0006". 11. Remove the top bearing insert using tool J 8080 and read the back to determine what size upper bearing insert was originally installed. The top insert may be different size than the bottom. 12. Calculate the original bearing undersize by dividing the size on each insert by 2, then add the values together. EXAMPLE 1: The lower insert is stamped 0.0006" and the upper is stamped 0.0010". Divide 0.0006" by two to get 0.0003". Divide 0.0010" by 2 to get 0.0005". Add 0.0003" and 0.0005" together to calculate the bearing undersize, which is 0.0008" in this case. Page 528 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Specifications Manifold Absolute Pressure (MAP) Sensor: Specifications 1,000 to 2,000 Feet ............................................................................................................................. ........................................................... 3.6 to 5.2 Volts 2,000 to 3,000 Feet ........................................ ................................................................................................................................................ 3.5 to 5.1 Volts 3,000 to 4,000 Feet .............................................................................................................. .......................................................................... 3.3 to 5.0 Volts 4,000 to 5,000 Feet ......................... .............................................................................................................................................................. . 3.2 to 4.8 Volts 5,000 to 6,000 Feet .................................................................................................. ...................................................................................... 3.0 to 4.6 Volts 6,000 to 7,000 Feet ............. .............................................................................................................................................................. ............. 2.9 to 4.5 Volts 7,000 to 8,000 Feet ...................................................................................... .................................................................................................. 2.8 to 4.3 Volts 8,000 to 9,000 Feet . .............................................................................................................................................................. ......................... 2.6 to 4.2 Volts 9,000 to 10,000 Feet ........................................................................ .............................................................................................................. 2.5 to 4.0 Volts Page 3622 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1414 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1290 The existing labor operation (E7200) has been changed to include "Add" conditions for cylinders that will not rotate. New Tumblers New tumblers are available from GMSPO for recoding lock cylinders that use double-sided reversible keys. These new tumblers should be used immediately and information about the disposition of original tumblers will be provided by GMSPO. Figure 1 shows the new tumbler profile. The shaded area was part of the original tumbler profile, and is removed on the new tumblers. The new part numbers for the tumblers are as follows: Part No. 2852732 = Tumbler # 1 Part No. 2852733 = Tumbler # 2 Part No. 2852734 = Tumbler # 3 Part No. 2852735 = Tumbler # 4 Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. New Procedures For Seized/Won't Rotate Column Mounted Ign. CYL. Page 2540 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 2626 Coolant Temperature Sensor/Switch (For Computer): Description and Operation Engine Coolant Temperature (ECT) Sensor PURPOSE The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40° C (-40° F) while high temperature causes low resistance (70 ohms at 130° C (266° F). OPERATION The control module supplies a 5 volt signal to the ECT sensor through a resistor in the control module and measures the voltage. The voltage will be high when the engine is cold, and low when the engine is hot. Engine coolant temperature affects most systems controlled by the control module. Page 3514 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 443 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 581 Oil Pressure Switch Page 3335 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1774 PARTS INFORMATION WARRANTY INFORMATION Page 1044 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Stepper Motor Cruise Control - Will Not Resume/Reset Cruise Control Module: Customer Interest Stepper Motor Cruise Control - Will Not Resume/Reset FILE IN SECTION: 9 - Accessories BULLETIN NO.: 56-90-02A DATE: July, 1995 SUBJECT: Stepper Motor Cruise Control will not Resume or Reset (Replace SMCC Module) MODELS: 1993-95 Chevrolet Camaro 1993-95 Pontiac Firebird with 3.4L V6 Engine (VIN S - RPO L32) and Automatic Transmission (M30) only OR with 5.7L V8 Engine (VIN P - RPO LT1) and any Transmission 1994-95 Chevrolet and GMC Truck C/K, S/T, M/L Models This bulletin is being revised to add F car information. Please discard Corporate Bulletin Number 56-90-02 (Section 9 - Accessories). CONDITION Some owners may comment that the Stepper Motor Cruise Control (SMCC) will intermittently cut out and will not resume or reset unless the ignition key is cycled. CAUSE The SMCC is sensitive to any brake switch contact bounce of less than 32 milliseconds. This contact bounce may cause the SMCC to go into a diagnostic shut down mode until the module is reset by turning the ignition off. For trucks, the 1994 Zero Adjust Brake switches tend to aggravate this sensitivity. CORRECTION Replace the SMCC module only if the diagnosis in the Service Manual, Section 8A Cruise Control does not resolve the concern. Service Procedure For 1994-95 Chevrolet and GMC Truck C/K, S/T, M/L Models: Follow the SMCC MODULE remove and install procedure using the appropriate service manual. For F-car models, use the following procedure. Remove Before removing cruise control module, disconnect cruise control cable to obtain the necessary clearance. 1. Disconnect cruise control cable end fitting from throttle body lever stud. If vehicle is equipped with accelerator control/cruise control cable adjuster (throttle relaxer), remove cruise control cable end fitting from adjuster. Note location of pulley for end fitting. 2. Unlock cruise control cable conduit by pulling up on unlock button. 3. Push conduit together to obtain the additional cable slack. 4. Remove cruise control module per Section 9B of the Service Manual. Important: It is not necessary to remove cruise control cable from vehicle. Install 1. Install cruise control cable to cruise control module per Section 9B of the Service Manual, Page 557 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 2982 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3591 Spark Plug: Application and ID Spark Plug Coding Spark Plug Codeing Legend DESCRIPTION Resistor-type, tapered-seat spark plugs are used on this engine. No gasket is used on these spark plugs. A dot before the spark plug code or the letter "C" after the number in the code indicates the spark plug has a copper core. Refer to Specification / Mechanical or to the vehicle emissions control information label for correct gap information. Page 85 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 1401 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 583 Oil Pressure Switch (For Fuel Pump): Service and Repair Oil Pressure Switch REMOVE OR DISCONNECT 1. Electrical connector. 2. Oil pressure switch using wrench J 35748. INSTALL OR CONNECT 1. Oil pressure switch. 2. Electrical connector. Page 997 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1174 Throttle Position Sensor: Locations Component View Throttle Position (TP) Sensor The Throttle Position (TP) Sensor is attached to the right hand side of the throttle body. Page 3755 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3358 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1690 Valve Clearance: Specifications Valve Arrangement FRONT TO REAR 7.4L/V8-454 ......................................................................................................................................... ........................................................... E-I-E-I-E-I-E-I Page 989 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3931 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3657 Fig.2-Symbols (Part 2 Of 3) Page 3745 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3291 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 94 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1857 - Support the GM Oil Life System, thereby minimizing the replacement of engine oil, before its life has been depleted. - Reduce the duplication of requirements for a large number of internal GM engine oil specifications. International Lubricants Standardization and Approval Committee (ILSAC) GF-5 Standard In addition to GM dexos 1(TM), a new International Lubricants Standardization and Approval Committee (ILSAC) standard called GF-5, was introduced in October 2010. - There will be a corresponding API category, called: SN Resource Conserving. The current GF-4 standard was put in place in 2004 and will become obsolete in October 2011. Similar to dexos 1(TM), the GF-5 standard will use a new fuel economy test, Sequence VID, which demands a statistically significant increase in fuel economy versus the Sequence VIB test that was used for GF-4. - It is expected that all dexos 1(TM) approved oils will be capable of meeting the GF-5 standard. However, not all GF-5 engine oils will be capable of meeting the dexos 1(TM) specification. - Like dexos(TM), the new ILSAC GF-5 standard will call for more sophisticated additives. The API will begin licensing marketers during October 2010, to produce and distribute GF-5 certified products, which are expected to include SAE 0W-20, 0W-30, 5W-20, 5W-30 and 10W-30 oils. Corporate Average Fuel Economy (CAFE) Requirements Effect on Fuel Economy Since CAFE standards were first introduced in 1974, the fuel economy of cars has more than doubled, while the fuel economy of light trucks has increased by more than 50 percent. Proposed CAFE standards call for a continuation of increased fuel economy in new cars and trucks. To meet these future requirements, all aspects of vehicle operation are being looked at more critically than ever before. New technology being introduced in GM vehicles designed to increase vehicle efficiency and fuel economy include direct injection, cam phasing, turbocharging and active fuel management (AFM). The demands of these new technologies on engine oil also are taken into consideration when determining new oil specifications. AFM for example can help to achieve improved fuel economy. However alternately deactivating and activating the cylinders by not allowing the intake and exhaust valves to open contributes to additional stress on the engine oil. Another industry trend for meeting tough fuel economy mandates has been a shift toward lower viscosity oils. dexos 1(TM) will eventually be offered in several viscosity grades in accordance with engine needs: SAE 0W-20, 5W-20, 0W-30 and 5W-30. Using the right viscosity grade oil is critical for proper engine performance. Always refer to the Maintenance section of a vehicle Owner Manual for the proper viscosity grade for the engine being serviced. GM Oil Life System in Conjunction With dexos (TM) Supports Extended Oil Change Intervals To help conserve oil while maintaining engine protection, many GM vehicles are equipped with the GM Oil Life System. This system can provide oil change intervals that exceed the traditional 3,000 mile (4,830 km) recommendation. The dexos (TM) specification, with its requirements for improved oil robustness, compliments the GM Oil Life System by supporting extended oil change intervals over the lifetime of a vehicle. If all GM customers with GM Oil Life System equipped vehicles would use the system as intended, GM estimates that more than 100 million gallons of oil could be saved annually. GM dexos 2(TM) Information Center Website Refer to the following General Motors website for dexos 2(TM) information about the different licensed brands that are currently available: http://www.gmdexos.com GM dexos 2(TM) Engine Oil Trademark and Icons Locations Engine Page 3176 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1226 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 2852 Pinout Description: C2 (Part 1 Of 2) Pinout Description: C2 (Part 2 Of 2) Page 3182 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3628 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 2901 Fuel Pump Relay: Service and Repair Fuel Pump Relay REMOVE OR DISCONNECT 1. Protective cover. 2. Retainer, if installed. 3. Electrical connector. 4. Relay by depressing bracket clip at rear of relay, or removing bolts from retaining bracket. INSTALL OR CONNECT 1. Relay. 2. Electrical connector. 3. Retainer. 4. Protective cover. Page 3423 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 959 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 3249 Transmission Position Switch/Sensor: Locations Park/Neutral Position and Backup Lamp Switch, With 4WD HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 817 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 165 Engine Control Module: Technical Service Bulletins PCM - Replacement Component Text Deletion File in Section: 6E - Engine Fuel & Emission Bulletin No.: 41-65-33 Date: October, 1994 SERVICE MANUAL UPDATE Subject: Section 3A - Driveability, Emissions and Electrical Diagnosis - Text Deletion Models: 1994 Chevrolet and GMC Truck & T Models with 2.2L Gasoline Engine (VIN 4 - RPO LN2) or 4.3L Engine (VINs Z, W - RPOs LB4, L35) 1994-95 Chevrolet and GMC Truck C/K, M/L, G, P3, PG Models with 4.3L Engine (VIN Z - RPO LB4), 5.0L Engine (VIN H - RPO L03), 5.7L Engine VIN K - RPO L05) or 7.4L Engine (VIN N - RPO L19) 1994-95 Chevrolet and GMC Truck C/K, G, P3 Models with 6.5L Diesel Engine (VINs F, P, S RPOs L65, L49, L56) This bulletin contains revisions to the "Driveability, Emissions and Electrical Diagnostic" Service Manuals for the following pages: 1994 S/T Truck - 3A-5 1994-1995 G Van - 3A-4 1994-1995 C/K Truck - 3A-4 1994-1995 M/L Truck - 3A-4 1994-1995 PG/P3 Truck - 3A-4 1994-1995 C/K, G, P Truck - 3-17 and Supplement This Text is to be Deleted "The replacement PCM may be faulty - After the PCM is replaced, the system should be rechecked for proper operation. If the Diagnostic Chart again indicates that the PCM is the problem, substitute a known good PCM". Engine, A/T - Shift/Driveability Concerns/MIL ON Air Filter Element: Customer Interest Engine, A/T - Shift/Driveability Concerns/MIL ON Bulletin No.: 04-07-30-013B Date: February 01, 2007 INFORMATION Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007 HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X Supercede: This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 04-07-30-013A (Section 07 - Transmission/Transaxle). The use of an excessively/over-oiled aftermarket, reusable air filter may result in: Service Engine Soon (SES) light on Transmission shift concerns, slipping and damaged clutch(es) or band(s) Engine driveability concerns, poor acceleration from a stop, limited engine RPM range The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur. When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared to a like vehicle with an OEM air box and filter under the same driving conditions to verify the concern. The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty. If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and the air induction hose for contamination of oil prior to making warranty repairs. Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not considered to be warrantable repair items. Page 2534 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Harness View Engine Page 486 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 875 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1321 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 841 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 894 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Service and Repair Push Rod: Service and Repair When a replacement pushrod has a paint stripe at one end, this painted end must be installed in contact with the rocker arm. To provide durability a hardened insert is incorporated in the rocker arm end of these pushrods. Specifications Intake Air Temperature Sensor: Specifications Torque Valve Torque Valve Induction Air Sensor 44 in.lb Page 2806 Engine Control Module: Technical Service Bulletins PCM - Replacement Component Text Deletion File in Section: 6E - Engine Fuel & Emission Bulletin No.: 41-65-33 Date: October, 1994 SERVICE MANUAL UPDATE Subject: Section 3A - Driveability, Emissions and Electrical Diagnosis - Text Deletion Models: 1994 Chevrolet and GMC Truck & T Models with 2.2L Gasoline Engine (VIN 4 - RPO LN2) or 4.3L Engine (VINs Z, W - RPOs LB4, L35) 1994-95 Chevrolet and GMC Truck C/K, M/L, G, P3, PG Models with 4.3L Engine (VIN Z - RPO LB4), 5.0L Engine (VIN H - RPO L03), 5.7L Engine VIN K - RPO L05) or 7.4L Engine (VIN N - RPO L19) 1994-95 Chevrolet and GMC Truck C/K, G, P3 Models with 6.5L Diesel Engine (VINs F, P, S RPOs L65, L49, L56) This bulletin contains revisions to the "Driveability, Emissions and Electrical Diagnostic" Service Manuals for the following pages: 1994 S/T Truck - 3A-5 1994-1995 G Van - 3A-4 1994-1995 C/K Truck - 3A-4 1994-1995 M/L Truck - 3A-4 1994-1995 PG/P3 Truck - 3A-4 1994-1995 C/K, G, P Truck - 3-17 and Supplement This Text is to be Deleted "The replacement PCM may be faulty - After the PCM is replaced, the system should be rechecked for proper operation. If the Diagnostic Chart again indicates that the PCM is the problem, substitute a known good PCM". Engine - Noise/Damage Oil Filter Application Importance Oil Filter: All Technical Service Bulletins Engine - Noise/Damage Oil Filter Application Importance INFORMATION Bulletin No.: 07-06-01-016B Date: July 27, 2009 Subject: Information on Internal Engine Noise or Damage After Oil Filter Replacement Models: 2010 and Prior Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X Supercede: This bulletin is being updated to add model years. Please discard Corporate Bulletin Number 07-06-01-016A (Section 06 - Engine/Propulsion System). Important Engine damage that is the result of an incorrect or improperly installed engine oil filter is not a warrantable claim. The best way to avoid oil filter quality concerns is to purchase ACDelco(R) oil filters directly from GMSPO. Oil filter misapplication may cause abnormal engine noise or internal damage. Always utilize the most recent parts information to ensure the correct part number filter is installed when replacing oil filters. Do not rely on physical dimensions alone. Counterfeit copies of name brand parts have been discovered in some aftermarket parts systems. Always ensure the parts you install are from a trusted source. Improper oil filter installation may result in catastrophic engine damage. Refer to the appropriate Service Information (SI) installation instructions when replacing any oil filter and pay particular attention to procedures for proper cartridge filter element alignment. If the diagnostics in SI (Engine Mechanical) lead to the oil filter as the cause of the internal engine noise or damage, dealers should submit a field product report. Refer to Corporate Bulletin Number 02-00-89-002I (Information for Dealers on How to Submit a Field Product Report). Disclaimer Page 2980 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 907 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1315 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2567 Heater And A/C Control Select SW (C2), Stop Lamp & TCC Switch Jumper, Aux Fan Control SW Page 1490 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 3419 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3882 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1147 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3751 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 494 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1243 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2730 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3478 4. Locate the surface for the cylinder release button on the plastic ignition switch housing and center punch a location on the "rib" approximately 3/8" rearward (toward the key entry end) from the cylinder release button, see Figure 3. 5. Using a 1/8" drill bit, carefully drill a pilot hole through the plastic housing only. 6. Using a 9/32" drill bit, carefully drill a larger hole at the pilot location, and slightly into the lock cylinder surface to break the release button retaining spring. 7. Remove portions of the broken spring from the hole using a small pair of needle nose pliers (or other suitable tool) and turn switch over to shake out the release button. 8. Grasp the lock cylinder, remove it from the switch housing. 9. Remove any plastic "flash" from the drilling operations and, using compressed air, blow out the ignition switch assembly. 10. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 11. Install the new cylinder(s) as required by rotating both the cylinder and ignition switch to the "ON" position and pushing the cylinder into the switch. It may be necessary to depress the release button slightly as it passes by the 9/32" hole previously drilled in the housing. 12. Reassemble the ignition switch and instrument panel components as indicated by the appropriate Service Manual. Page 1546 ^ For 1994 vehicles, splice into CKT 50 (BRN) between connector C152 and P101 (Figures 5, 6). Page 3233 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2872 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Wheels/Tires - Use of Nitrogen Gas in Tires Tires: All Technical Service Bulletins Wheels/Tires - Use of Nitrogen Gas in Tires INFORMATION Bulletin No.: 05-03-10-020C Date: April 27, 2010 Subject: Use of Nitrogen Gas in Tires Models: 2011 and Prior GM Passenger Cars and Trucks (including Saturn) 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 05-03-10-020B (Section 03 - Suspension). GM's Position on the Use of Nitrogen Gas in Tires General Motors does not oppose the use of purified nitrogen as an inflation gas for tires. We expect the theoretical benefits to be reduced in practical use due to the lack of an existing infrastructure to continuously facilitate inflating tires with nearly pure nitrogen. Even occasional inflation with compressed atmospheric air will negate many of the theoretical benefits. Given those theoretical benefits, practical limitations, and the robust design of GM original equipment TPC tires, the realized benefits to our customer of inflating their tires with purified nitrogen are expected to be minimal. The Promise of Nitrogen: Under Controlled Conditions Recently, nitrogen gas (for use in inflating tires) has become available to the general consumer through some retailers. The use of nitrogen gas to inflate tires is a technology used in automobile racing. The following benefits under controlled conditions are attributed to nitrogen gas and its unique properties: - A reduction in the expected loss of Tire Pressure over time. - A reduction in the variance of Tire Pressures with temperature changes due to reduction of water vapor concentration. - A reduction of long term rubber degradation due to a decrease in oxygen concentrations. Important These are obtainable performance improvements when relatively pure nitrogen gas is used to inflate tires under controlled conditions. The Promise of Nitrogen: Real World Use Nitrogen inflation can provide some benefit by reducing gas migration (pressure loss) at the molecular level through the tire structure. NHTSA (National Highway Traffic Safety Administration) has stated that the inflation pressure loss of tires can be up to 5% a month. Nitrogen molecules are larger than oxygen molecules and, therefore, are less prone to "seeping" through the tire casing. The actual obtainable benefits of nitrogen vary, based on the physical construction and the materials used in the manufacturing of the tire being inflated. Another potential benefit of nitrogen is the reduced oxidation of tire components. Research has demonstrated that oxygen consumed in the oxidation process of the tire primarily comes from the inflation media. Therefore, it is reasonable to assume that oxidation of tire components can be reduced if the tire is inflated with pure nitrogen. However, only very small amounts of oxygen are required to begin the normal oxidation process. Even slight contamination of the tire inflation gas with compressed atmospheric air during normal inflation pressure maintenance, may negate the benefits of using nitrogen. GM Tire Quality, Technology and Focus of Importance Since 1972, General Motors has designed tires under the TPC (Tire Performance Criteria) specification system, which includes specific requirements that ensure robust tire performance under normal usage. General Motors works with tire suppliers to design and manufacture original equipment tires for GM vehicles. The GM TPC addresses required performance with respect to both inflation pressure retention, and endurance properties for original equipment tires. The inflation pressure retention requirements address availability of oxygen and oxidation concerns, while endurance requirements ensure the mechanical structure of the tire has sufficient strength. This combination has provided our customers with tires that maintain their structural integrity throughout their useful treadlife under normal operating conditions. Regardless of the inflation media for tires (atmospheric air or nitrogen), inflation pressure maintenance of tires is critical for overall tire, and ultimately, vehicle performance. Maintaining the correct inflation pressure allows the tire to perform as intended by the vehicle manufacturer in many areas, including comfort, fuel economy, stopping distance, cornering, traction, treadwear, and noise. Since the load carrying capability of a tire is related to inflation pressure, proper inflation pressure maintenance is necessary for the tire to support the load imposed by the vehicle without excessive structural Page 282 Air Bag Control Module: Service and Repair Prior to performing replacement procedures, disarm air bag system. Refer to, Service and Repair/ Air Bag System Disarming & Air Bag System Arming. Refer to, / Specifications/ Mechanical for torque values when installing components. All sensors and mounting bracket bolts must be carefully torqued to assure proper operation. Never power up the air bag system when any sensor is not rigidly attached to the vehicle, since the sensor could be activated when not attached, causing air bag deployment. Do not open DERM case for any reason. Touching connector pins or soldered components may cause electrostatic discharge damage. Repair of a malfunctioning DERM is by replacement only. 1. Remove DERM from mounting bracket. 2. Remove Connector Position Assurance (CPA) lock, then disconnect DERM electrical connector from DERM. 3. Reverse procedure to install. Page 2514 Coolant Level Indicator Lamp: Testing and Inspection Indicator Lamp Will Not Illuminate 1. Turn ignition switch to the crank position, and proceed as follows: a. If lamp illuminates, lamp is satisfactory and connector is properly installed. Proceed to step 2. b. If lamp does not illuminate, check bulb, socket and wiring between socket and module connector. Replace or repair as necessary. 2. Turn ignition switch to the On position and disconnect electrical lead at coolant level sensor mounted on the radiator. If lamp fails to illuminate, check wiring between coolant level sensor connector and ECM for a short circuit to ground. If circuit is satisfactory, replace the ECM. Page 248 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 999 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3873 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3670 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Diagrams Engine Coolant Level Indicator Module Page 3736 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3520 Knock Sensor Circuit CIRCUIT DESCRIPTION The Knock Sensor (KS) system consist of a knock sensor with one wire that goes directly to the PCM. There is a check performed by the PCM. The check consist of monitoring CKT 496 for a voltage that is more than 0.04 volt and less than 4.6 volts. If the voltage is either too high or too low for 16 or more seconds, DTC 43 will set. CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic chart. 1. The first test is to determine if the system is functioning at the present time. 2. Test two determines the state of the 5 volt reference voltage applied to the knock sensor circuit. DIAGNOSTIC AIDS The PCM applies 5 volts to CKT 496. A 3900 ohm resistor in the knock sensor reduces the voltage to about 2.5 volts. When knock occurs, the knock sensor produces a small AC voltage that rides on top of the 2.5 volts already applied. An AC voltage monitor, in the PCM, is able to read this signal as knock and incrementally retard spark. If the KS system checks OK, but detonation is the complaint, refer to Diagnosis By Symptom / Detonation, Spark Knock See: Computers and Control Systems/Testing and Inspection/Symptom Related Diagnostic Procedures/Detonation/ Spark Knock Page 472 Fig.2-Symbols (Part 2 Of 3) Page 3707 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3683 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3947 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 2671 Temperature Gauge: Testing and Inspection Gauge Indicates Hot When Engine Is Cold This condition is generally caused by a shorted or grounded circuit. 1. Remove sensor lead at sensor unit. Gauge should move to COLD position, if not check unit for a external short. If no external short is found, replace sensor. 2. If gauge stays HOT, check for a short circuit in gauge to sensor wiring. If circuit is satisfactory, replace cluster. Page 1923 Underhood Fuse - Relay Center Page 861 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3367 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3678 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3122 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 2953 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2306 Bulletin No.: 56-43-02 For reference purposes, Figure 1 shows a layout of the front drive system. Proper Labor Operation Usage If the replacement of the front axle output shaft seal(s) becomes necessary and the vehicle and repair are subject to the applicable warranty, only the following Labor Operation should be used: F1440: Seals Front Differential Output Shaft - Replace Right F1441: Seals Front Differential Output Shaft - Replace Left F1447: Seals Front Differential Output Shaft - Replace Both Important: This labor operation includes the time needed for removal and replacement of the front drive axle (halfshaft). DO NOT submit an additional claim for Front Drive Halfshaft R & R. Proper Drive Axle (Halfshaft) Handling to Prevent Inboard and Outboard Boot Damage When performing the output shaft seal replacement procedure described in the service manual, precautions should be taken to prevent damage to the inboard and outboard drive axle (halfshaft) boots (seals). The boots (seals) are delicate and critical to the performance of the halfshaft. Take the following precautions when performing the procedure: Page 1599 Important When performing adjustments to vehicles requiring a 4-wheel alignment, set the rear wheel alignment angles first in order to obtain proper front wheel alignment angles. Perform the following steps in order to measure the front and rear alignment angles: 1. Install the alignment equipment according to the manufacturer's instructions. 2. Jounce the front and the rear bumpers 3 times prior to checking the wheel alignment. 3. Measure the alignment angles and record the readings. If necessary, adjust the wheel alignment to vehicle specification and record the before and after measurements. Refer to Wheel Alignment Specifications in SI. Important Technicians must refer to SI for the correct wheel alignment specifications. SI is the only source of GM wheel alignment specifications that is kept up-to-date throughout the year. Test drive vehicle to ensure proper repair. Page 801 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2572 Fan Blade: Vehicle Damage Warnings WARNING: Do not operate engine until fan has first been inspected for cracks and/or separations. If a fan blade is found to be bent or damaged in any way, do not attempt to repair or reuse damaged part. Proper balance is essential in fan assembly operation. Balance cannot be assured once a fan assembly has been found to be bent or damaged and failure may occur during operation, creating an extremely dangerous condition. Always replace damaged fan assembly. Page 1001 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 2968 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3187 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3359 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 496 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. A/C Compressor - Loud Knocking Noise Refrigerant Filter: All Technical Service Bulletins A/C Compressor - Loud Knocking Noise File in Section: 1 - HVAC Bulletin No.: 56-12-01 Date: February, 1995 SUBJECT: Loud Knock from A/C Compressor (Replace Compressor and Thermal Expansion Valve) MODELS: 1994-95 Chevrolet C/K Models built before VIN breakpoint SJ300349 1994-95 GMC Truck C/K Models built before VIN breakpoint SJ701253 with Rear A/C (RPO C69) or Rear Heater and A/C (RPOs C36, C69) CONDITION Some owner's of the above listed vehicles may comment that the A/C compressor has developed a loud knocking noise. The A/C system will continue to cool. CAUSE When the rear A/C system is shut off, a refrigerant flood back condition may occur through the rear A/C system. This flooding degreases the internal parts of the compressor resulting in rapid slider block wear and the resulting loud knocking noise. A poor contact between the TXV capillary tube and the rear evaporator outlet tube can allow the TXV to remain open when the rear system is not in use. The open TXV may allow liquid refrigerant to flood back through the rear system (liquid line, TXV, evaporator, rear suction line) and subsequently flood the compressor. CORRECTION Replace the A/C compressor, the thermal expansion valve (TXV), and add an in-line filter. Service Procedure 1. Recover the R-134a refrigerant charge (Section 1-B of Service Manual). 2. Replace the compressor and balance the PAG lubricant in the system following the procedures in the vehicle service manual. 3. Install an in-line filter in the liquid line after the condenser and before the "Y" in the line separating the front and rear systems. 4. Remove, inspect and clean the orifice tube for the front system. It is located in the liquid line after the "Y" joint. 5. Replace the orifice tube. 6. Disconnect seat belt and remove rear bench seat. 7. Remove the right second passenger seat shoulder belt retainer from the right side C-pillar. 8. Remove the (5) screws from the right side C-pillar trim. 9. Remove the (2) screws securing the right side lower trim panel to the C-pillar. 10. Remove the (5) screws securing the D-pillar covers. 11. Lift the right side lower trim panel and roll forward to remove, this exposes the rear HVAC evaporator case module. Page 508 Fig.1-Symbols (Part 1 Of 3) Page 1433 Fig.2-Symbols (Part 2 Of 3) Page 395 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Component Locations Fuse Block: Component Locations Convenience Center IP Fuse Block Lower LH side of I/P Page 252 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3788 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 813 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3228 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Harness View Engine Page 2523 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 964 Manifold Absolute Pressure (MAP) Sensor: Description and Operation MAP Sensor PURPOSE The Manifold Absolute Pressure (MAP) sensor is a pressure sensitive variable resistor. It measures the changes in the intake manifold pressure which result from engine load and speed changes, and converts this to a voltage output. The computer uses this voltage output to control fuel delivery and ignition timing. OPERATION A closed throttle on engine coastdown would produce a relatively low MAP voltage output, while a wide open throttle would produce a high voltage output. Manifold absolute pressure is the OPPOSITE of vacuum. When manifold pressure is high, vacuum is low. The MAP sensor is also used to measure barometric pressure under certain conditions, which allows the control module to automatically adjust to different altitudes. The control module sends a 5 volt reference signal to the MAP sensor. As manifold pressure changes, electrical resistance of the sensor also changes. By monitoring the sensor output voltage, the control module knows the manifold pressure. A high pressure, low vacuum (high voltage) condition requires more fuel, while a low pressure, high vacuum (low voltage) requires less fuel. The control module used the MAP sensor to control fuel delivery and ignition timing. Page 1054 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Specifications Transmission Speed Sensor: Specifications COMPONENT ..................................................................................................................................... ...................................................... Torque/Ft.Lbs. Speed Sensor To Case Screw ............................. .............................................................................................................................................................. .... 8 Page 3925 Knock Sensor Page 3130 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 3871 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3946 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1245 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Main Bearing Torque Specifications Crankshaft: Specifications Main Bearing Cap Main Bearing Cap Torque Specification 100 ft.lb Page 3521 Knock Sensor: Service and Repair REMOVE OR DISCONNECT 1. Negative battery cable. 2. Drain cooling system. NOTE: On knock sensors which are mounted in the end of the cylinder head draining the cooling system will not be necessary. 3. Wiring harness connector from knock sensor. 4. Knock sensor from cylinder head or block. INSTALL OR CONNECT 1. Knock sensor into cylinder head or block. Apply water base caulk to sensor threads. Do not use silicon tape as this will insulate sensor from engine block. Tighten to 19 Nm (14 lb. ft.). 2. Wiring harness connector to the knock sensor. 3. Negative battery cable. 4. Refill cooling system if required. Page 195 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3705 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 867 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 2896 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 2074 Painting Process System: Dupont Products Paint Color Information: Corsican Silver WA EQ9283 Dupont # C9143, Sparkle Silver WA9967 Dupont # C9339 1. Wipe wheel with cleaning solvent: 3939-S, 3949-S or 3900-S. 2. Mask off tires. Important: 3. Mask off all wheel mounting surfaces and wheel mount surfaces. 4. Apply two coats of 615/616-S etching primer to wheel allowing 10 minutes flash between coats. Allow to dry for 30 minutes before applying primer coat. 5. Apply URO 5000 primer 1220/193-S + accelerator 389-S using two coats at 65-70 PSI at the gun. Allow 12-15 minutes between coats. Force bake 30 minutes at 140°F (60°C). 6. Scuff sand using green Scotch-Brite pad. 7. Solvent wipe before top coating. 8. Apply IMRON 6000 base coat to wheel. 2-3 coats to hiding at 60-70 PSI allowing to flash between coats. Base coat needs to dry 20-30 minutes before clearcoat is applied. 9. Apply 3440-S clearcoat to wheel using two coats at 60-70 PSI. Flash 10-15 minutes between coats. 389-S can be used in basecoat and clearcoat to give faster set up times. 10. Allow overnight dry before reassemble. Can be baked for 30 minutes at 140°F (60°C). Attachment 2 - PPG Products Painting Process: PPG System Paint Color Information: Corsican Silver WAEQ9283; PPG # DBC-3531, Sparkle Silver WA9967; PPG # 35367 1. Wash entire wheel with aluminum cleaner DX533, mix 1:3 with water. Allow to react 2-3 minutes and rinse thoroughly. 2. Wash entire wheel with aluminum conditioner DX5O3 straight from the container. Allow to react 2-3 minutes until pale gold or tan color develops. Rinse thoroughly and dry. 3. Mask off tires. Important: 4. Mask off all wheel nut mounting surfaces and wheel mounting surfaces. 5. Apply 1-2 coats of DP Primer and allow to flash for 15-20 minutes. 6. Apply 2-3 coats of Deltron Basecoat (DBC) and allow to flash 20 minutes after the final coat. 7. Apply two (2) wet coats of Concept 2001 Acrylic urethane. 8. Flash 20 minutes and bake 140°F (60°C) for 30 minutes. For more information contact your PPG Jobber. Attachment 3 - Spies Hecker Painting Process: Spies Hecker System Paint Color Information: Corsican Silver AWEQ9283; SH-72913, Sparkle Silver WA9967; SH-71912 1. Clean with Permahyd Silicone Remover 7090. 2. Mask off tires. Service and Repair Vehicle Lifting: Service and Repair Fig. 13 Vehicle Lift Points. Fig. 13 Vehicle Lift Points. Page 3905 Idle Speed/Throttle Actuator - Mechanical: Testing and Inspection ISC Check Page 677 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Locations Engine Page 193 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1819 Coolant: Technical Service Bulletins Extended Life Engine Coolant - DEX-COOL(TM) FILE IN SECTION: 6 - Engine BULLETIN NO.: 53-62-01 DATE: June, 1995 SUBJECT: New Extended Life Engine Coolant Known as DEX-COOL(TM) MODELS: 1995 Passenger Cars and Trucks A new extended life engine coolant known as "DEX-COOL(TM)" will be used in all General Motors vehicles. Some trucks will be filled with DEX-COOL TM beginning in late May; most vehicles will convert in July, 1995 with the remaining vehicles to convert by January, 1996. Most of these vehicles will be 1995 models. All production for 1996 models will utilize DEX-COOL(TM). It is imperative to note the following about DEX-COOL(TM) engine coolant: ^ IT IS ORANGE IN COLOR TO DISTINGUISH IT FROM CONVENTIONAL COOLANT. ^ THE SERVICE CHANGE INTERVAL ON VEHICLES WHICH ARE BUILT WITH DEX-COOL(TM) IS 5 YEARS/100,000 MILES, WHICHEVER OCCURS FIRST. ^ TO MAINTAIN FULL CORROSION PROTECTION DURABILITY, DEX-COOL (TM) MUST NOT BE MIXED WITH CONVENTIONAL (CONTAINING SILICATE) ENGINE COOLANTS. ^ DEX-COOL(TM) IS AN ETHYLENE GYLCOL BASED PRODUCT, THEREFORE, BOIL AND FREEZE PROTECTION ARE MEASURED IN THE SAME FASHION AS CONVENTIONAL COOLANTS. TO FULLY REALIZE ITS MANY ADVANTAGES, DEX-COOL(TM) MUST NEVER BE MIXED WITH CONVENTIONAL COOLANTS. It is particularly important to top-off new vehicles with DEX-COOL(TM) DEX-COOL(TM) forms a protective film on aluminum surfaces, however, if a vehicle with less than 3,000 miles is topped-off with conventional coolant, aluminum corrosion may occur. DEX-COOL(TM) CAN BECOME CONTAMINATED BY INADVERTENTLY TOPPING-OFF WITH CONVENTIONAL COOLANT, ADDING CONVENTIONAL COOLANT TO THE RADIATOR, OR EVEN IF FILL/DRAIN CONTAINERS ARE SHARED BETWEEN COOLANTS. If contamination occurs on a new vehicle (i.e. during vehicle prep), the cooling system must be immediately drained and refilled with DEX-COOL(TM) If contamination with conventional coolant occurs after the vehicle has been driven for at least 3,000 miles, no short-term problems will occur; however, the service change interval will be reduced from 5 years/100,000 miles to 2 years/30,000 miles. More information on DEX-COOL(TM) engine coolant service procedures can be found in the 1996 Service Manuals and a video tape which will be issued by STG. Vehicles which contain DEX-COOL(TM) can be identified by a special underhood label which states "USE DEX-COOL(TM) COOLANT ONLY. .. meeting Spec. 6277M". They may also be identified by the coolant's orange color and the information contained in the Owner's Manual. REGARDING COOLANT RECYCLING Engine coolant recycling is affected by DEX-COOL(TM) as follows. Used DEX-COOL(TM) can be mixed into your "used" conventional coolant storage vessel and the mixture recycled in the same manner as you are accustomed to. This recycled mixture of conventional and DEX-COOL(TM) coolant must be used as a 2 year/30,000 mile conventional coolant and should not be used in vehicles originally equipped with DEX-COOL(TM) When servicing vehicles originally equipped with DEX-COOL(TM), use only Goodwrench-DEX-COOL(TM) Additional research will be conducted to evaluate the feasibility of recycling DEX-COOL(TM) to DEX-COOL(TM) in the near future. Tires/Wheels - Low Tire/Leaking Cast Aluminum Wheels Wheels: All Technical Service Bulletins Tires/Wheels - Low Tire/Leaking Cast Aluminum Wheels TECHNICAL Bulletin No.: 05-03-10-003F Date: April 27, 2010 Subject: Low Tire Pressure, Leaking Cast Aluminum Wheels (Repair with Adhesive Sealant) Models: 2011 and Prior GM Passenger Cars and Light Duty Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X with Cast Aluminum Wheels Supercede: This bulletin is being revised to update the model years and the bulletin reference information. Please discard Corporate Bulletin Number 05-03-10-003E (Section 03 - Suspension). Condition Some customers may comment on a low tire pressure condition. Diagnosis of the low tire pressure condition indicates an air leak through the cast aluminum wheel. Cause Porosity in the cast aluminum wheel may be the cause. Notice This bulletin specifically addresses issues related to the wheel casting that may result in an air leak. For issues related to corrosion of the wheel in service, please refer to Corporate Bulletin Number 08-03-10-006C - Tire Slowly Goes Flat, Tire Air Loss, Low Tire Pressure Warning Light Illuminated, Aluminum Wheel Bead Seat Corrosion (Clean and Resurface Wheel Bead Seat). Correction 1. Remove the tire and wheel assembly from the vehicle. Refer to the appropriate service procedure in SI. 2. Locate the leaking area by inflating the tire to 276 kPa (40 psi) and dipping the tire/wheel assembly in a water bath, or use a spray bottle with soap and water to locate the specific leak location. Important - If the porosity leak is located in the bead area of the aluminum rim (where the tire meets the rim), the wheel should be replaced. - If two or more leaks are located on one wheel, the wheel should be replaced. 3. If air bubbles are observed, mark the location. - If the leak location is on the tire/rubber area, refer to Corporate Bulletin Number 04-03-10-001F Tire Puncture Repair Procedures for All Cars and Light Duty Trucks. - If the leak is located on the aluminum wheel area, continue with the next step. 4. Inscribe a mark on the tire at the valve stem in order to indicate the orientation of the tire to the wheel. 5. Dismount the tire from the wheel. Refer to Tire Mounting and Dismounting. 6. Remove the tire pressure sensor. Refer to Tire Pressure Sensor removal procedure in SI. 7. Scuff the INSIDE rim surface at the leak area with #80 grit paper and clean the area with general purpose cleaner, such as 3M(R) General Purpose Adhesive Cleaner, P/N 08984, or equivalent. 8. Apply a 3 mm (0.12 in) thick layer of Silicone - Adhesive/Sealant, P/N 12378478 (in Canada, use 88900041), or equivalent, to the leak area. 9. Allow for the adhesive/sealant to dry. Notice Caution must be used when mounting the tire so as not to damage the sealer. Damaging the repair area may result in an air leak. Page 2932 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3283 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3108 Manifold Absolute Pressure (MAP) Sensor: Locations Powertrain Control Module - PCM MAP Sensor The Manifold Absolute Pressure (MAP) Sensor is located on a bracket, mounted to the intake manifold, on the passenger side rear. Page 838 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Specifications Throttle Position Sensor: Specifications Idle (normal) ........................................................................................................................................ ....................................................... 0.45 to 0.95 volts (maximum) ........................................................................................................................................... .......................................................... 1.25 volts Wide Open Throttle ............................................................................................................................. ........................................................... 4.0 to 4.5 volts The Throttle position Sensor is not adjustable on this engine but should read below 1.25 volts at closed throttle and about 4.5 volts at wide open throttle. Page 3811 Engine Control Module: Specifications With 4L80-E Automatic Transmission PCM Connector Pin-Out Page 2609 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 414 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1153 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Electrical - MIL ON/DTC's Set By Various Control Modules Relay Module: Customer Interest Electrical - MIL ON/DTC's Set By Various Control Modules TECHNICAL Bulletin No.: 09-06-03-004D Date: December 08, 2010 Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion (Disconnect Affected Connector and Apply Dielectric Lubricant) Models: 2011 and Prior GM Passenger Cars and Trucks Attention: This repair can be applied to ANY electrical connection including, but not limited to: lighting, body electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the point where it prevents the full engagement of sealed connectors. A light coating on the terminal surfaces is sufficient to correct the condition. Supercede: This bulletin is being revised to update the Attention statement and add the 2011 model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System). Condition Some customers may comment on any of the following conditions: - An intermittent no crank/no start - Intermittent malfunction indicator lamp (MIL) illumination - Intermittent service lamp illumination - Intermittent service message(s) being displayed The technician may determine that he is unable to duplicate the intermittent condition. Cause This condition may be caused by a buildup of nonconductive insulating oxidized debris known as fretting corrosion, occurring between two electrical contact surfaces of the connection or connector. This may be caused by any of the following conditions: - Vibration - Thermal cycling - Poor connection/terminal retention - Micro motion - A connector, component or wiring harness not properly secured resulting in movement On low current signal circuits this condition may cause high resistance, resulting in intermittent connections. On high current power circuits this condition may cause permanent increases in the resistance and may cause a device to become inoperative. Representative List of Control Modules and Components The following is only a representative list of control modules and components that may be affected by this connection or connector condition and DOES NOT include every possible module or component for every vehicle. - Blower Control Module - Body Control Module (BCM) - Communication Interface Module (CIM) - Cooling Fan Control Module - Electronic Brake Control Module (EBCM) - Electronic Brake and Traction Control Module (EBTCM) - Electronic Suspension Control (ESC) Module - Engine Control Module (ECM) - Heating, Ventilation and Air Conditioning (HVAC) Control Module Page 3798 Data Link Connector (DLC) Pin Assignment Page 3684 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 1474 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1155 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 229 Fig.1-Symbols (Part 1 Of 3) Page 840 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 448 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 1241 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 857 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3292 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 191 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3409 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3757 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3124 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 920 Knock Sensor Circuit Page 2318 Lower Control Arm Replacement Procedure (K-Trucks with 8600 # GVW's and Below) Following the procedure given in section 3C of the service manual, replace the lower control arms with the new style lower control arms. It should be noted that the new lower control arms include a pressed in ball joint. Part numbers for the lower control arm front and rear bushings are also given below. Front Axle Seal Cover Installation Procedure Follow the instructions included in the seal cover service kits. Appropriate part numbers are shown below. Be sure to order the correct seal cover based on the GVW of the subject vehicle. Parts Information Parts are currently available from GMSPO. Warranty Information Important: Implementation of this bulletin by Canadian dealers requires prior DSM approval. Installation of seal cover service kits is an 'owner pay' service and as such requires prior owner approval. For vehicles repaired under warranty. Page 1957 Tire Requisition & Return Document Campaign Identification Label/Claim Info. Each vehicle corrected in accordance with the instructions outlined in this Product Campaign Bulletin will require a "Campaign Identification Label". Each label provides a space to include the campaign number and the five (5) digit dealer code of the dealer performing the campaign service. This information may be inserted with a typewriter or a ball point pen. Each "Campaign identification Label" is to be located on the radiator core support in an area which will be visible when the vehicle is brought in by the Page 1804 reservoir fluid level to full only after installing new brake pads and/or shoes. A full reservoir is indicated on translucent, snap cover reservoirs by a fluid level even with the top level of the view window imprinted into the side of the reservoir. On screw top models in black or translucent plastic, the full level is just below the bottom of the filler neck. Parts Information Part Number Description 12377967 Brake Fluid Parts are currently available from GMSPO. Disclaimer Page 976 1994 P TRUCK 3A-66 Specifications Temperature Vs Resistance Value Page 296 Page 295 Page 3879 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3325 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground I/P Fuse Block Fuse: Application and ID I/P Fuse Block I/P Fuse Block Page 1600 Frame Angle Measurement (Express / Savana Only) ........ Page 91 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 197 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1037 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3805 Engine Control Module: Technical Service Bulletins PCM - Replacement Component Text Deletion File in Section: 6E - Engine Fuel & Emission Bulletin No.: 41-65-33 Date: October, 1994 SERVICE MANUAL UPDATE Subject: Section 3A - Driveability, Emissions and Electrical Diagnosis - Text Deletion Models: 1994 Chevrolet and GMC Truck & T Models with 2.2L Gasoline Engine (VIN 4 - RPO LN2) or 4.3L Engine (VINs Z, W - RPOs LB4, L35) 1994-95 Chevrolet and GMC Truck C/K, M/L, G, P3, PG Models with 4.3L Engine (VIN Z - RPO LB4), 5.0L Engine (VIN H - RPO L03), 5.7L Engine VIN K - RPO L05) or 7.4L Engine (VIN N - RPO L19) 1994-95 Chevrolet and GMC Truck C/K, G, P3 Models with 6.5L Diesel Engine (VINs F, P, S RPOs L65, L49, L56) This bulletin contains revisions to the "Driveability, Emissions and Electrical Diagnostic" Service Manuals for the following pages: 1994 S/T Truck - 3A-5 1994-1995 G Van - 3A-4 1994-1995 C/K Truck - 3A-4 1994-1995 M/L Truck - 3A-4 1994-1995 PG/P3 Truck - 3A-4 1994-1995 C/K, G, P Truck - 3-17 and Supplement This Text is to be Deleted "The replacement PCM may be faulty - After the PCM is replaced, the system should be rechecked for proper operation. If the Diagnostic Chart again indicates that the PCM is the problem, substitute a known good PCM". Page 2366 Intake Manifold: Technical Service Bulletins Engine - Use of Wacker RTV Sealant for Intake Manifold File In Section: 6 - Engine Bulletin No.: 67-61-17A Date: August, 1996 Subject: Use of Wacker T-330 RTV Sealant (Pronounced Vaucker T) Models: 1990-96 Buick Road master, Estate Wagon 1990-96 Cadillac Fleetwood 1990-96 Chevrolet Camaro, Caprice, Corvette, Impala SS 1990-92 Oldsmobile Custom Cruiser 1990-96 Pontiac Firebird with 4.3L, 5.7L Engine (VINs W, P, 5, 8 - RPOs L99, L98, LT1, LT4) 1990-96 Chevrolet and GMC Light and Medium Duty Trucks with 4.3L, 5.0L, 5.7L, 6.0L, 7.0L, 7.4L Engines (VINs W, Z, E H, K, M, N, P, R - RPOs L35, LB4, L03, L05, LS0, LR0, L19, L30, L31) This bulletin is being revised to add further Chevrolet models. Please discard Corporate Bulletin Number 67-61-17 (Section 6 - Engine). When installing the intake manifold, use a 5 mm (1/4 in.) thick bead of Wacker T-330 RTV, P/N 12346192, on the front and rear sealing areas between Page 1335 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Locations Heater Hose Routing Page 3666 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 1395 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2194 12 through 14 in the "in-vehicle" service outlined above. 11. Reinstall the upper main bearing. 12. Reinstall the main cap and lower bearing; torque to 110 N.m (80 lb ft). 13. Repeat for each main bearing. 14. Reinstall oil pump and shield; torque to 88 N.m (65 lb ft). 15. Reinstall dipstick tube. 16. Reinstall oil pan. 17. Reinstall engine in vehicle. 18. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 19. Install fuel pump fuse, start engine, check for leaks or unusual noises. 20. Road test vehicle, check for leaks or unusual noises. Correction Category B: Valve Train Clatter, Tick or Click For 1992-94 vehicles equipped with a 4.3L V6 (LB4 VIN Z or L35 VIN W) engine see Corporate Bulletin 376006 for information on converting from net lash to adjustable lash and/or re-lashing the valves on an adjustable lash system. Investigation of "cold knock" is continuing. Updates will continue to be provided when available. Parts Information Check-Valve Filters Description Part Number V6, V8 (Four-Wheel Drive) FRAM PH3980 12555891 V8 (Two-Wheel Drive), Mark V8 PF1218 25160561 The FRAM PH3980 is to be used in place of the PF52. The PH3980 provides superior anti-drainback performance, a key factor in reducing cold knock. FRAM filters are to be procured locally until 08-15-95. After this date the filters may be ordered from GMSPO using the supplied part number. Orders placed to GMSPO prior to this date will not be placed on backorder. Bearings Description Part Number 0.001" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 10120992 0.001" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 10120994 0.002" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 12329758 0.002" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 12329792 Main bearing kits are currently available from GMSPO. All calibrations are currently available from GMSPO. Page 2845 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 507 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1737 EXAMPLE 2: The lower insert is stamped STD (standard) and the upper is stamped 0.0010". The undersize for a STD bearing is 0. Divide 0 by 2 to get 0. Divide 0.0010" by 2 to get 0.0005". Add 0 and 0.0005" together to calculate the bearing undersize, which is 0.0005" in this case. 13. Add the original bearing undersize calculated in step 12 to the clearance measured and written down in step 9. For example, if a clearance of 0.0030" was measured with plastigage in step 9 and the calculated bearing undersize from step 12 was 0.0005", the bearing clearance for that particular main journal is equal to 0.0030" plus 0.0005". The bearing clearance would be 0.0035" in this case. 14. Determine which of the combinations of two sizes of replacement bearings will produce the desired clearance. The two sizes available are 0.001" and 0.002". One insert of each size may be combined to produce an intermediate undersize of 0.0015". Subtract the replacement bearing size from the actual clearance to determine which bearing should be used. The bearing that should be used is the one which gives a clearance closer to 0.0008" than to 0.0028". The clearance must not be less than 0.0008". Using the example from step 11, the actual clearance is 0.0035". Subtracting 0.001" from 0.0035" will give a clearance of 0.0025", just barely within the required range. Subtracting 0.002" from 0.0035" will give a clearance of 0.0015". The 0.002" undersize bearing set would be the one to use in this case since it gives a clearance closer to 0.0008", but not less. 15. Install the replacement upper main bearing insert using tool J 8080. 16. Install the replacement lower main bearing insert in the main bearing cap. Lay a piece of plastigage across the width of the lower main bearing insert (same as step 5). 17. Repeat steps 7, 8 and 9. 18. Measuring the plastigage with the scale on the envelope, verify the clearance of the replacement bearings is within the range of 0.001" to 0.003". 19. Repeat steps 4 through 16 for each main bearing. 20. Thrust the crankshaft forward and backward several times to seat the thrust bearing. 21. Reinstall oil pump; torque to 88 N.m (65 lb ft). 22. Reinstall the oil pan and other hardware. 23. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 24. Install fuel pump fuse, start engine, check for leaks or unusual noises. 25. Road test vehicle, check for leaks or unusual noises. THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE OUT OF THE VEHICLE Recommended for K, S and T vehicles. 1. Remove the engine from the vehicle using the appropriate service manual procedure. 2. Mount the engine on an engine stand, flip the engine so the oil pan is facing up. 3. Remove the oil pan. 4. Remove the oil pump and shield. 5. Remove the dipstick tube. 6. Remove one (1) main bearing cap (must do one at a time). 7. Plasti-gage bearing. 8. If the bearing clearance is out of specification (clearance greater than 0.003 inches), remove upper main bearing from the block. 9. Check the size of the original bearing. 10. Determine what combination of new bearings are required to get the clearance in the acceptable range of 0.0008 inches to 0.0028 inches. See steps Page 3430 Fig.1-Symbols (Part 1 Of 3) Page 756 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 802 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3445 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1002 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3227 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1423 Neutral Safety Switch: Service and Repair 4L80-E PARK/NEUTRAL BACKUP SWITCH REPLACEMENT/ADJUSTMENT Remove - Apply parking brake. - Shift transmission to neutral. 1. Negative battery cable. 2. Transmission control lever to manual shaft nut. 3. Transmission control lever from manual shaft. Let shift cable and control lever drop out of the way. 4. Wiring harness connector from switch. 5. Switch to transmission bolts. 6. Switch from transmission. Slide switch from manual shaft. Install 1. Install Tool J41364-A to Park Neutral Back Up Switch. Be sure that the two detentes on the switch (where manual shaft is inserted) are lined up with the lower two tabs on tool. Rotate tool until upper locator pin on tool is lined up with locator on switch. 2. Switch to transmission. - Before sliding the switch on to the shaft, it may be necessary to lightly file the outer edge of the manual shaft to remove any burrs from the shaft. 3. Switch to transmission bolts. - Tighten Switch to transmission bolts to 27 Nm (20 lbs. ft.). 4. Remove Tool J-41364A from switch. 5. Wiring harness connectors to switch. 6. Transmission control lever to manual shaft. 7. Transmission control lever to manual shaft nut. - Tighten Control lever nut to 27 Nm (20 lbs. ft.). 8. Lower vehicle. 9. Negative battery cable. 10. Check switch for proper operation. Page 1438 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 2719 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3172 Oxygen Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical With Manual Transmission Engine Control Module: Specifications With Manual Transmission PCM Connector Pin-Out Locations Cargo Lamp Switch Wiring Page 1121 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 757 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 2707 Fig.1-Symbols (Part 1 Of 3) Diagram Information and Instructions Knock Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3192 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1751 1993 to 1995 L05 VIN K Install the appropriate check valve oil filter P/N 25160561 (PF1218 for two-wheel C-series and P/N 12555891 (FRAM PH3980) for four-wheel drive K-series). If the oil filter does not cure the condition, install the appropriate calibration from the table (calibrations are available for some 1993 and 1994 L05 applications). All calibrations are for light duty vehicles equipped with 4L60-E (M30) transmissions (no heavy duty emission/4L80-E calibrations are available). If a calibration is not offered or does not cure the short duration cold knock condition, install the appropriate main bearings as determined by the procedure. 1990-94 L19 VIN N Page 2368 Intake Manifold: Service and Repair Intake manifold tightening sequence 454 1. Disconnect battery ground cable, then drain cooling system. 2. Remove air cleaner. 3. Disconnect upper radiator and heater hoses at manifold and bypass hose at water pump. 4. Disconnect all electrical connectors and vacuum lines from TBI unit. Disconnect fuel lines from TBI unit. 5. Remove distributor. 6. Remove air conditioning compressor and front bracket, then position aside. 7. Remove rear air conditioning compressor bracket, then the right rear alternator bracket. 8. Remove emission sensors and bracket. 9. Remove intake manifold attaching bolts, then the intake manifold. 10. Reverse procedure to install, using new gaskets and seals. Tighten manifold bolts to specifications in sequence shown in Fig. 4. Page 1793 Heater Hose: Service and Repair Heater Outlet Hose Heater Hose Routing Quick Connect Heater Inlet Connector Remove or Disconnect 1. Engine coolant. 2. Hose clamps. 3. Outlet hose clip. 4. Outlet hose from heater core. 5. Outlet hose from radiator. Install or Connect 1. Outlet hose to radiator. 2. Outlet hose to heater core. 3. Outlet hose clip. 4. Hose clamps. 5. Engine coolant. - Check system for leaks. Page 3733 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Diagram Information and Instructions Cruise Control Switch: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3615 Fig.2-Symbols (Part 2 Of 3) Page 2822 Fig.2-Symbols (Part 2 Of 3) Page 2817 Vehicle Speed Sensor Buffer Page 188 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 536 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 241 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 778 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1257 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2955 Fig.2-Symbols (Part 2 Of 3) Power Window Switches Power Window Switch: Locations Power Window Switches Power Window Switches Page 3157 Oxygen Sensor: Technical Service Bulletins Oxygen Sensors - Silica Contamination Model Year: 1981 Bulletin No: 81-I-37 File In Group: 60 Number: 11 Date: Feb. 81 Subject: Silica Contamination of Oxygen Sensors and Gelation of Oil. Models Affected: All Oxygen sensor performance can deteriorate if certain RTV silicone gasket materials are used. Other RTV's when used with certain oils, may cause gelation of the oil. The degree of performance severity depends on the type of RTV and application of the engine involved. Therefore, when repairing engines where this item is involved, it is important to use either cork composition gaskets or RTV silicone gasket material approved for such use. GMS (General Motors Sealant) or equivalent material can be used. GMS is available through GMPD with the following part numbers: 1052366 3 oz. 1052434 10.14 oz. Page 2998 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 2033 *This product is currently available from 3M. To obtain information for your local retail location please call 3M at 1-888-364-3577. **This product is currently available from Meguiars (Canada). To obtain information for your local retail location please call Meguiars at 1-800-347-5700 or at www.meguiarscanada.com. ^ This product is currently available from Tri-Peek International. To obtain information for your local retail location please call Tri-Peek at 1-877-615-4272 or at www.tripeek.com. Disclaimer Diagram Information and Instructions Vehicle Speed Sensor/Transducer - Cruise Control: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3502 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 1238 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 2812 Engine Control Module: Specifications With 4L80-E Automatic Transmission PCM Connector Pin-Out Page 1958 customer for periodic servicing. When installing the Campaign Identification Label, be sure to install the clear protective covering. Additional Campaign Identification Labels can be obtained from VISPAC Incorporated by calling 1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when ordering. Apply the "Campaign Identification Label" only on a clean, dry surface. Submit a Product Campaign Claim with the information as shown. Refer to the General Motors Corporation Claims Processing Manual for details on Product Campaign Claim Submission. Owner Letter June, 1996 Dear Chevrolet Truck Customer: This notice is sent to you in accordance with the requirements of the National Traffic and Motor Vehicle Safety Act. REASON FOR THIS RECALL General Motors has decided that a defect which relates to motor vehicle safety exists in certain 1995-1996 G Vans 30 Series and C/K Crew Cab trucks equipped with General Ameri*550 AS LT225/75R16D tires. Some of these vehicles have bead damage to the tires which occurred during tire mounting. This damage to the tire reinforcing structure in the bead "toe" area would likely manifest itself as a bulge in the sidewall after the tire is inflated. The bulge may be noticeable when the tire is used in a single wheel position. But, if it is used in a dual rear wheel installation, the bulges on the tires would face each other and would not be noticeable. Typically, this condition would result in a slow air loss causing the tire to go flat. However, it is possible for the damage to result in a rapid air loss, which could cause injuries to anyone if they were handling the tire when this occurred. WHAT WE WILL DO To correct this condition, your Chevrolet dealer will demount each General tire and inspect it for bead damage. If bead damage is present, the tire will be replaced. This service will be performed for you at no charge. WHAT YOU SHOULD DO Please contact your Chevrolet dealer as soon as possible to arrange a service date and so the dealer may order the necessary parts for the repair. Instructions for making this correction have been sent to your dealer. The labor time necessary to perform this service correction is approximately 1 hour and 15 minutes to 3 hours and 45 minutes depending on the number of tires involved. Please ask your dealer if you wish to know how much additional time will be needed to schedule and process your vehicle. The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will assist in making the necessary correction in the shortest possible time. If you have sold or traded your vehicle, please let us know by completing the postage paid reply card and returning it to us. Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service date, and they do not remedy this condition on that date or within five (5) days, we recommend you contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020. Page 1392 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3039 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3929 Fig.1-Symbols (Part 1 Of 3) Page 799 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Electrical Specifications Oxygen Sensor: Electrical Specifications Closed Loop .......................................................................................................................................................... 100 mV (0.1 volt) to 0.999 mV (1.0 volt) Page 1193 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1409 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 1133 Fig.1-Symbols (Part 1 Of 3) Valve Clearance Specifications Valve Clearance: Specifications Valve Clearance Specifications Engine Liter/CID .................................................................................................................................. ........................................................... 7.4L/V8-454 All specifications given in inches. Stem Diameter Std. Intake ................................................................................................................................................... ...................................................... 0.3715-0.3722 Exhaust ................................................................ ...................................................................................................................................... 0.3715-0.3722 Maximum Tip Refinish ......................................................................................................................... ........................................................................ [03] Face Angle .......................................................... ....................................................................................................................................................... 45 deg. Margin [01] Intake ................................................................................................................................................... .................................................................. 0.0315 Exhaust ................................................................. .................................................................................................................................................. 0.0315 Valve Lash ........................................................................................................................................... ........................................................................... [06] [01] Minimum. [03] Grind only enough to provide true surface. After grinding valve stems, ensure sufficient clearance remains between rocker arm & valve spring cap or rotator. [06] Torque rocker arm bolt to 40 ft. lbs Page 3144 MAP Sensor Circuit CIRCUIT DESCRIPTION The Manifold Absolute Pressure (MAP) sensor measures the changes in the intake manifold pressure which result from engine load (intake manifold vacuum) and rpm changes; and converts these into a voltage output. The PCM sends a 5 volt reference voltage to the MAP sensor. As the manifold pressure changes, the output voltage of the sensor also changes. By monitoring the sensor output voltage, the PCM knows the manifold pressure. At lower pressure output voltage will be about 1 to 2 volts at idle. While at higher pressure or at Wide Open Throttle (WOT) output voltage will be about 4 to 4.8 volts. The MAP sensor is also used, under certain conditions, to measure barometric pressure, allowing the PCM to make adjustments for different altitudes. The PCM uses the MAP sensor to control fuel delivery and ignition timing. CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic chart. IMPORTANT: Be sure to use the same diagnostic test equipment for all measurements. 1. Checks MAP sensor output voltage to the PCM. This voltage, without engine running, represents a barometer reading to the PCM. ^ When comparing Tech 1 scan readings to a known good vehicle, it is important to compare vehicles that use a MAP sensor having the same color insert or having the same "Hot Stamped" number. Refer to figures in chart. 2. Applying 34 kPa (10" Hg) vacuum to the MAP sensor should cause the voltage to change. Subtract second reading from the first. Voltage value should be greater than 1.5 volts. Upon applying vacuum to the sensor, the change in voltage should be instantaneous. A slow voltage change indicates a faulty sensor. 3. Check vacuum hose to sensor for leaking or restriction. Be sure that no other vacuum devices are connected to the MAP hose. NOTE: Make sure electrical connector remains securely fastened. 4. Disconnect sensor from bracket and twist sensor by hand (only) to check for intermittent connection. Output changes greater than 0.1 volt indicate a bad connector or connection. If OK, replace sensor. Harness View Engine Specifications Intake Air Temperature Sensor: Specifications Torque Valve Torque Valve Induction Air Sensor 44 in.lb Page 1342 Knock Sensor Circuit CIRCUIT DESCRIPTION The Knock Sensor (KS) system consist of a knock sensor with one wire that goes directly to the PCM. There is a check performed by the PCM. The check consist of monitoring CKT 496 for a voltage that is more than 0.04 volt and less than 4.6 volts. If the voltage is either too high or too low for 16 or more seconds, DTC 43 will set. CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic chart. 1. The first test is to determine if the system is functioning at the present time. 2. Test two determines the state of the 5 volt reference voltage applied to the knock sensor circuit. DIAGNOSTIC AIDS The PCM applies 5 volts to CKT 496. A 3900 ohm resistor in the knock sensor reduces the voltage to about 2.5 volts. When knock occurs, the knock sensor produces a small AC voltage that rides on top of the 2.5 volts already applied. An AC voltage monitor, in the PCM, is able to read this signal as knock and incrementally retard spark. If the KS system checks OK, but detonation is the complaint, refer to Diagnosis By Symptom / Detonation, Spark Knock See: Powertrain Management/Computers and Control Systems/Testing and Inspection/Symptom Related Diagnostic Procedures/Detonation/ Spark Knock Page 816 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 741 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 517 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1222 Camshaft Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 911 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Locations Engine Page 3381 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Gauge Readings Are Inaccurate Oil Pressure Gauge: Testing and Inspection Gauge Readings Are Inaccurate 1. Remove lead from sensor, then connect tester J 33431-A or equivalent to sensor lead and ground. 2. If gauge responds accurately to tester, replace sensor. 3. If gauge does not respond accurately to tester, replace cluster. Page 2579 Fan Clutch: Description and Operation Fan Drive Clutch Assembly Variable Speed Fan W/Bi-Metallic Coiled Thermostatic Spring The fan drive clutch, Fig. 1, is a fluid coupling containing silicone oil. Fan speed is regulated by the torque-carrying capacity of the silicone oil. The more silicone oil in the coupling, the greater the fan speed, and the less silicone oil, the slower the fan speed. The type of fan drive clutch in use is a coiled bimetallic thermostatic spring, Fig. 2. The fan drive clutch uses a heat-sensitive, coiled bimetallic spring connected to an opening plate which regulates the flow of silicone oil into the coupling from a reserve chamber. The silicone oil is returned to the reserve chamber through a bleed hole when the valve is closed. This unit causes the fan speed to increase with a rise in temperature and to decrease as temperature decreases. Page 230 Fig.2-Symbols (Part 2 Of 3) Page 689 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Engine - Cold Knock, Replace Oil Filter/Bearings/PROM Crankshaft Main Bearing: Customer Interest Engine - Cold Knock, Replace Oil Filter/Bearings/PROM File In Section: 6 - Engine Bulletin No.: 37-61-05A Date: October, 1995 Subject: Cold Engine Knock (Replace Oil Filter/Bearings/PROM) Models: 1990-95 Chevrolet and GMC Truck C/K, R/V, S/T, M/L, G, P Models 1991-92 Oldsmobile Bravada with 4.3L (VIN Z - RPO LB4), 5.7L (VIN K - RPO L05), 7.4 (VIN N - RPO L19) Engine This bulletin is being revised to add the 1995 model year information. Please discard Corporate Bulletin Number 37-61-05 (Section 6 - Engine). Condition Some late model truck engines have been reported to exhibit "cold knock" on start up. "Cold Knock" usually occurs after the vehicle has been completely warmed up, then parked for 8 or more hours in ambient temperatures of 35° F or less. "Cold knock" can be separated into three distinct categories. 1. Short Duration - Harsh, deep metallic knock that usually lasts from 1 to 10 seconds. Generally classified as a bearing or rod knock. 2. Valve Train - Light clatter, tick or click that may last up to 1 minute. 3. Piston Slap - Metallic knock that occurs only under load. Piston slap may last as long as 5 minutes. Correction Category A: Short Duration Knock This matrix describes the repair for each affected model year and engine. Specific information for each affected model year and engine is supplied. Page 169 PCM Connector Pin-Out Page 3889 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2713 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3383 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Locations Power Door Lock Relay Description and Operation Coolant Level Indicator Lamp: Description and Operation This system uses a sensor mounted on the radiator and an indicator light mounted in the instrument panel to warn the driver if coolant level is too low. This light is wired in series with the ignition switch, ECM and the sensor. When the ignition switch is turned to the crank position, the circuit is energized and the indicator light will illuminate. When the ignition switch is turned to the ON position and coolant level is sufficient, the sensor will indicate this to the ECM and the light will turn off. Engine - Drive Belt Misalignment Diagnostics Drive Belt: Technical Service Bulletins Engine - Drive Belt Misalignment Diagnostics INFORMATION Bulletin No.: 08-06-01-008A Date: July 27, 2009 Subject: Diagnosing Accessory Drive Belt / Serpentine Belt Noise and Availability and Use of Kent-Moore EN-49228 Laser Alignment Tool - Drive Belt Models: 2010 and Prior GM Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3 Vehicles 2009 and Prior Saab 9-7X Supercede: This bulletin is being revised to add a model year and update the Tool Information. Please discard Corporate Bulletin Number 08-06-01-008 (Section 06 - Engine). Background Several aftermarket companies offer laser alignment tools for accessory drive systems that can be very helpful in eliminating drive belt noise as a result of misaligned pulleys. Typically pricing ranges from $160 - $200. EN-49228 Laser Alignment Tool - Drive Belt The GM Tool program has now made available a competitive, simple to use and time-saving laser tool to assist in achieving precise alignment of the drive belt pulleys. This optional tool removes the guesswork from proper pulley alignment and may serve to reduce comebacks from: - Drive Belt Noise - Accelerated Drive Belt Wear - Drive Belt Slippage Instructions The instructions below are specific only to the truck Gen IV V-8 family of engines. These instructions are only for illustrative purposes to show how the tool may be used. Universal instructions are included in the box with the Laser Alignment Tool - Drive Belt. Caution - Do not look directly into the beam projected from the laser. - Use caution when shining the laser on highly polished or reflective surfaces. Laser safety glasses help reduce laser beam glare in many circumstances. - Always use laser safety glasses when using the laser. Laser safety glasses are not designed to protect eyes from direct laser exposure. 1. Observe and mark the serpentine belt orientation. Specifications Fluid - Transfer Case: Specifications Transfer Case ...................................................................................................................................... .................................................................. Dexron III Page 1755 Warranty Information Crankshaft Rotation Timing Marks and Indicators: Locations Crankshaft Rotation Crankshaft Rotation (Typical Crankshaft Pulley) Crankshaft rotation is clockwise when viewed from in front of the crankshaft pulley as shown in the generic image. Diagram Information and Instructions Coolant Temperature Sensor/Switch (For Computer): Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 2475 Distributor: Description and Operation Distributor OPERATION The distributor is driven by the camshaft and mounts to the rear of the engine, it does not contain centrifugal advance weights, springs, or a vacuum advance unit. The distributor has an internal magnetic pickup assembly that contains a permanent magnet, a pole piece with internal teeth, and a pickup coil. When the rotating teeth of the timer core line up with the teeth of the pole piece, voltage is induced in the pickup coil. This voltage signals the Ignition Control Module (ICM) to trigger the primary ignition circuit. Current flow in the primary circuit is interrupted and up to 35,000 volts is induced in the ignition coil secondary winding. This high voltage is directed through the secondary ignition circuit to fire the spark plugs. No periodic lubrication is required. Engine oil lubricates the lower bushing. The upper bushing is prelubricated and sealed. Page 798 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3786 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1979 ^ Always inspect and adjust the pressure when the tires are cold. ^ Vehicles that have different pressures for the front and the rear need to be adjusted after tire rotation. Improper tire inflation may result in any or all of the following conditions: ^ Premature tire wear ^ Harsh ride ^ Excessive road noise ^ Poor handling ^ Reduced fuel economy ^ Low Tire Pressure Monitor (TPM) Light ON ^ Low Tire Pressure Message on the Drivers Information Center (DIC) Disclaimer Page 2583 Fan Clutch: Testing and Inspection Fan Clutch Noise Fan clutch noise can sometimes be noticed when clutch is engaged for maximum cooling. Clutch noise is also noticeable within the first few minutes after starting engine while clutch is redistributing the silicone fluid back to its normal, disengaged operating condition after settling for long periods of time (overnight). However, continuous fan noise or an excessive roar indicates the clutch assembly is locked-up due to internal failure. This condition can be checked by attempting to manually rotate fan. If fan cannot be rotated manually or there is a rough, abrasive feel as fan is rotated, the clutch should be replaced. Page 1230 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3661 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3782 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 92 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 2840 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 1041 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point DTC 45 (Rich Exhaust) Diagnostic Chart Revision Oxygen Sensor: Technical Service Bulletins DTC 45 (Rich Exhaust) Diagnostic Chart Revision File In Section: 6E - Engine Fuel & Emission Bulletin No.: 41-65-28 Date: October, 1994 SUBJECT: Section 3A - DTC 45 Rich Exhaust - Will Set When (Value Change) MODELS: 1994-95 Chevrolet and GMC Truck C/K, P Models, G Vans with 5.0L Engine (VIN H RPO LO3) 5.7L Engine (VIN K - RP0 LOS) - for 1994 under 8500 GVW 7.4L Engine (VIN N - RPO L19) This bulletin contains revisions to DTC 45 chart pages in the 1994-1995 G, C/K, P Truck "Driveability, Emissions and Electrical Diagnosis" manual as follows: Page 510 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3082 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1273 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3418 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2603 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3085 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3440 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3936 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 2731 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3455 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 1223 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 1734 condition, install the appropriate main bearings as determined by the following procedure. Calibration Information - 1992-93 LB4 VIN Z The revised PROMs reduce spark advance after the engine is started. The reduction in spark lowers the cylinder pressure and eliminates the knock. The revised PROMs will NOT eliminate a piston slap (Category C) or valve train noise (Category B) concern. The base cold knock PROM contains the previously released calibration updates. For 1992 LB4, the previous field release is included for torque converter clutch (TCC) lock up (see Bulletin 137107 - Chevrolet 92-75-7A; GMC Truck 92-7A-40; Oldsmobile 92-T-34; Canada 9274L60100) for automatic transmissions, or neutral gear rattle for manual transmissions (see Bulletin 267201R - Chevrolet 92-187B-7B; GMC Truck 92-7B-149A; Canada 93-7B-105). If a vehicle has had a detonation fix PROM installed previously, select the combined detonation and cold knock fix PROM for the application. See Bulletin 376508 for more information on field fix PROM for the application and detonation. Important: Use of a detonation fix PROM in a non-detonating vehicle may result in degraded driveability. GMSPO currently stocks three (3) PROMs for each light duty 1992 model year LB4 application. Base Cold Knock Fix Combination Cold Knock and Detonation Fix GMSPO Service Parts Assistance Center (SPAC 1-800-433-6961) will have information available on each PROM part number. Select the PROM from the table. Old Broadcast Code (Old B/C Code) and Scan I.D. information has been supplied to help installed previously. Use a TECH-1 to determine the Scan I.D. of the PROM in the vehicle or remove the PROM and read the Broadcast Code (B/C Code). If the B/C Code/Scan I.D. can be found in the first table, a detonation fix has not been installed. PROMs are currently available GMSPO. 1990-95 L05 VIN K Description and Operation A/C Signal: Description and Operation A/C Circuit PURPOSE: This signal indicates that the A/C control switch is turned "ON" and the pressure switch is closed. The control module uses this signal to adjust the idle speed. Page 873 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3575 Page 960 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 2937 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1118 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 179 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1671 Distributor: Specifications Distributor Hold Down Bolt .................................................................................................................. ................................................... 27 Nm (20 lbs. ft.) Description and Operation Temperature Warning Lamp/Indicator: Description and Operation A bi-metal temperature switch located in the cylinder head controls the operation of a temperature indicator light. If the engine cooling system is not functioning properly and/or coolant temperature exceeds a predetermined value, the warning light will illuminate. Page 551 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3051 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 531 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 456 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3022 Coolant Temperature Sensor/Switch (For Computer): Description and Operation Engine Coolant Temperature (ECT) Sensor PURPOSE The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40° C (-40° F) while high temperature causes low resistance (70 ohms at 130° C (266° F). OPERATION The control module supplies a 5 volt signal to the ECT sensor through a resistor in the control module and measures the voltage. The voltage will be high when the engine is cold, and low when the engine is hot. Engine coolant temperature affects most systems controlled by the control module. Page 1954 address data furnished will enable dealers to follow up with customers involved in this campaign. Any dealer not receiving a computer listing with the campaign bulletin has no involved vehicles currently assigned. These dealer listings may contain customer names and addresses obtained from State Motor Vehicle Registration Records. The use of such motor vehicle registration data for any other purpose is a violation of law in several states. Accordingly, you are urged to limit the use of this listing to the follow up necessary to complete this campaign. Parts/Customer Information Page 1055 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1399 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3951 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 121 Blower Motor Control Module, Idle Air Control Valve Page 3673 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3637 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1548 This relay incorporates a 5 second delay for the front axle to engage in order to allow the transfer case synchronizer to energize. For 88-93 vehicles, if the axle has to be replaced, use jumper harness P/N 15313272. CKT 1695 (BLK/WHT) fits into cavity A of the fast actuator. The circuit includes the cable seal and the terminal pin. This circuit plugs into the 5-pin axle actuator connector. 11. Do the following steps in order to install jumper harness P/N 15313272: a. Locate the axle actuator 5-pin connector on the service actuator wiring harness and remove the TPA. b. Remove and discard the cavity plug from cavity A. c. Install CKT 1695 lead (BLK/WHT) from the jumper harness that has the cable seal and terminal into axle actuator connector cavity A. d. Reinstall the TPA on the 5-pin connector. e. Install the service actuator harness 5-pin connector into the axle actuator. f. Connect jumper harness 2x2 connector into the existing vehicle 4WD mating connector. g. Strap the jumper harness and the service harness to the tab on the axle tube. Page 924 Knock Sensor: Service and Repair REMOVE OR DISCONNECT 1. Negative battery cable. 2. Drain cooling system. NOTE: On knock sensors which are mounted in the end of the cylinder head draining the cooling system will not be necessary. 3. Wiring harness connector from knock sensor. 4. Knock sensor from cylinder head or block. INSTALL OR CONNECT 1. Knock sensor into cylinder head or block. Apply water base caulk to sensor threads. Do not use silicon tape as this will insulate sensor from engine block. Tighten to 19 Nm (14 lb. ft.). 2. Wiring harness connector to the knock sensor. 3. Negative battery cable. 4. Refill cooling system if required. Page 2878 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 2847 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3837 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Door Switch - Dome Light Stays On/Dead Battery/No Start Door Switch: All Technical Service Bulletins Door Switch - Dome Light Stays On/Dead Battery/No Start File In Section: 8 - Chassis/Body Electrical Bulletin No.: 56-82-05 Date: September, 1995 Subject: Dome Lamp Stays On, Dead Battery, No Start (Shim Door Trim Panel Push Nail) Models: 1995 Chevrolet and GMC Truck C/K Models 1995 Topkick/Kodiak Models Condition Dome lamp stays on, with doors closed and headlight rotary wheel in the off position. Cause Dome lamp switch plunger is not pushed in far enough. There is too large a gap between the dome lamp switch plunger and the door panel convex push nail. Correction Shim out door panel push nail with color keyed shims available through GMSPO. Service Procedure Page 1229 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 818 Coolant Temperature Sensor/Switch (For Computer): Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Diagram Information and Instructions Crankshaft Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3867 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3895 Idle Air Control Valve: Description and Operation IAC Valve OPERATION: All engine idle speeds are controlled by the control module through the Idle Air Control (IAC) valve mounted on the throttle body. The control module sends voltage pulses to the IAC motor windings causing the IAC motor shaft and pintle to move in and out a given distance (number of steps) for each pulse, (called counts). This movement controls airflow around the throttle plate, which in turn controls engine idle speed, either cold or hot. IAC pintle position counts can be seen using a "Scan" tool. 0 counts correspond to a fully closed passage, while 140 counts or more (depending on application) corresponds to full airflow through the throttle body bypassing the throttle blade. ^ Actual or "controlled" idle speed is obtained by the control module positioning the IAC valve pintle. Resulting idle speed is generated from the total idle air flow (IAC/passage + PCV + throttle valve + vacuum leaks). ^ Controlled idle speed is always specified for normal operating conditions. Normal operating condition is engine coolant temperature in operating range, the A/C is "OFF," manual transmission is in neutral or automatic transmission in drive with proper park/neutral position. A high or low engine coolant temperature, or A/C clutch engagement may signal the control module to change the IAC counts. ^ The minium idle speed is set at the factory with a stop screw. This setting allows enough air flow by the throttle valves to cause the IAC valve pintle to be positioned a calibrated number of steps (counts) from the seat during normal controlled idle operation. ^ The IAC counts will be higher than normal on an engine with less than 500 miles, or an engine operating at high altitude or an engine with an accessory load such as the alternator, A/C, power steering or hydra-boost brakes activated. Page 2018 of vibration is normally felt more in the "seat of the pants" than the steering wheel. 5. Next, record the Hertz (Hz) reading as displayed by the EVA onto the tire data worksheet found at the end of this bulletin. This should be done after a tire break-in period of at least 16 km (10 mi) at 72 km/h (45 mph) or greater, in order to eliminate any possible tire flat-spotting. This reading confirms what the vehicle vibration frequency is prior to vehicle service and documents the amount of improvement occurring as the result of the various steps taken to repair. Completing the Steering Wheel Shake Worksheet below is required. A copy of the completed worksheet must be saved with the R.O. and a copy included with any parts returned to the Warranty Parts Center for analysis. A reading of 35 to 50 Hz typically indicates a first order propshaft vibration. If this is the situation, refer to Corporate Bulletin Number 08-07-30-044D. Generally, a reading between 10 and 20 Hz indicates a tire/wheel vibration and if this is the reading obtained, continue using this bulletin. If the tire 1st order vibration goes away and stays away during this evaluation, the cause is likely tire flat-spotting. Tire flat-spotting vibration may come and go at any speed over 72 km/h (45 mph) during the first 10 minutes of operation, if vibration continues after 10 minutes of driving at speeds greater than 72 km/h (45 mph), tire flat-spotting can be ruled out as the cause for vibration. 6. If flat-spotting is the cause, provide the explanation that this has occurred due to the vehicle being parked for long periods of time and that the nature of the tire is to take a set. Refer to Corporate Bulletin Number 03-03-10-007E: Information on Tire/Wheel Characteristics (Vibration, Balance, Shake, Flat Spotting) of GM Original Equipment Tires. 7. If the road test indicates a shake/vibration exists, check the imbalance of each tire/wheel assembly on a known, calibrated, off-car dynamic balancer.Make sure the mounting surface of the wheel and the surface of the balancer are absolutely clean and free of debris. Be sure to chose the proper cone/collet for the wheel, and always use the pilot bore for centering. Never center the wheel using the hub-cap bore since it is not a precision machined surface. If any assembly calls for more than 1/4 ounce on either rim flange, remove all balance weights and rebalance to as close to zero as possible. If you can see the vibration (along with feeling it) in the steering wheel (driving straight without your hands on the wheel), it is very likely to be a tire/wheel first order (one pulse per revolution) disturbance. First order disturbances can be caused by imbalance as well as non-uniformities in tires, wheels or hubs. This first order frequency is too low for a human to hear, but if the amplitude is high enough, it can be seen. If a vibration or shake still exists after balancing, any out of round conditions, of the wheel, and force variation conditions of the tire, must be addressed. Equipment such as the Hunter GSP9700 can address both (it is also a wheel balancer). Tire radial force vibration (RFV) can be defined as the amount of stiffness variation the tire will produce in one revolution under a constant load. Radial force variation is what the vehicle feels because the load (weight) of the vehicle is always on the tires. Although free runout of tires (not under load) is not always a good indicator of a smooth ride, it is critical that total tire/wheel assembly runout be within specification. Equipment such as the Hunter GSP9700 loads the tire, similar to on the vehicle, and measures radial force variation of the tire/wheel assembly. Note that the wheel is affecting the tire's RFV measurement at this point. To isolate the wheel, its runout must be measured. This can be easily done on the Hunter, without the need to set up dial indicators. If the wheel meets the runout specification, the tire's RFV can then be addressed. After measuring the tire/wheel assembly under load, and the wheel alone, the machine then calculates (predicts) the radial force variation of the tire. However, because this is a prediction that can include mounting inaccuracies, and the load wheel is much smaller in diameter than used in tire production, this type of service equipment should NOT be used to audit new tires. Rather, it should be used as a service diagnostic tool to minimize radial force variation of the tire/wheel assembly. Equipment such as the Hunter GSP9700 does an excellent job of measuring wheel runout, and of finding the low point of the wheel (for runout) and the high point of the tire (for radial force variation). This allows the tire to be matched mounted to the wheel for lowest tire/wheel assembly force variation. The machine will simplify this process into easy steps. The following assembly radial force variation numbers should be used as a guide: When measuring RFV and match mounting tires perform the following steps. Measuring Wheel Runout and Assembly Radial Force Variation Important The completed worksheet at the end of this bulletin must be attached to the hard copy of the repair order. - Measure radial force variation and radial runout. - If a road force/balancing machine is used, record the radial force variation (RFV) on the worksheet at the end of this bulletin. It may be of benefit to have the lowest RFV assembly to the front left corner. If the machine is not available and the EVA data suggests there is an issue, swap the tire and wheel assemblies from the front to the back. Re-check on the EVA and if the problem still exists, test another vehicle to find tires that do not exhibit the same frequency and swap those tires onto the subject vehicle. - If a runout/balancing machine is used, record the radial runout of the tire/wheel assemblies on the worksheet at the end of this bulletin. If one or more of the tire/wheel assemblies are more than.040 in (1.02 mm), match mount the tire to the wheel to get below.040 in (1.02 mm). For sensitive customers, readings of 0.030 inch (0.76 mm) or less are preferable, it may also be of benefit to have the lowest runout assembly to the front left corner. If the machine is not available and the EVA data suggests there is an issue, swap the tire and wheel assemblies from the front to the back. Re-check on the EVA and if the problem still exists, test another vehicle to find tires that do not exhibit the same frequency and swap those tires Page 309 Page 2412 Idle Speed: Specifications Controlled Idle Speed Transmission Gear Idle Speed IAC Counts [1] OPEN/CLOSED Loop [2] Manual N 750 +/- 25 5-30 CL Automatic D 675 +/- 25 5-30 CL [1] On manual transmission vehicles the SCAN tool will display RDL in Neutral. Add 2 counts for engines with less than 500 miles. Add 2 counts for every 1000 ft. above sea level. [2] Let engine idle until proper fuel control status is reached (OPEN/CLOSED loop). Page 930 Manifold Absolute Pressure (MAP) Sensor: Locations Powertrain Control Module - PCM MAP Sensor The Manifold Absolute Pressure (MAP) Sensor is located on a bracket, mounted to the intake manifold, on the passenger side rear. Page 3945 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1485 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 391 Coolant Temperature Sensor/Switch (For Computer): Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 2961 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 2964 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3509 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3659 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1454 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 120 Heater And A/C Control Select SW (C2), Stop Lamp & TCC Switch Jumper, Aux Fan Control SW Page 1132 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2192 Install a check valve oil filter; no other recommended actions at this time. Important: The previous actions are only applicable to short duration cold knock. These actions will not eliminate a knock occurring under load or a knock lasting for more than 10 seconds. Two main bearing procedures are recommended: 1. For main bearing replacement with the engine IN the vehicle: C, G, P, M and L vehicles 2. For main bearing replacement with the engine OUT OF the vehicle: K, S and T THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE IN THE VEHICLE Recommended for C, G, P, M and L vehicles. Important: A OEM training video has been produced for in-vehicle main bearing replacement procedure. One copy of the video will be sent to each dealer. If the video has not been received, contact XPRESS 1 Distribution Center at 1-800-783-3034. Main Bearing Clearance Determination and Installation Procedure 1. REMOVE THE SERPENTINE BELT, dipstick, dipstick tube and disconnect the negative battery cable. 2. Raise the vehicle and remove (or set aside) any parts restricting access to the oil pan bolts (i.e., starter motor, oil cooler lines, oil filter adapter, flywheel inspection cover). 3. Remove the oil pan, oil pump, and shield. 4. Remove # 5 (flange) bearing cap. Wipe the oil from the crankshaft journal and the lower main bearing insert. 5. Place a screw jack under an accessible part of the crankshaft, carefully apply pressure to the crankshaft to force it solidly against the top bearing insert. The reason for this is to remove any clearance between the top bearing insert and the crankshaft. If this step is not performed, a smaller than actual clearance will be measured. Important: This should be done as close as possible to the bearing being measured. This step is only required for on-vehicle service where the engine cannot be turned upside down as on an engine stand. 6. Place a piece of plastigage across the width of the lower bearing insert (parallel to the centerline of the crankshaft). 7. Reinstall # 5 main bearing cap. Torque to 110 N.m (80 lb ft). Do not allow crankshaft to turn. 8. Carefully remove the # 5 main bearing cap and bearing insert. The flattened plastigage will adhere to either the bearing insert or the crank journal. Do not remove the plastigage from the insert or journal. 9. On the edge of the plastigage envelope, there is a graduated scale. Without removing the flattened plastigage, measure its width at the widest point using the graduated scale on the plastigage envelope. 10. The desired main bearing clearance is 0.0008" - 0.0028". If the clearance measured with the plastigage is greater than 0.0028", write down the clearance. Next, read the back of the bearing insert to determine what size bearing was originally installed (usual STD, 0.0006", 0.0010" or 0.0012"). The size stamped on the bearing is the effective undersize when both inserts are installed. For example, a 0.0006" undersize bearing set consists of two (2) 0.0003" thicker bearing inserts, both stamped 0.0006". 11. Remove the top bearing insert using tool J 8080 and read the back to determine what size upper bearing insert was originally installed. The top insert may be different size than the bottom. 12. Calculate the original bearing undersize by dividing the size on each insert by 2, then add the values together. EXAMPLE 1: The lower insert is stamped 0.0006" and the upper is stamped 0.0010". Divide 0.0006" by two to get 0.0003". Divide 0.0010" by 2 to get 0.0005". Add 0.0003" and 0.0005" together to calculate the bearing undersize, which is 0.0008" in this case. Page 3001 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 524 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3764 Data Link Connector (DLC) Page 3616 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3363 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 2246 Page 781 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3276 Fig.2-Symbols (Part 2 Of 3) Page 1323 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 2923 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1815 coolant system integrity and will no longer be considered a 5 yr/150,000 mile (240,000 km) coolant. Coolant Removal Services/Recycling The tables include all coolant recycling processes currently approved by GM. Also included is a primary phone number and demographic information. Used DEX-COOL(R) can be combined with used conventional coolant (green) for recycling. Depending on the recycling service and/or equipment, it is then designated as a conventional 2 yr/30,000 mile (50,000 km) coolant or DEX-COOL(R) 5 yr/150,000 mile (240,000 km) coolant. Recycled coolants as designated in this bulletin may be used during the vehicle(s) warranty period. DEX-COOL(R) Recycling The DEX-COOL(R) recycling service listed in Table 2 has been approved for recycling waste engine coolants (DEX-COOL) or conventional) to DEX-COOL(R) with 5 yr/150,000 mile (240,000 km) usability. Recycling Fluid Technologies is the only licensed provider of Recycled DEX-COOL(R) meeting GM6277M specifications and utilizes GM approved inhibitor packages. This is currently a limited program being monitored by GM Service Operations which will be expanded as demand increases. Conventional (Green) Recycling Page 674 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1178 Fig.1-Symbols (Part 1 Of 3) Page 1484 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 1892 Fig. 10 Combination Valve Bleeding Tool Installation 1. Fill the pressure tank at least 2/3 full of brake fluid. Bleeder must be bled each time fluid is added. 2. Charge pressure bleeder to 20-25 psi. 3. Use tool No. J 39177, or equivalent, to depress and hold valve stem on combination valve, Fig. 10. 4. Install master cylinder adapter tool required for type of reservoir, then install bleeder hose to adapter 5. Bleed each wheel in the following sequence: a. Right rear. b. Left rear. c. Right front. d. Left front. 6. Open bleeder tank valve. 7. Attach a hose to caliper bleeder valve and immerse the opposite end of the hose into a suitable, clean, container, partially filled with clean brake fluid. 8. Open bleeder valve at least 3/4 turn and allow fluid to flow until no air is seen in fluid, then close valve. 9. Repeat procedure at each wheel. 10. Check brakes for "sponginess. Repeat bleeding procedure if necessary. 11. Remove pressure bleeder, adaptors, and tools, then fill reservoir to proper level. Page 760 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 3695 Fig.2-Symbols (Part 2 Of 3) Page 3698 Coolant Temperature Sensor/Switch (For Computer): Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 189 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3776 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 887 Knock Sensor Page 3168 Fig.1-Symbols (Part 1 Of 3) Page 1416 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1781 12. Using template (Figure 4), mark cutting lines on the upper evaporator case using a china marker or equivalent. Do not remove the locating tabs from the templates, they are needed to position the cut area for the access doors (Figure 1). Page 1159 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 518 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3433 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1278 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3619 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 670 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3623 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1417 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3195 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3711 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3703 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3450 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3795 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3229 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 362 19. Pull back access door on the upper evaporator case carefully to prevent breaking the case (Figure 1). Align the TXV capillary against the evaporator outlet tube being sure not to damage the capillary line. Place the first holding clamp so it is located 1/4" or less below the crimp in the capillary tube (Figure 3). Install the second clamp 1/4" or less below the first clamp. Be sure the clamps are fully seated on the tube and that the capillary is retained in the formed seat of each clamp (Figure 3, Section 1-1). Notice: After all components are installed, evacuate and charge the A/C system. Leak test all joints that were opened. 20. Using a heat gun to soften the plastic case, close both access doors and align the edges of the plastic. Using a soldering gun, melt both edges of the case together along the full length of the cuts, as smoothly as possible. 21. Cover the soldered closures with duct tape to prevent air leakage. 22. Reinstall the right side trim panel, the D-pillar trim, the C-pillar trim, the C-pillar seat belt retainer and the rear bench seat. Page 3293 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 742 Fig.1-Symbols (Part 1 Of 3) Page 3839 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Component Locations Four Wheel Drive Selector Relay: Component Locations TRANSFER CASE RELAY 4WD Relay (Diesel Engine Shown, Gas is Similar) The Transfer Case Relay is located in the RH rear of engine compartment, near center of cowl. Page 330 Harness Connector Faces Page 489 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Engine, A/T - Shift/Driveability Concerns/MIL ON Air Filter Element: Customer Interest Engine, A/T - Shift/Driveability Concerns/MIL ON Bulletin No.: 04-07-30-013B Date: February 01, 2007 INFORMATION Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007 HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X Supercede: This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 04-07-30-013A (Section 07 - Transmission/Transaxle). The use of an excessively/over-oiled aftermarket, reusable air filter may result in: Service Engine Soon (SES) light on Transmission shift concerns, slipping and damaged clutch(es) or band(s) Engine driveability concerns, poor acceleration from a stop, limited engine RPM range The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur. When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared to a like vehicle with an OEM air box and filter under the same driving conditions to verify the concern. The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty. If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and the air induction hose for contamination of oil prior to making warranty repairs. Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not considered to be warrantable repair items. Page 1203 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 3262 HD 5-Speed Manual Transmission W/4WD Page 1458 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 2973 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2977 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Locations Forward Lamps Harness, RH Side Page 3876 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 1088 5-Speed Manual Transmission VSS 4WD Or AWD Front Wheel Alignment Alignment: Service and Repair Front Wheel Alignment Front Caster and Camber Adjustment Vehicle Ride Height Location & Specifications Page 3384 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 1087 HD Electronic 4-Speed Automatic Overdrive Transmission HD 5-Speed Manual Transmission Technician Safety Information Fan Blade: Technician Safety Information WARNING: Do not operate engine until fan has first been inspected for cracks and/or separations. If a fan blade is found to be bent or damaged in any way, do not attempt to repair or reuse damaged part. Proper balance is essential in fan assembly operation. Balance cannot be assured once a fan assembly has been found to be bent or damaged and failure may occur during operation, creating an extremely dangerous condition. Always replace damaged fan assembly. Engine - Cold Knock, Replace Oil Filter/Bearings/PROM Oil Filter: Customer Interest Engine - Cold Knock, Replace Oil Filter/Bearings/PROM File In Section: 6 - Engine Bulletin No.: 37-61-05A Date: October, 1995 Subject: Cold Engine Knock (Replace Oil Filter/Bearings/PROM) Models: 1990-95 Chevrolet and GMC Truck C/K, R/V, S/T, M/L, G, P Models 1991-92 Oldsmobile Bravada with 4.3L (VIN Z - RPO LB4), 5.7L (VIN K - RPO L05), 7.4 (VIN N - RPO L19) Engine This bulletin is being revised to add the 1995 model year information. Please discard Corporate Bulletin Number 37-61-05 (Section 6 - Engine). Condition Some late model truck engines have been reported to exhibit "cold knock" on start up. "Cold Knock" usually occurs after the vehicle has been completely warmed up, then parked for 8 or more hours in ambient temperatures of 35° F or less. "Cold knock" can be separated into three distinct categories. 1. Short Duration - Harsh, deep metallic knock that usually lasts from 1 to 10 seconds. Generally classified as a bearing or rod knock. 2. Valve Train - Light clatter, tick or click that may last up to 1 minute. 3. Piston Slap - Metallic knock that occurs only under load. Piston slap may last as long as 5 minutes. Correction Category A: Short Duration Knock This matrix describes the repair for each affected model year and engine. Specific information for each affected model year and engine is supplied. Initial Inspection and Diagnostic Overview Serial Data: Initial Inspection and Diagnostic Overview 1.Check for proper connections of Scan Tool to Data Link Connector (DLC). 2. Check for loose or missing terminals at DLC. 3. If all components are not accessible with a Scan Tool, then check for an open in TAN (800) wire between S227 and DLC terminal "M". 4. If a single component is not accessible with a Scan Tool, then check for an open in TAN (800) wire between S227 and affected component. ^ Check for a broken (or partially broken) wire inside of the insulation which could cause system malfunction but prove "GOOD" in a continuity/voltage check with a system disconnected. These circuits may he intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage drop with the system operational (under load). ^ Check for proper installation of aftermarket electronic equipment which may affect the integrity of other system (Refer "Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids Page 3071 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 2996 Coolant Temperature Sensor/Switch (For Computer): Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3506 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 437 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3404 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3121 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 176 Vehicle Speed Sensor Buffer Page 3959 Knock Sensor: Description and Operation PURPOSE: The Knock Sensor (KS) is used to detect engine detonation (ping). OPERATION A 5 volt reference is applied to the knock sensor which has an internal resistance of about 3900 ohms. This resistance will lower the applied voltage to about half or 2.5 volts. When a knock is present, a small AC voltage is produced by the knock sensor and transmitted to the control module riding on top of the already existing 2.5 volts. An AC voltage monitor inside the control module will detect the knock and trigger the control module to start retarding the spark incrementally. A control module (ECM or PCM) is used in conjunction with one or two knock sensors to control detonation. A KS module will be found on ECM applications. On PCM application no KS module will be found as it is internal to the control module. Page 545 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 2894 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 530 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1316 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 2925 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3414 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 3738 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 955 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 196 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3456 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 2756 Temperature Warning Lamp/Indicator: Testing and Inspection If the light is not lit when the engine is being cranked, check for a burned out bulb, an open in the light circuit, or a defective ignition switch. If the light is lit when the engine is running, check the wiring between light and switch for a ground, defective temperature switch, or overheated cooling system. As a test circuit to check whether the bulb is functioning properly, connect a wire from the ground terminal of the ignition switch to the temperature indicator light circuit. When the ignition is in the START (engine cranking) position, the ground terminal is grounded inside the switch and the bulb will be lit. When the engine is started and the ignition switch is in the ON position, the test circuit is opened and the bulb is then controlled by the temperature switch. Wheels - Chrome Wheel Staining/Pitting/Corrosion Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Staining/Pitting/Corrosion INFORMATION Bulletin No.: 00-03-10-002F Date: April 21, 2011 Subject: Chemical Staining, Pitting, Corrosion and/or Spotted Appearance of Chromed Aluminum Wheels Models: 2012 and Prior GM Cars and Trucks Supercede: This bulletin is being revised to update model years, suggest additional restorative products and add additional corrosion information. Please discard Corporate Bulletin Number 00-03-10-002E (Section 03 - Suspension). Important You may give a copy of this bulletin to the customer. What is Chemical Staining of Chrome Wheels? Figure 1 Chemical staining in most cases results from acid based cleaners (refer to Figure 1 for an example). These stains are frequently milky, black, or greenish in appearance. They result from using cleaning solutions that contain acids on chrome wheels. Soap and water is usually sufficient to clean wheels. If the customer insists on using a wheel cleaner they should only use one that specifically states that it is safe for chromed wheels and does not contain anything in the following list. (Dealers should also survey any products they use during prep or normal cleaning of stock units for these chemicals.) - Ammonium Bifluoride (fluoride source for dissolution of chrome) - Hydrofluoric Acid (directly dissolves chrome) - Hydrochloric Acid (directly dissolves chrome) - Sodium Dodecylbenzenesulfonic Acid - Sulfamic Acid - Phosphoric Acid - Hydroxyacetic Acid Notice Many wheel cleaner instructions advise to take care to avoid contact with painted surfaces. Most customers think of painted surfaces as the fenders, quarter panels and other exterior sheet metal. Many vehicles have painted brake calipers. Acidic wheel cleaners may craze, crack, or discolor the paint on the brake calipers. Damage from wheel cleaners is not covered under the vehicle new car warranty. Soap and water applied with a soft brush is usually all that is required to clean the calipers. Whenever any wheel cleaner is used, it must be THOROUGHLY rinsed off of the wheel with clean, clear water. Special care must be taken to rinse under the hub cap, balance weights, wheel nuts, lug nut caps, between the wheel cladding and off the back side of the wheel. Wheels returned to the Warranty Parts Center (WPC) that exhibit damage from wheel cleaners most often have the damage around and under the wheel weight where the cleaner was incompletely flushed away. Notice Page 3389 Throttle Position Sensor: Service and Repair Throttle Position (TP) Sensor NOTE: Since TP configurations can be mounted interchangeably, be sure to order the correct one for your engine with the identical part number of the one being replaced. REMOVE OR DISCONNECT 1. Electrical connector. 2. Two TP sensor attaching screw assemblies. 3. TP sensor from throttle body assembly. NOTE: The TP sensor is an electrical component and must not be soaked in any liquid cleaner or solvent, as damage may result. INSTALL OR CONNECT 1. With throttle valve in normally closed position, install TP sensor on throttle shaft and rotate counter clockwise to align mounting hole. 2. TP sensor attaching screw assemblies, precoated with appropriate thread.locking compound. Tighten Screw assemblies to 2.0 Nm (18.0 lb. in.). 3. Electrical connector. 4. Check for TP sensor output as follows: ^ Connect scan tool scanner to read TP sensor output voltage. ^ With ignition "ON" and engine stopped, TP sensor voltage should be less than 0.85 volt. If more than 0.85 volt, replace TP sensor. Page 1300 4. Locate the surface for the cylinder release button on the plastic ignition switch housing and center punch a location on the "rib" approximately 3/8" rearward (toward the key entry end) from the cylinder release button, see Figure 3. 5. Using a 1/8" drill bit, carefully drill a pilot hole through the plastic housing only. 6. Using a 9/32" drill bit, carefully drill a larger hole at the pilot location, and slightly into the lock cylinder surface to break the release button retaining spring. 7. Remove portions of the broken spring from the hole using a small pair of needle nose pliers (or other suitable tool) and turn switch over to shake out the release button. 8. Grasp the lock cylinder, remove it from the switch housing. 9. Remove any plastic "flash" from the drilling operations and, using compressed air, blow out the ignition switch assembly. 10. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 11. Install the new cylinder(s) as required by rotating both the cylinder and ignition switch to the "ON" position and pushing the cylinder into the switch. It may be necessary to depress the release button slightly as it passes by the 9/32" hole previously drilled in the housing. 12. Reassemble the ignition switch and instrument panel components as indicated by the appropriate Service Manual. Page 2605 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Diagram Information and Instructions Vehicle Speed Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1555 6. Connect the service harness connector to the actuator and connect the 2-pin connector to the mating connector at the axle. For 1994 to current models, in the case of a complete axle replacement, refer to Figure 1. 7. Route the wiring harness along the existing harness on the right side of the vehicle. Route CKT 241 (BRN) over the top and to the left of the transmission. Secure the harness using plastic ties. 8. For 1995-97 interim vehicles, locate the 4-wire connector (C120) on the left side of the transmission. Splice the BRN wire of the actuator harness into cavity D of CKT 241 (BRN) on the engine side of connector C120. Follow the splicing procedure described in Section 8A (Electrical Diagnosis Repair Procedures) of the applicable Service Manual. Important: The new Fast Axle Actuator requires only 1 splice. Page 1691 Valve Clearance: Adjustments These models have a through bolt instead of a stud and adjusting nut. No adjustment is necessary. Page 3098 Knock Sensor Circuit Diagram Information and Instructions Brake Switch (Cruise Control): Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Diagram Information and Instructions Engine Control Module: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3400 Camshaft Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 170 PCM Connector Pin-Out Locations Idle Speed Control Actuator System Page 2536 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3017 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 264 Idle/Throttle Speed Control Unit: Adjustments Idle Speed Control Actuator Adjustment Procedure: - Before adjusting ISC actuator you must first check the minimum idle speed to be within specifications. Refer to SPECIFICATIONS/IDLE SPEED. (ISC actuator must have vacuum applied so that it is not contacting the throttle lever.) See image VIEW A. - Remove vacuum hose on ISC actuator on warm engine. - Adjust ISC actuated idle speed to 1300 +/- 50 rpm. See image VIEW B. - Install vacuum hose. Page 1114 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3848 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3284 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 317 Disclaimer Page 870 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3126 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 1072 Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 3230 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 2558 Auxiliary Cooling Fan Does Not Operate (Part 2 Of 2) Auxiliary Cooling Fan Runs Continuously Page 474 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3744 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Engine, A/T - Shift/Driveability Concerns/MIL ON Air Filter Element: All Technical Service Bulletins Engine, A/T - Shift/Driveability Concerns/MIL ON Bulletin No.: 04-07-30-013B Date: February 01, 2007 INFORMATION Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007 HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X Supercede: This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 04-07-30-013A (Section 07 - Transmission/Transaxle). The use of an excessively/over-oiled aftermarket, reusable air filter may result in: Service Engine Soon (SES) light on Transmission shift concerns, slipping and damaged clutch(es) or band(s) Engine driveability concerns, poor acceleration from a stop, limited engine RPM range The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur. When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared to a like vehicle with an OEM air box and filter under the same driving conditions to verify the concern. The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty. If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and the air induction hose for contamination of oil prior to making warranty repairs. Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not considered to be warrantable repair items. Page 2974 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3327 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Starting - Revised Procedures for Inop Ignition Cylinder Technical Service Bulletin # 73-01-09 Date: 971001 Starting - Revised Procedures for Inop Ignition Cylinder File In Section: 0 - General Information Bulletin No.: 73-01-09 Date: October, 1997 INFORMATION Subject: New Tumblers for Cylinder Recoding, Revised Repair Procedures for Inoperative Ignition Cylinders (Seized/Won't Rotate), Labor Operation/Time Allowances Models: 1995-97 Buick Skylark, Riviera 1995-97 Chevrolet Cavalier 1997 Chevrolet Corvette, Malibu, Venture 1995-97 Oldsmobile Achieva 1997 Oldsmobile Aurora, Cutlass, Silhouette 1995-97 Pontiac Grand Am, Sunfire 1997 Pontiac Grand Prix, Trans Sport 1995-97 Chevrolet and GMC C/K, S/T Models 1996-97 Chevrolet and GMC G, M/L Vans 1996-97 Oldsmobile Bravada The information in this bulletin concerns new designed tumblers for recoding lock cylinders that use double sided reversible keys, revised procedures for servicing ignition lock cylinders that are seized or not able to rotate and revised labor time guide information and allowances. Parts Information Parts are currently available from GMSPO. Warranty Information Page 471 Fig.1-Symbols (Part 1 Of 3) Page 891 Fig.1-Symbols (Part 1 Of 3) Page 3012 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Ignition System - Distributor Is Now Repairable Distributor: Technical Service Bulletins Ignition System - Distributor Is Now Repairable CHEVROLET 71-65-40 Issued: 05/01/97 SMU - SECTION 6E - REVISED ENHANCED IGNITION SYSTEM DESCRIPTION AND OPERATION SUBJECT: SERVICE MANUAL UPDATE - SECTION 6E - ENGINE CONTROLS REVISED ENHANCED IGNITION SYSTEM DESCRIPTION AND OPERATION MODELS: 1995-97 CHEVROLET AND GMC S/T, M/L, C/K, GMT600, P MODELS 1996-97 OLDSMOBILE BRAVADA WITH 4.3L, 5.0L, 5.7L, 7.4L ENGINE (VINS W, M, R, J - RPOS L35, L30, L31, L29) THIS BULLETIN IS BEING ISSUED TO INFORM TECHNICIANS OF A REVISION TO THE ENHANCED IGNITION SYSTEM DESCRIPTION AND OPERATION. THE DISTRIBUTOR IS NOW REPAIRABLE. TECHNICIANS WILL BE REFERRED TO DISTRIBUTOR OVERHAUL IN ENGINE ELECTRICAL FOR PROPER REPAIR AND REPLACEMENT OF ALL COMPONENTS. Page 2841 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3223 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1196 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Hydraulic System Bleeding Brake Bleeding: Service and Repair Hydraulic System Bleeding Manual Bleeding TWO PERSON PROCEDURE (PREFERRED) Gravity and vacuum bleeding are not recommended for this ABS system. PROCEDURE 1. Raise the vehicle to gain access to the system bleed screws. Install clear tubing on the bleed screws so that air bubbles in the fluid can be seen. NOTE: Never pump the brake pedal as fluid cavitation may occur. 2. Begin by bleeding the system at the right rear wheel, then the left rear, right front and left front. 3. Open one bleed screw at a time 1/2 to 1 full turn. 4. Slowly depress the brake pedal until it reaches its full travel and hold until the bleed screw has been tightened. Release the brake pedal and wait 10-15 seconds for the master cylinder to return to the home position. NOTE: Repeat steps 1 through 4 until approximately 1 pint of brake fluid has been bled from each wheel. Clean brake fluid should be present at each of the wheel bleed screws. Check the master cylinder fluid level every 4 to 6 strokes of the brake pedal to avoid running the system dry. 5. After bleeding all four wheels, use a Tech 1 Scan tool to run 4 functional tests while applying the brake pedal firmly. 6. Rebleed all four wheels using steps 1 through 4 to remove the remaining air from the brake system. 7. Evaluate the brake pedal feel before attempting to drive the vehicle and rebleed as many times as necessary to obtain appropriate pedal feel. Pressure Bleeding SPECIAL TOOL REQUIRED (or equivalent) ^ J-39177, Combination valve depressing tool. PROCEDURE 1. Install pressure bleeder per manufacturers instructions. 2. Install J-39177 if the vehicle is equipped with the metering portion of the combination valve. Remove both dust caps on the combination valve. Install the tool on the end of the combination valve with a brass center pin. 3. Bleed all four wheels beginning at the right rear wheel, then the left rear, right front and left front. Leave the bleed screws open until 1 pint of fluid has been bled out of each wheel. 4. After bleeding all four wheels, remove the combination valve clip. Use a Scan Tool to run 4 functional tests while applying the brake pedal firmly. 5. Repeat steps 1 through 3 then evaluate the pedal feel. 6. Rebleed the wheels as many times as necessary to obtain good pedal feel before attempting to drive the vehicle. A good bleed will use approximately 2 to 3 quarts of brake fluid. NOTE: Never reuse brake fluid after it has been bled through a brake system. General Information The braking system can be bled manually or with pressure bleeding equipment. If bleeding manually, check fluid level frequently. Brake fluid should never be reused. Before driving the vehicle, check brake operation to ensure a firm pedal has been obtained. Brake fluid will damage electrical connections and painted surfaces. Use shop cloths, suitable containers, and fender covers to prevent brake fluid from contacting these areas. Always seal and wipe off brake fluid containers to prevent spills. Manual Page 2237 Valve: Specifications Valve Arrangement FRONT TO REAR 7.4L/V8-454 ......................................................................................................................................... ........................................................... E-I-E-I-E-I-E-I Page 1557 Page 991 Fig.2-Symbols (Part 2 Of 3) Page 678 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3880 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3884 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1205 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1682 Spark Plug: Service and Repair REMOVE OR DISCONNECT Make sure the ignition switch is "OFF." CAUTION: Twist the spark plug boot one-half turn to release It. Pull on the spark plug boot only. Do not pull on the wire or the spark plug lead may be damaged. 1. Spark plug wires and boots. - Label the plug wires. NOTE: These spark plugs have a ceramic Insulator that Is about 1/8 Inch longer than earlier model spark plugs. Be sure to use a spark plug socket that Is deep enough for this longer length spark plug. Failure to do so could cause cracking of the Insulator and arcing In side the spark plug, resulting in engine miss. 2. Spark plugs using a 5/8-inch socket. Inspect Each spark plug for wear and gap. Refer to Testing and Inspection. Spark plugs should be gapped to 0.035 inch. INSTALL OR CONNECT CAUTION: Make sure each plug threads smoothly Into the cylinder head and is fully seated. Cross-threading or failing to fully seat spark plugs can cause overheating of the spark plugs, exhaust blow-by, or thread damage. 1. Spark plugs. Tighten Spark plugs to 15 Nm (11 lbs. ft.). 2. Wire and boot assemblies. Refer to Ignition Cable / Service and Repair for precautions. Page 1381 Ignition Switch Lock Cylinder: Service and Repair The procedure has been updated by TSB# 73-01-09 Important: This new procedure involves drilling a hole through the plastic ignition switch and into the lock cylinder slightly to break or access a cylinder release button retaining spring (similar to G, J and N models). The removal of the broken spring and then the release button will allow the switch to be reused. 1. Remove the necessary trim panels to gain access to the instrument panel mounted switch (refer to information in "Body and Accessories Section, Instrument Panel, Gauges and Consoles"). a. On instrument panel mounted N models (Malibu and Cutlass), the switch and cylinder can be accessed after removing the instrument cluster assembly and positioning the switch/cylinder upward in the cavity for the cluster assembly. b. On Corvette models, the switch and cylinder can be accessed after removing the knee bolster from the lower instrument panel area and positioning the switch/cylinder downward from its location on the instrument panel. 2. Loosen switch from instrument panel and disconnect the electrical connections, BUT NOT the cable connection for BTSI (Brake/Transmission Shift Interlock). 3. Protect the immediate work area with a fender cover or other suitable material. 4. Locate the surface for the cylinder release button on the plastic ignition switch housing and center punch a location on the "rib" approximately 3/8" rearward (toward the key entry end) from the cylinder release button, see Figure 3. 5. Using a 1/8" drill bit, carefully drill a pilot hole through the plastic housing only. 6. Using a 9/32" drill bit, carefully drill a larger hole at the pilot location, and slightly into the lock cylinder surface to break the release button retaining spring. 7. Remove portions of the broken spring from the hole using a small pair of needle nose pliers (or other suitable tool) and turn switch over to shake out the release button. 8. Grasp the lock cylinder, remove it from the switch housing. 9. Remove any plastic "flash" from the drilling operations and, using compressed air, blow out the ignition switch assembly. 10. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 11. Install the new cylinder(s) as required by rotating both the cylinder and ignition switch to the "ON" position and pushing the cylinder into the switch. It may be necessary to depress the release button slightly as it passes by the 9/32" hole previously drilled in the housing. 12. Reassemble the ignition switch and instrument panel components as indicated by the appropriate Service Manual. Specifications Transmission Temperature Sensor/Switch: Specifications COMPONENT ..................................................................................................................................... ...................................................... Torque/Ft.Lbs. Temperature Sensor To Valve Body ................................................................................................... ................................................................................. 3 Page 3633 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Engine, A/T - Shift/Driveability Concerns/MIL ON Air Filter Element: Customer Interest Engine, A/T - Shift/Driveability Concerns/MIL ON Bulletin No.: 04-07-30-013B Date: February 01, 2007 INFORMATION Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007 HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X Supercede: This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 04-07-30-013A (Section 07 - Transmission/Transaxle). The use of an excessively/over-oiled aftermarket, reusable air filter may result in: Service Engine Soon (SES) light on Transmission shift concerns, slipping and damaged clutch(es) or band(s) Engine driveability concerns, poor acceleration from a stop, limited engine RPM range The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur. When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared to a like vehicle with an OEM air box and filter under the same driving conditions to verify the concern. The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty. If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and the air induction hose for contamination of oil prior to making warranty repairs. Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not considered to be warrantable repair items. Page 1482 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 20 - HVAC Actuator - Inflatable Restraint Sensing and Diagnostic Module (SDM) - Any AIR BAG module - Seatbelt Lap Anchor Pretensioner - Seatbelt Retractor Pretensioner - An SIR system connection or connector condition resulting in the following DTCs being set: B0015, B0016, B0019, B0020, B0022, or B0023 - Powertrain Control Module (PCM) - Remote Control Door Lock Receiver (RCDLR) - Transmission Control Module (TCM) Correction Important DO NOT replace the control module, wiring or component for the following conditions: - The condition is intermittent and cannot be duplicated. - The condition is present and by disconnecting and reconnecting the connector the condition can no longer be duplicated. Use the following procedure to correct the conditions listed above. 1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any existing history or current DTCs from all of the control modules (refer to SI). ‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the connector(s) of the control module/component which may be causing the condition (refer to SI). ‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control module/component which may be causing the condition (refer to SI). 2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component Connector End Views and Component Locator documents to locate and disconnect the affected harness connector(s) which are causing the condition. Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the actual electrical contact is being made. In less severe cases it may be unable to be seen or identified without the use of a magnifying glass. Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown, as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush that is dedicated to the repair of the conditions in this bulletin. 3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side and the harness side of the affected connector(s). 4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present. 5. Attempt to duplicate the condition by using the following information: - DTC Diagnostic Procedure - Circuit/System Description - Conditions for Running the DTC - Conditions for Setting the DTC - Diagnostic Aids - Circuit/System Verification ‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated, then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI). Repair Order Documentation Automatic Transmission Backup Lamp Switch: Locations Automatic Transmission HD Electronic 4-Speed Automatic Overdrive Transmission Page 3885 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 1199 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3469 A. On G, J and N Models: DO NOT REMOVE THE STEERING COLUMN as indicated in the Service Manual procedure. 1. Remove the tilt lever, upper and lower column covers. 2. Drill hole in module housing as indicated in the illustration using a short drill bit (1/8" followed by 9/32") and 90 degree drill motor or go degree drill attachment to break or access the retaining spring for the lock cylinder button, see Figure 2. 3. Using a pick or needle nose pliers, remove the retaining spring from the hole. 4. Using pliers, grasp and remove the retaining button for the cylinder. 5. Remove the cylinder from the housing. 6. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 7. Install the new cylinder and reinstall the steering column components. B. On U, W, and light duty trucks, follow the Service Manual procedure for keys missing, or cylinders won't rotate. Procedure: Instrument Panel Mounted Switches Important: This new procedure involves drilling a hole through the plastic ignition switch and into the lock cylinder slightly to break or access a cylinder release button retaining spring (similar to G, J and N models). The removal of the broken spring and then the release button will allow the switch to be reused. 1. Remove the necessary trim panels to gain access to the instrument panel mounted switch (refer to information in "Body and Accessories Section, Instrument Panel, Gauges and Consoles"). a. On instrument panel mounted N models (Malibu and Cutlass), the switch and cylinder can be accessed after removing the instrument cluster assembly and positioning the switch/cylinder upward in the cavity for the cluster assembly. b. On Corvette models, the switch and cylinder can be accessed after removing the knee bolster from the lower instrument panel area and positioning the switch/cylinder downward from its location on the instrument panel. 2. Loosen switch from instrument panel and disconnect the electrical connections, BUT NOT the cable connection for BTSI (Brake/Transmission Shift Interlock). 3. Protect the immediate work area with a fender cover or other suitable material. Front Differential Output Shaft Seals - Replacement Constant Velocity Joint Boot: All Technical Service Bulletins Front Differential Output Shaft Seals Replacement File In Section: 4 - Drive Axle Bulletin No.: 56-43-02 Date: October, 1995 INFORMATION Subject: Replacing Front Differential Output Shaft Seals Models: 1988-96 Chevrolet and GMC Truck K Models Important: A copy of this service bulletin should be given to the appropriate warranty administration personnel. The purpose of this bulletin Is to discuss the following two important points as they relate to front differential output shaft seal replacement: ^ Proper Labor Operation Usage. ^ Proper Drive Axle (Halfshaft) Handling To Prevent Damage to the New Inboard and Outboard Boot (Seal). A/T - DEXRON(R)-VI Fluid Information Fluid - A/T: Technical Service Bulletins A/T - DEXRON(R)-VI Fluid Information INFORMATION Bulletin No.: 04-07-30-037E Date: April 07, 2011 Subject: Release of DEXRON(R)-VI Automatic Transmission Fluid (ATF) Models: 2008 and Prior GM Passenger Cars and Light Duty Trucks 2003-2008 HUMMER H2 2006-2008 HUMMER H3 2005-2007 Saturn Relay 2005 and Prior Saturn L-Series 2005-2007 Saturn ION 2005-2008 Saturn VUE with 4T45-E 2005-2008 Saab 9-7X Except 2008 and Prior Chevrolet Aveo, Equinox Except 2006 and Prior Chevrolet Epica Except 2007 and Prior Chevrolet Optra Except 2008 and Prior Pontiac Torrent, Vibe, Wave Except 2003-2005 Saturn ION with CVT or AF23 Only Except 1991-2002 Saturn S-Series Except 2008 and Prior Saturn VUE with CVT, AF33 or 5AT (MJ7/MJ8) Transmission Only Except 2008 Saturn Astra Attention: DEXRON(R)-VI Automatic Transmission Fluid (ATF) is the only approved fluid for warranty repairs for General Motors transmissions/transaxles requiring DEXRON(R)-III and/or prior DEXRON(R) transmission fluids. Supercede: This bulletin is being revised to update information. Please discard Corporate Bulletin Number 04-07-30-037D (Section 07 - Transmission/Transaxle). MANUAL TRANSMISSIONS / TRANSFER CASES and POWER STEERING The content of this bulletin does not apply to manual transmissions or transfer cases. Any vehicle that previously required DEXRON(R)-III for a manual transmission or transfer case should now use P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case Fluid. Some manual transmissions and transfer cases require a different fluid. Appropriate references should be checked when servicing any of these components. Power Steering Systems should now use P/N 9985010 labeled Power Steering Fluid. Consult the Parts Catalog, Owner's Manual, or Service Information (SI) for fluid recommendations. Some of our customers and/or General Motors dealerships/Saturn Retailers may have some concerns with DEXRON(R)-VI and DEXRON(R)-III Automatic Transmission Fluid (ATF) and transmission warranty claims. DEXRON(R)-VI is the only approved fluid for warranty repairs for General Motors transmissions/transaxles requiring DEXRON(R)-III and/or prior DEXRON(R) transmission fluids (except as noted above). Please remember that the clean oil reservoirs of the J-45096 - Flushing and Flow Tester machine should be purged of DEXRON(R)-III and filled with DEXRON(R)-VI for testing, flushing or filling General Motors transmissions/transaxles (except as noted above). DEXRON(R)-VI can be used in any proportion in past model vehicles equipped with an automatic transmission/transaxle in place of DEXRON(R)-III (i.e. topping off the fluid in the event of a repair or fluid change). DEXRON(R)-VI is also compatible with any former version of DEXRON(R) for use in automatic transmissions/transaxles. DEXRON(R)-VI ATF General Motors Powertrain has upgraded to DEXRON(R)-VI ATF with the start of 2006 vehicle production. Current and prior automatic transmission models that had used DEXRON(R)-III must now only use DEXRON(R)-VI. Service and Repair Fuel Pressure Release: Service and Repair PROCEDURE: NOTE: A constant bleed feature in the pressure regulator relieves pressure when engine is turned "OFF." - Disconnect negative battery terminal to avoid possible fuel discharge if an accidental attempt is made to start the engine. - Loosen fuel filler cap to relieve tank vapor pressure. - The internal constant bleed feature of the TBI relieves fuel pump system pressure when the engine is turned "OFF." Therefore, NO further pressure relief procedure is required. Page 3706 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Engine - Cold Knock, Replace Oil Filter/Bearings/PROM Crankshaft Main Bearing: All Technical Service Bulletins Engine - Cold Knock, Replace Oil Filter/Bearings/PROM File In Section: 6 - Engine Bulletin No.: 37-61-05A Date: October, 1995 Subject: Cold Engine Knock (Replace Oil Filter/Bearings/PROM) Models: 1990-95 Chevrolet and GMC Truck C/K, R/V, S/T, M/L, G, P Models 1991-92 Oldsmobile Bravada with 4.3L (VIN Z - RPO LB4), 5.7L (VIN K - RPO L05), 7.4 (VIN N - RPO L19) Engine This bulletin is being revised to add the 1995 model year information. Please discard Corporate Bulletin Number 37-61-05 (Section 6 - Engine). Condition Some late model truck engines have been reported to exhibit "cold knock" on start up. "Cold Knock" usually occurs after the vehicle has been completely warmed up, then parked for 8 or more hours in ambient temperatures of 35° F or less. "Cold knock" can be separated into three distinct categories. 1. Short Duration - Harsh, deep metallic knock that usually lasts from 1 to 10 seconds. Generally classified as a bearing or rod knock. 2. Valve Train - Light clatter, tick or click that may last up to 1 minute. 3. Piston Slap - Metallic knock that occurs only under load. Piston slap may last as long as 5 minutes. Correction Category A: Short Duration Knock This matrix describes the repair for each affected model year and engine. Specific information for each affected model year and engine is supplied. Page 3948 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2928 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3337 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3398 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 2019 onto the subject vehicle. - After match mounting, the tire/wheel assembly must be rebalanced. If match mounting tires to in-spec wheels produces assembly values higher than these, tire replacement may be necessary. Replacing tires at lower values will probably mean good tires are being condemned. Because tires can sometimes become temporarily flat-spotted, which will affect force variation, it is important that the vehicle be driven at least 16 km (10 mi) prior to measuring. Tire pressure must also be adjusted to the usage pressure on the vehicle's tire placard prior to measuring. Most GM vehicles will tolerate radial force variation up to these levels. However, some vehicles are more sensitive, and may require lower levels. Also, there are other tire parameters that equipment such as the Hunter GSP9700 cannot measure that may be a factor. In such cases, TAC should be contacted for further instructions. Important - When mounting a GM wheel to a wheel balancer/force variation machine, always use the wheel's center pilot hole. This is the primary centering mechanism on all GM wheels; the bolt holes are secondary. Usually a back cone method to the machine should be used. For added accuracy and repeatability, a flange plate should be used to clamp the wheel onto the cone and machine. This system is offered by all balancer manufacturers in GM's dealer program. - Any type of service equipment that removes tread rubber by grinding, buffing or truing is NOT recommended, and may void the tire warranty. However, tires may have been ground by the tire company as part of their tire manufacturing process. This is a legitimate procedure. Steering Wheel Shake Worksheet When diagnosing vibration concerns, use the following worksheet in conjunction with the appropriate Vibration Analysis-Road testing procedure in the Vibration Correction sub-section in SI. Page 3266 5-Speed Manual Transmission VSS 4WD Or AWD Door Switch - Dome Light Stays On/Dead Battery/No Start Door Switch: Customer Interest Door Switch - Dome Light Stays On/Dead Battery/No Start File In Section: 8 - Chassis/Body Electrical Bulletin No.: 56-82-05 Date: September, 1995 Subject: Dome Lamp Stays On, Dead Battery, No Start (Shim Door Trim Panel Push Nail) Models: 1995 Chevrolet and GMC Truck C/K Models 1995 Topkick/Kodiak Models Condition Dome lamp stays on, with doors closed and headlight rotary wheel in the off position. Cause Dome lamp switch plunger is not pushed in far enough. There is too large a gap between the dome lamp switch plunger and the door panel convex push nail. Correction Shim out door panel push nail with color keyed shims available through GMSPO. Service Procedure Page 1441 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3047 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Locations Relay Box: Locations Auxiliary Battery Wiring Page 3439 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 370 12. Using template (Figure 4), mark cutting lines on the upper evaporator case using a china marker or equivalent. Do not remove the locating tabs from the templates, they are needed to position the cut area for the access doors (Figure 1). Page 666 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 1411 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3479 Ignition Switch Lock Cylinder: Service and Repair The procedure has been updated by TSB# 73-01-09 Important: This new procedure involves drilling a hole through the plastic ignition switch and into the lock cylinder slightly to break or access a cylinder release button retaining spring (similar to G, J and N models). The removal of the broken spring and then the release button will allow the switch to be reused. 1. Remove the necessary trim panels to gain access to the instrument panel mounted switch (refer to information in "Body and Accessories Section, Instrument Panel, Gauges and Consoles"). a. On instrument panel mounted N models (Malibu and Cutlass), the switch and cylinder can be accessed after removing the instrument cluster assembly and positioning the switch/cylinder upward in the cavity for the cluster assembly. b. On Corvette models, the switch and cylinder can be accessed after removing the knee bolster from the lower instrument panel area and positioning the switch/cylinder downward from its location on the instrument panel. 2. Loosen switch from instrument panel and disconnect the electrical connections, BUT NOT the cable connection for BTSI (Brake/Transmission Shift Interlock). 3. Protect the immediate work area with a fender cover or other suitable material. 4. Locate the surface for the cylinder release button on the plastic ignition switch housing and center punch a location on the "rib" approximately 3/8" rearward (toward the key entry end) from the cylinder release button, see Figure 3. 5. Using a 1/8" drill bit, carefully drill a pilot hole through the plastic housing only. 6. Using a 9/32" drill bit, carefully drill a larger hole at the pilot location, and slightly into the lock cylinder surface to break the release button retaining spring. 7. Remove portions of the broken spring from the hole using a small pair of needle nose pliers (or other suitable tool) and turn switch over to shake out the release button. 8. Grasp the lock cylinder, remove it from the switch housing. 9. Remove any plastic "flash" from the drilling operations and, using compressed air, blow out the ignition switch assembly. 10. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 11. Install the new cylinder(s) as required by rotating both the cylinder and ignition switch to the "ON" position and pushing the cylinder into the switch. It may be necessary to depress the release button slightly as it passes by the 9/32" hole previously drilled in the housing. 12. Reassemble the ignition switch and instrument panel components as indicated by the appropriate Service Manual. Page 1063 Throttle Position Sensor: Testing and Inspection This check should be performed when TP sensor attaching parts have been replaced. A Tech 1 scan tool can be used to read the TP sensor output voltage, or: 1. Connect digital voltmeter J 39200 or equivalent, from TP sensor connector terminal "B" (BLK wire) to terminal "C" (DK BLU wire). 2. With ignition "ON," engine stopped, the TP sensor voltage should be less than 0.85 volt if more than 0.85 volt verify free throttle movement. If still more than 0.85 volt, replace TP sensor. 3. Remove the voltmeter and jumpers, reconnect the TP sensor connector to the sensor. Page 1177 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 900 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 2938 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids A/C Compressor - Loud Knocking Noise Refrigerant Filter: Customer Interest A/C Compressor - Loud Knocking Noise File in Section: 1 - HVAC Bulletin No.: 56-12-01 Date: February, 1995 SUBJECT: Loud Knock from A/C Compressor (Replace Compressor and Thermal Expansion Valve) MODELS: 1994-95 Chevrolet C/K Models built before VIN breakpoint SJ300349 1994-95 GMC Truck C/K Models built before VIN breakpoint SJ701253 with Rear A/C (RPO C69) or Rear Heater and A/C (RPOs C36, C69) CONDITION Some owner's of the above listed vehicles may comment that the A/C compressor has developed a loud knocking noise. The A/C system will continue to cool. CAUSE When the rear A/C system is shut off, a refrigerant flood back condition may occur through the rear A/C system. This flooding degreases the internal parts of the compressor resulting in rapid slider block wear and the resulting loud knocking noise. A poor contact between the TXV capillary tube and the rear evaporator outlet tube can allow the TXV to remain open when the rear system is not in use. The open TXV may allow liquid refrigerant to flood back through the rear system (liquid line, TXV, evaporator, rear suction line) and subsequently flood the compressor. CORRECTION Replace the A/C compressor, the thermal expansion valve (TXV), and add an in-line filter. Service Procedure 1. Recover the R-134a refrigerant charge (Section 1-B of Service Manual). 2. Replace the compressor and balance the PAG lubricant in the system following the procedures in the vehicle service manual. 3. Install an in-line filter in the liquid line after the condenser and before the "Y" in the line separating the front and rear systems. 4. Remove, inspect and clean the orifice tube for the front system. It is located in the liquid line after the "Y" joint. 5. Replace the orifice tube. 6. Disconnect seat belt and remove rear bench seat. 7. Remove the right second passenger seat shoulder belt retainer from the right side C-pillar. 8. Remove the (5) screws from the right side C-pillar trim. 9. Remove the (2) screws securing the right side lower trim panel to the C-pillar. 10. Remove the (5) screws securing the D-pillar covers. 11. Lift the right side lower trim panel and roll forward to remove, this exposes the rear HVAC evaporator case module. Page 1510 Transmission Range (TR) Pressure Switch Assembly Circuit Check Transmission Range (TR) Signal CIRCUIT DESCRIPTION The Transmission Range (TR) switch assembly consists of five normally open pressure switches and is attached to the valve body. The Powertrain Control Module (PCM) supplies battery voltage to each range signal. By grounding one or more of these circuits through various combinations of the pressure switches, the PCM detects what manual valve position has been selected by the vehicle operator. With ignition "ON" and engine "OFF," P/N will be indicated. When transmission electrical connector is disconnected, the ground potential for the three range signals to the PCM will be removed, and with ignition "ON," D2 will be indicated. DIAGNOSTIC TROUBLE CODE (DTC) CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic charts. 1. This test checks the indicated range signal to the manual valve position actually selected. 2. This test checks for correct Voltage from the PCM to the transmission external connector. 3. This test checks for a short to ground from the PCM to the-transmission external connector in any one of the three circuits. DIAGNOSTIC AIDS Refer to accompanying chart for various A/B/C range combinations. Check all wiring connectors for proper terminal tension. Refer to Automatic Transmission for further information. Page 3078 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3840 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1910 Fuse: Application and ID Underhood Fuse/Relay Center Underhood Fuse/Relay Center Page 3053 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 402 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 2843 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 893 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 360 13. Using template (Figure 5), mark cutting lines on the lower evaporator case using a china marker or equivalent (Figure 1). 14. Cut through the plastic upper evaporator case and the lower evaporator case following the marked outlines of the templates to create two access doors (Figure 1). Do not cut rear edge of either access door (Figure 4 and 5). Use a hot knife or a small (1/2" dia.) rotary abrasive cutting wheel. Page 3804 results from the alteration or modification of a vehicle using non-GM approved parts or accessories. Dealers should be especially cautious of accessory companies that claim the installation of their product will not void the factory warranty. Many times these companies have even given direction on how to quickly disassemble the accessory in an attempt to preclude the manufacturer from finding out that is has been installed. Any suspect repairs should be reviewed by the Fixed Operations Manager (FOM), and in Canada by the Warranty Manager (WM) for appropriate repair direction. If it is decided that a goodwill repair is to be made on the vehicle, even with the installation of such non-GM approved components, the customer is to be made aware of General Motors position on this issue and is to sign the appropriate goodwill documentation required by General Motors. It is imperative for dealers to understand that by installing such devices, they are jeopardizing not only the warranty coverage, but also the performance and reliability of the customer's vehicle. Disclaimer Page 2181 EXAMPLE 2: The lower insert is stamped STD (standard) and the upper is stamped 0.0010". The undersize for a STD bearing is 0. Divide 0 by 2 to get 0. Divide 0.0010" by 2 to get 0.0005". Add 0 and 0.0005" together to calculate the bearing undersize, which is 0.0005" in this case. 13. Add the original bearing undersize calculated in step 12 to the clearance measured and written down in step 9. For example, if a clearance of 0.0030" was measured with plastigage in step 9 and the calculated bearing undersize from step 12 was 0.0005", the bearing clearance for that particular main journal is equal to 0.0030" plus 0.0005". The bearing clearance would be 0.0035" in this case. 14. Determine which of the combinations of two sizes of replacement bearings will produce the desired clearance. The two sizes available are 0.001" and 0.002". One insert of each size may be combined to produce an intermediate undersize of 0.0015". Subtract the replacement bearing size from the actual clearance to determine which bearing should be used. The bearing that should be used is the one which gives a clearance closer to 0.0008" than to 0.0028". The clearance must not be less than 0.0008". Using the example from step 11, the actual clearance is 0.0035". Subtracting 0.001" from 0.0035" will give a clearance of 0.0025", just barely within the required range. Subtracting 0.002" from 0.0035" will give a clearance of 0.0015". The 0.002" undersize bearing set would be the one to use in this case since it gives a clearance closer to 0.0008", but not less. 15. Install the replacement upper main bearing insert using tool J 8080. 16. Install the replacement lower main bearing insert in the main bearing cap. Lay a piece of plastigage across the width of the lower main bearing insert (same as step 5). 17. Repeat steps 7, 8 and 9. 18. Measuring the plastigage with the scale on the envelope, verify the clearance of the replacement bearings is within the range of 0.001" to 0.003". 19. Repeat steps 4 through 16 for each main bearing. 20. Thrust the crankshaft forward and backward several times to seat the thrust bearing. 21. Reinstall oil pump; torque to 88 N.m (65 lb ft). 22. Reinstall the oil pan and other hardware. 23. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 24. Install fuel pump fuse, start engine, check for leaks or unusual noises. 25. Road test vehicle, check for leaks or unusual noises. THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE OUT OF THE VEHICLE Recommended for K, S and T vehicles. 1. Remove the engine from the vehicle using the appropriate service manual procedure. 2. Mount the engine on an engine stand, flip the engine so the oil pan is facing up. 3. Remove the oil pan. 4. Remove the oil pump and shield. 5. Remove the dipstick tube. 6. Remove one (1) main bearing cap (must do one at a time). 7. Plasti-gage bearing. 8. If the bearing clearance is out of specification (clearance greater than 0.003 inches), remove upper main bearing from the block. 9. Check the size of the original bearing. 10. Determine what combination of new bearings are required to get the clearance in the acceptable range of 0.0008 inches to 0.0028 inches. See steps Page 2142 Wheel Fastener: Specifications Wheel Stud Nut Wheel Stud Nut Vehicles (Single) With 8 lugs 120 ft.lb Vehicles (Dual) With 8 Lugs 140 ft.lb Vehicles (Dual) With 10 Lugs 175 ft.lb Page 941 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Capacity Specifications Refrigerant Oil: Capacity Specifications REFRIGERANT OIL DISTRIBUTION The Harrison HT-6 compressor system used on all models requires polyalkaline glycol (PAG) refrigerant oil in the quantities listed below: - Without Aux. A/C - 240 ml (8 fl oz) - With Aux. A/C - 330 ml (11 fl oz) New oil quantities must be added to the system during component replacement and conditions stated as follows: - With no signs of excessive oil leakage, add: A. All Compressors (drain and measure the oil) - If less than 30 ml (1 fl oz) is drained-add 60 ml (2 fl oz) to the new compressor. - If more than 30 ml (1 fl oz) is drained-add same amount that was drained to the new compressor. B. Accumulator-Add 105 ml (3.5 fl oz) of new oil to the replacement accumulator to compensate for oil retained by original accumulator desiccant and bag assemblies. The accumulator should only be replaced if leaking due to a perforation, damaged O-ring seal seat, or damaged threads. C. Evaporator-Add 90 ml (3 fl oz) of new refrigerant oil. D. Condenser-Add 30 ml (1 fl oz) of new refrigerant oil. REFRIGERANT OIL LOSS DUE TO A LARGE LEAK If the refrigerant charge is abruptly lost due to a large refrigerant leak, approximately 90 ml (3 fl oz) of refrigerant oil will be carried out of the system suspended in the refrigerant. Any failure that caused a abrupt refrigerant discharge will experience this oil loss. Failures that allow the refrigerant to seep or bleed off over time do not experience this oil loss. Upon replacement of a component that caused a large refrigerant leak, add 90 ml (3 fl oz) of new polyalkaline glycol (PAG) refrigerant oil plus the desired amount of oil for the particular component. Page 2854 Engine Control Module: Service and Repair Fuel Module (Located Above Blower Motor Assembly) Replacement of the Powertrain Control Module (PCM) consists of a service controller, without a PROM (MEM-CAL). If the diagnostic procedures require the PCM to be replaced, the PCM, PROM (MEM-CAL) should be checked for the correct part number. If they are correct, remove the PROM (MEM-CAL), and install them in the control module. The control module will not contain a PROM (MEM-CAL). IMPORTANT: When replacing a production PCM with a control module, transfer the broadcast code and production PCM part number to the control module label. Do not record information on the access cover. NOTE: The ignition must be "OFF," and disconnect negative battery cable when disconnecting or reconnecting the PCM connector, to prevent internal damage to the PCM. NOTE: To prevent possible Electrostatic Discharge damage to the PCM, Do Not touch the connector pins or soldered components on the circuit board. REMOVE OR DISCONNECT 1. Negative battery cable. 2. Glove box. 3. PCM harness connectors. 4. PCM from tray. 5. Mounting brackets and modules if equipped. 6. Access cover PROM (MEM-CAL). INSTALL OR CONNECT 1. PROM (MEM-CAL) access cover in new PCM. 2. Mounting brackets and modules if equipped. 3. PCM into tray until clips lock. 4. PCM harness connectors. 5. Glove box. 6. Negative battery cable. 7. Perform functional check. Page 2684 Radiator: Technical Service Bulletins Cooling - Radiator Repair/Replacement Guidelines File In Section: 06 - Engine/Propulsion System Bulletin No.: 99-06-02-017 Date: October, 1999 INFORMATION Subject: Radiator Repair/Replacement Guidelines Models: 2000 and Prior Passenger Cars and Trucks If repair of an aluminum/plastic radiator is required, it is recommended that the following guidelines be followed: For Vehicles Under Warranty For aluminum/plastic radiators that have damage to the face of the core including bent fins, punctures, cuts, leaking tubes or header tubes, the aluminum radiator core section should be replaced with a new one. In these cases, if both of the plastic tanks are not damaged, they can be reused with the new core. If one or both of the plastic tanks are damaged along with the core, it is recommended that a complete new radiator assembly be installed. Warranty repairs for leaks at the tank to header (gasket leaks), broken/cracked plastic tanks, cross threaded or leaking oil coolers should be repaired without replacing the complete radiator. This type of repair should be handled by the radiator repair facility in your area. Many of these radiator repair facilities are members of the National Automotive Radiator Service Association (NARSA) who follow industry and General Motors guidelines when repairing radiators. These facilities have the special tools, tanks and pressurizing equipment needed to properly test the repaired radiator prior to returning it to the dealership. Many of these facilities receive the repair components directly from General Motors. The sublet expense for a new radiator or the repair of the radiator under warranty should be handled following normal procedures. For Vehicles No Longer Under Warranty The GM released epoxy repair kit referenced in previous publications is no longer available. Repairs to the radiator, rather than replacement, is strictly at the owner's discretion. Page 1870 Technical Service Bulletin # 631209 Date: 960501 A/C - R12 or R134a Service Recommendations File In Section: 1 - HVAC Bulletin No.: 63-12-09 Date: May, 1996 INFORMATION Subject: Service Issues for Vehicles with R12 or R134a Air Conditioning Systems Models: 1988-96 Passenger Cars and Trucks R12 Service Recommendations As you know, production of R12 refrigerant ceased on December 31, 1995. Although R12 will no longer be manufactured, there is a reserve supply of R12 available. This reserve, along with strict A/C repair service adherence to proper refrigerant recycling procedures, should assure continued availability to meet consumers' needs. R12 can and should continue to be used to service vehicles built with R12 A/C systems as long as it is available. If R12 is no longer available or affordable, a system retrofit utilizing R134a is recommended. R134a IS THE ONLY SUBSTITUTE REFRIGERANT RECOMMENDED BY GM FOR USE IN GM VEHICLE A/C SYSTEMS, AND THEN ONLY AFTER FOLLOWING THE PROPER RETROFIT PROCEDURES FOR THE SPECIFIC MODEL. All new vehicle manufacturers have chosen R134a for retrofit. One of the key reasons is to protect both the service industry and consumers from the high costs that would result from purchasing equipment necessary to service multiple refrigerants. This position also reduces the threat of recycled refrigerant contamination. GM currently offers a simple, low cost R12 to R134a retrofit on many of its late model, front wheel drive passenger cars. Dealers should discuss this capability with owners of these specific models, listed in Retrofit Corporate Bulletin # 43-12-07D, whenever a repair to the A/C refrigerant system is required. Early retrofit of these specific models will aid in prolonging availability of the R12 supply and provide dealer service technicians the opportunity to become more familiar with the proper procedures for performing a retrofit. Remember - R12 and R134a refrigerant are not interchangeable! They cannot be mixed together. In fact, despite the claims of some refrigerant manufacturers, no proposed R12 refrigerant substitute can be added to, mixed with or used to "top off" an R12 system. Under provisions of law covering the service of refrigerants, mixing dissimilar refrigerant products during service is prohibited. To Summarize GM R12 Service Policy 1. Service R12 vehicles with good quality new or recycled R12 as long as it is available. 2. Purchase R12 from a reliable supplier. GMSPO has a supply of high quality R12 available. Dealers are requested to use only R12 supplied by GMSPO for warranty repairs. This high quality refrigerant will insure system performance and avoid the possibility of introducing contaminated material into the customer's A/C system. 3. Carefully test recovered R12 using the PureGuard monitor. On recovery equipment not protected by the PureGuard, always test the recovery cylinder prior to recharging a vehicle A/C system. 4. Discuss the R12 to R134a retrofit option with owners of GM vehicles listed in Retrofit Corporate Bulletin # 43-12-07D. Provide owner with a copy of the pamphlet "Converting Your Auto Air Conditioning System to Use the New Refrigerant". 5. Become familiar with retrofit procedures and exercise care in the handling of dissimilar refrigerants to prevent contamination. R134A Service Recommendations When servicing a previously retrofitted vehicle, there is concern that if all of the R12 is not completely removed prior to the retrofit procedure, it could contaminate your R134a equipment and recovery tank when a subsequent A/C repair is performed. Although the number of retrofits being performed today is minimal, the volume will increase as R12 prices rise. GM Service Technology Group is in the process of field testing a new R134a refrigerant purity tester similar to the PureGuard R12 refrigerant tester you now use. This new tool will mount to your ACR4 R134a Recovery Recycle and Recharge cart and sample all R134a refrigerant prior to recovery. It is expected that testing of this tool will be completed this year. This new tool, the Pureguard 2, will also test vehicles and your recycle tank for air contamination, which is threatening A/C system performance. High levels of air have been found in the recovery tanks on a number of R12 and R134a recovery carts. Air contamination is caused by improper recovery Page 259 Fuel Pump Relay: Testing and Inspection RESULTS OF INCORRECT FUEL PUMP RELAY OPERATION - An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold. As a backup system to the fuel pump relay, the fuel pump is also turned "ON" by an oil pressure switch. The oil pressure switch will turn "ON" the fuel pump as soon as oil pressure reaches about 28 kPa (4 psi). Page 75 Fig.2-Symbols (Part 2 Of 3) Page 903 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3139 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1475 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 2141 Disclaimer Page 243 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 1434 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3329 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1099 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1064 Throttle Position Sensor: Adjustments The Throttle Position (TP) Sensor is not adjustable. With the ignition "ON" and the engine stopped, the TPS voltage should be less than 0.85 volts. If more than 0.85 volts, the TPS must be replaced. Page 3614 Fig.1-Symbols (Part 1 Of 3) Page 694 Cruise Control Gasoline Engines (Part 1 Of 2) Page 1183 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3278 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 761 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2051 Refer to the appropriate section of SI for specifications and repair procedures that are related to the vibration concern. Disclaimer Page 1253 Fig.2-Symbols (Part 2 Of 3) Page 416 Temp Sensor Circuit Wiring Locations Underhood Fuse/Relay Center Page 2869 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1622 Idle Speed: Adjustments Minimum Idle Speed Adjustment 1. Check controlled idle speed and perform idle speed control system check first. 2. Set parking brake and block drive wheels. 3. Start engine and bring it to normal operating temperature 85°C-100°C (185°F-212°F). Turn engine "OFF." 4. Remove air cleaner, adapter and gaskets. Check that the throttle lever is not being bound by the throttle or cruise control cables. 5. With IAC valve connected, Connect Tech 1 and command IAC counts to 0. 6. With ignition "ON," engine stopped, disconnect IAC valve electrical connector. (This disables IAC valve in seated position.) Care should be taken to pull the connector straight out so that the moment of electrical disconnect is the same for all the pins. Otherwise the pintle may move as the connector is removed. 7. Start engine. With transmission in neutral, allow engine rpm to stabilize. Make sure that the ISC actuator is not contacting the throttle lever. If so refer to "IAC Actuator System Check." 8. Check rpm against specifications. Disregard IAC counts on Tech 1 scan tool with the IAC disconnected. If the engine has less than 500 miles or is checked at altitudes above 1500 feet, the idle rpm with a seated IAC valve should be lower than values above. 9. If the minimum idle speed is within specifications, no further check is required. 10. If the minimum idle speed is not within specifications, perform the following procedures: Idle Stop Screw 11. If present, remove stop screw plug by piercing it with an awl, then applying leverage. The screw is covered to discourage unauthorized adjustments. 12. With engine at normal operating temperature 85°C-100°C (185°F-212°F), adjust stop screw to obtain nominal rpm per specifications with seated IAC valve. 13. Turn ignition "OFF," and reconnect IAC valve electrical connector. 14. Disconnect Tech 1 scan tool or tachometer. 15. Use silicon sealant or equivalent to cover stop screw hole. 16. Install air cleaner and adapter. 17. Reset IAC valve. Refer to "Idle Air Control (IAC) System Check." A/C - Refrigerant Recovery/Recycling/Equipment Refrigerant: Technical Service Bulletins A/C - Refrigerant Recovery/Recycling/Equipment Bulletin No.: 08-01-38-001 Date: January 25, 2008 INFORMATION Subject: Information On New GE-48800 CoolTech Refrigerant Recovery/Recharge Equipment Models: 2008 and Prior GM Passenger Cars and Light Duty Trucks (Including Saturn) 2008 and Prior HUMMER H2, H3 2005-2008 Saab 9-7X Attention: This bulletin is being issued to announce the release of GM approved Air Conditioning (A/C) Refrigerant Recovery and Recharging Equipment that meets the new Society of Automotive Engineers (SAE) J2788 Refrigerant Recovery Standards. The ACR2000 (J-43600) cannot be manufactured in its current state after December 2007 and will be superseded by GE-48800. The new J2788 standard does not require that GM Dealers replace their ACR2000 units. ACR2000's currently in use are very capable of servicing today's refrigerant systems when used correctly and can continue to be used. Details regarding the new SAE J2788 standard are outlined in GM Bulletin 07-01-38-004. Effective February 1 2008, new A/C Refrigerant Recovery/Recharging equipment (P/N GE-48800) will be released as a required replacement for the previously essential ACR2000 (J-43600). This equipment is SAE J2788 compliant and meets GM requirements for A/C Refrigerant System Repairs on all General Motors vehicles, including Hybrid systems with Polyolester (POE) refrigerant oil. This equipment will not be shipped as an essential tool to GM Dealerships. In addition, this equipment is Hybrid compliant and designed to prevent oil cross contamination when servicing Hybrid vehicles with Electric A/C Compressors that use POE refrigerant oil. The ACR2000 (J-43600) will need to be retrofitted with a J-43600-50 (Hose - ACR2000 Oil Flush Loop) to be able to perform Hybrid A/C service work. All Hybrid dealers will receive the J-43600-50, with installation instructions, as a component of the Hybrid essential tool package. Dealerships that do not sell Hybrids, but may need to service Hybrids, can obtain J-43600-50 from SPX Kent Moore. Refer to GM Bulletin 08-01-39-001 for the ACR2000 Hose Flush procedure. The High Voltage (HV) electric A/C compressor used on Two Mode Hybrid vehicles uses a Polyolester (POE) refrigerant oil instead of a Polyalkylene Glycol (PAG) synthetic refrigerant oil. This is due to the better electrical resistance of the POE oil and its ability to provide HV isolation. Failure to flush the hoses before adding refrigerant to a Hybrid vehicle with an electric A/C compressor may result in an unacceptable amount of PAG oil entering the refrigerant system. It may cause a Battery Energy Control Module Hybrid Battery Voltage System Isolation Lost Diagnostic Trouble Code (DTC P1AE7) to be set. Additionally, the A/C system warranty will be voided. Warranty Submission Requirements The Electronically Generated Repair Data (snapshot summary) and printer functions have been eliminated from the GE-48800. The VGA display and temperature probes were eliminated to reduce equipment costs. As a result, effective immediately the 18 digit "Snapshot/Charge Summary" code is no longer required for Air Conditioning (A/C) refrigerant system repairs that are submitted for warranty reimbursement. The charge summary data from before and after system repairs will continue to required, but documented on the repair order only. Both high and low pressures and the recovery and charge amounts should be noted during the repair and entered on the repair order. If using ACR2000 (J-43600), the "Snapshot/Charge Summary" printouts should continue to be attached to the shops copy of the repair order. The labor codes that are affected by this requirement are D3000 through D4500. Disclaimer Page 2582 Fan Clutch: Testing and Inspection Engine Overheating 1. Start with cool engine to ensure complete fan clutch disengagement. 2. If fan and clutch assembly free wheels with no drag (revolves more than five times when spun by hand), replace clutch. If clutch performs properly with slight drag, proceed to following step. 3. Position thermometer so it is located between fan blades and radiator, noting the following: a. Insert thermometer sensor through one of existing holes in fan shroud or place between radiator and shroud. It may be necessary to drill a 3/16 inch hole in fan shroud to insert thermometer. b. Check for adequate clearance between fan blades and thermometer sensor before starting engine, as damage could occur. 4. With thermometer in position, cover radiator grill sufficiently to induce high engine temperature. 5. Start engine, then turn on air conditioning and operate at 2000 RPM. 6. Observe thermometer reading when clutch disengages, noting the following: a. It will take approximately five to ten minutes for temperature to become high enough to allow engagement of fan clutch. This will be indicated by a 5-15 degrees F drop in thermometer reading. b. If clutch did not engage between 150-195 degrees F, unit should be replaced. Ensure fan clutch was disengaged at beginning of test. c. If no sharp increase in fan noise or temperature drop was observed and fan noise level was constantly high from start of test to 190 degrees F, unit should be replaced. Do not continue this test past thermometer reading of 190 degrees F to prevent engine overheating. 7. As soon as clutch engages, remove radiator grill cover and turn A/C off to assist in engine cooling. Run engine at approximately 1500 RPM. 8. After several minutes, fan clutch should disengage as indicated by reduction in fan speed and roar. If fan clutch fails to function as described, replace it. Page 1142 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3739 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 2837 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3674 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 451 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3732 Fig.2-Symbols (Part 2 Of 3) Page 1231 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 187 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Diagram Information and Instructions Idle Air Control Valve: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3399 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Component Locations Vehicle Speed Sensor: Component Locations HD Electronic 4-Speed Automatic Overdrive Transmission Page 3217 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3447 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3672 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 783 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3382 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3403 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1251 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1032 Fig.1-Symbols (Part 1 Of 3) Locations Engine Page 3253 Transmission Range Switch (C2) Page 3701 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Locations Keyless Entry Module: Locations Control Module Located in left hand instrument panel sound insulator. Page 2981 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3850 Pinout Description: C1 (Part 2 Of 2) Engine Controls - TBI, C2 Locations Engine Page 482 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 271 Ignition Control Module: Testing and Inspection IC SYSTEM DTC 12 is used during the "On-Board Diagnostic System Check" to test the code display ability of the control module. This DTC indicates that the control module is not receiving the engine rpm (Reference) signal. The "Reference" signal also triggers the fuel injection system. Without the "Reference" signal, the engine cannot operate. RESULTS OF INCORRECT IC OPERATION The control module uses information from the MAP and coolant sensors in addition to rpm to calculate spark advance as follows: - Low MAP output voltage = More spark advance - Cold Engine = More spark advance - High MAP output voltage = Less spark advance - Hot engine = Less spark advance Detonation can be caused by low MAP output or high resistance in the coolant sensor circuit. Poor performance can be caused by high MAP output or low resistance in the coolant sensor circuit. DTC 42 A fault in the IC system will usually set a DTC 42. Refer to DTC 42 in Computers and Controls / System Diagnosis. See: Powertrain Management/Computers and Control Systems/Testing and Inspection When the system is operating on the distributor module, there is no voltage on the bypass line and the module grounds the IC signal. The control module expects to find no voltage on the IC line during this condition. If voltage is found, a DTC 42 will set and the system will not go into the IC mode. When the rpm for IC is obtained (about 400 rpm), the control module applies 5 volts to the bypass line. The IC will no longer be grounded in the module and the IC voltage will be varying. If the bypass line is open, the module will not switch to test mode, so the IC voltage will be low and DTC 42 will be set. If the IC line is grounded, the module will switch to IC, there will be no IC signal and the engine will not operate. A DTC 42 may or may not set. An open in the IC circuit will set a DTC 42 and cause the engine to operate on the distributor module timing. This will cause poor performance and poor fuel economy. To check IC operation, place the vehicle in "Park" or "Neutral" and block the drive wheels. Start the engine and accelerate to 2000 rpm. Note the ignition timing. Disconnect the "Set Timing" connector and again note the timing. The timing will change if the IC system is operating. Page 3016 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1422 - Tighten Control lever nut to 27 Nm (20 lbs. ft). 8. Lower vehicle. 9. Negative battery cable. 10. Check switch for proper operation. Note: The engine must start in the "P" (Park) or "N" (Neutral) positions only. Adjust if needed. Page 3218 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 78 Cruise Control Module: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3237 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1700 Drive Belt: Service and Repair DRIVE BELT REPLACEMENT REMOVE CAUTION: Do not rotate the tensioner except as noted above. Also, do not allow the tensioner to snap into the "free" position. Either of these conditions could damage the belt and/or tensioner. 1. Use a 1/2 inch breaker bar with a socket placed on the pulley axis bolt to rotate the tensioner clockwise and release tension. 2. Belt. INSTALL 1. Route belt over all of the pulleys except the belt tensioner. 2. Use a 1/2 inch breaker bar with socket placed on the tensioner pulley axis bolt and rotate the tensioner to the released position. 3. Belt over tensioner pulley. Slowly allow tensioner to move back into installed position. 4. Check the belt for correct "V" groove tracking into each pulley. Page 2020 Refer to the appropriate section of SI for specifications and repair procedures that are related to the vibration concern. Disclaimer Page 308 Page 933 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2585 Fan Clutch: Service and Repair To prevent silicone fluid from draining into fan drive bearing, do not store or place drive unit on bench with rear of shaft pointing downward. The coil spring type fan clutch cannot be disassembled, serviced or repaired. If it does not function properly, it must be replaced with a new unit. To replace the fan clutch, use the following procedure: 1. Remove the radiator fan shroud. 2. Unfasten the unit from the water pump, then remove the assembly from vehicle. 3. Separate fan from fan clutch. 4. Reverse procedure to install, noting the following: a. Ensure mating surfaces of water pump hub and fan clutch hub are smooth and free of any burrs. b. Align yellow reference marks on water pump hub and fan clutch hub. c. Torque nuts to 18 ft. lbs. Page 2506 Coolant: Technical Service Bulletins Engine Coolant - Information on Back Service File In Section: 6 - Engine Bulletin No: 53-62-02 Date: November, 1995 Subject: DEX-COOL(TM) Engine Coolant - Information on Back service Models: 1994-95 Passenger Cars and Trucks A new extended-life engine coolant called DEX-COOL(TM) is currently being used in all General Motors' vehicles (excluding Chevrolet Geo and Saturn). Refer to bulletin 53-62-01 for general service information. Backservice DEX-COOL(TM) may be used in General Motors vehicles originally built with conventional (green) coolant with the following considerations: ^ Vehicles eligible for back service are 1994 and 1995 models (excluding 1994 J Body with 4 cylinder engines). ^ The service interval for DEX-COOL(TM) introduced into an older model vehicle originally built with "green" coolant will be 2 years/30,000 miles (50,000 Km) (not 5 years/100,000 miles (160,000 Km)). ^ All the "green" coolant must be removed from the cooling system by means of a system flush. This may be accomplished with a water flushing device or a GMDE waterless coolant changer (use a unit dedicated to "green" coolant, not DEX-COOL TM). Important: When using a GMDE waterless coolant changer, conduct the procedure twice, once with water, and once with DEX-COOL(TM) Backservice with DEX-COOL(TM) is advocated because of enhanced water pump seal durability experienced with this coolant. Engine - Noise, Updated Exhaust Manifolds Exhaust Manifold: Customer Interest Engine - Noise, Updated Exhaust Manifolds File In Section: 6 - Engine Bulletin No.: 37-66-02B Date: November, 1996 Subject: Engine Noise (Replace with New Design Cast Iron Exhaust Manifold and Stainless Steel Gasket) Models: 1982-95 Chevrolet and GMC C/K, R/V, G, P Models with 7.4L Engine (VIN N - RPO L19) and Cast Iron Exhaust Manifolds This bulletin is being revised to update the correction information statement and additional service parts information listed under all models. Please discard Corporate Bulletin Number 37-66-02A (Section 6 - Engine). Important: This bulletin does not apply to engines with stainless steel exhaust manifolds (Option H5D). Condition Some owners may comment on an engine noise. The noise is normally loudest when the engine is cold. Cause An exhaust leak may have developed between the cast iron exhaust manifold and the cylinder head mating surface. The cast iron exhaust manifold has warped at the ends. Correction A new exhaust manifold, stainless steel gasket and attaching hardware has been developed to correct this condition. Replace the existing cast iron exhaust manifold and gasket with the new design exhaust manifold, stainless steel gasket and new attaching hardware. Discard the existing hardware since it will not be reused. Page 1477 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 430 TCC/Stoplamp Switch Wiring Page 2995 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 2927 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1877 Refrigerant: Description and Operation PURPOSE Like the coolant in the engine cooling system, the refrigerant is the substance in the air conditioning system that absorbs, carries, and then releases heat. Although various substances are used as refrigerants in other types of refrigeration systems, some automotive air conditioning systems use a type called Refrigerant-12 (R-12). This vehicle uses Refrigerant-134a (R-134a). It is a non-toxic1 non-flammable, clear, colorless liquefied gas. While the R-134a A/C system is very similar to an, R-12 A/C system, the differences in the refrigerant, lubricants, and service equipment are important. NOTICE:R-134a refrigerant is not compatible with R-12 refrigerant in an air conditioning system. R-12 in a R-134a system will cause compressor failure, refrigerant oil sludge or poor air conditioning system performance. Refrigerant-134a carries a charge of a special lubricant called polyalkaline glycol (PAG) refrigerant oil. GM (PAG) refrigerant oil has a slight blue tint. The oil is hydroscopic (absorbs water from the atmosphere). Store it in closed containers. Page 1508 Pressure Switch Assembly Page 98 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1996 1. Use a proper hand reamer, carbide cutter or drill bit to ream the puncture channel from the inside of the tire in order to clean the injury. 2. Remove steel wires protruding above the liner surface to prevent damage to the repair unit. 3. Consult your repair material supplier for recommended reaming tool(s). Fill the Injury 1. It is necessary to fill the injury channel to provide back up for the repair unit and to prevent moisture from entering the tire fabric and steel wires. 2. (For combination repair/plug units skip this step.) Cement the injured channel and fill the injury from the inside of the tire with the repair plug per repair material manufacturer's recommendations. Without stretching the plug, cut the plug off just above the inside tire surface. 3. Consult your repair material supplier for proper repair material selection. Repair Unit Selection Important Do not install the repair unit in this step. Page 2485 Spark Plug: Service and Repair REMOVE OR DISCONNECT Make sure the ignition switch is "OFF." CAUTION: Twist the spark plug boot one-half turn to release It. Pull on the spark plug boot only. Do not pull on the wire or the spark plug lead may be damaged. 1. Spark plug wires and boots. - Label the plug wires. NOTE: These spark plugs have a ceramic Insulator that Is about 1/8 Inch longer than earlier model spark plugs. Be sure to use a spark plug socket that Is deep enough for this longer length spark plug. Failure to do so could cause cracking of the Insulator and arcing In side the spark plug, resulting in engine miss. 2. Spark plugs using a 5/8-inch socket. Inspect Each spark plug for wear and gap. Refer to Testing and Inspection. Spark plugs should be gapped to 0.035 inch. INSTALL OR CONNECT CAUTION: Make sure each plug threads smoothly Into the cylinder head and is fully seated. Cross-threading or failing to fully seat spark plugs can cause overheating of the spark plugs, exhaust blow-by, or thread damage. 1. Spark plugs. Tighten Spark plugs to 15 Nm (11 lbs. ft.). 2. Wire and boot assemblies. Refer to Ignition Cable / Service and Repair for precautions. Page 3943 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 1330 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3362 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3234 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Electrical - Aftermarket Fuse Warning Fuse: Technical Service Bulletins Electrical - Aftermarket Fuse Warning Bulletin No.: 07-08-45-002 Date: September 05, 2007 ADVANCED SERVICE INFORMATION Subject: Service Alert: Concerns With Aftermarket Fuses in GM Vehicles Models: 2008 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2008 and Prior HUMMER H2, H3 2008 and Prior Saab 9-7X Concerns with Harbor Freight Tools "Storehouse" Branded Blade Type Fuses General Motors has become aware of a fuse recall by Harbor Freight Tools/Storehouse for a variety of aftermarket fuses. In two cases, these fuses have not provided protection for the wiring system of the vehicles they were customer installed in. Upon testing the 15 amp version, it was found that the fuse still would not "open" when shorted directly across the battery terminals. How to Identify These Fuses Packed in a 120 piece set, the fuse has a translucent, hard plastic, blue body with the amperage stamped into the top. There are no white painted numbers on the fuse to indicate amperage. There are no identifying marks on the fuse to tell who is making it. The fuses are known to be distributed by Harbor Freight Tools but there may be other marketers, and packaging of this style of fuse. It would be prudent to replace these fuses if found in a customers vehicle. Likewise, if wiring overheating is found you should check the fuse panel for the presence of this style of fuse. All GM dealers should use genuine GM fuses on the vehicles they service. You should also encourage the use of GM fuses to your customers to assure they are getting the required electrical system protection. GM has no knowledge of any concerns with other aftermarket fuses. If additional information becomes available, this bulletin will be updated. Disclaimer Page 2785 Parts are currently available from GMSPO. Warranty Information Labor Operation Description Labor Time J0100 Manifold, Exhaust Use published labor RH - Replace operation time J0101 Manifold, Exhaust Use published labor operation LH - Replace time Trouble Code 92. Page 912 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3274 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1817 Contamination Mixing conventional green coolant with DEX-COOL(R) will degrade the service interval from 5 yrs./150,000 miles (240,000 km) to 2 yrs./30,000 miles (50,000 km) if left in the contaminated condition. If contamination occurs, the cooling system must be flushed twice immediately and re-filled with a 50/50 mixture of DEX-COOL(R) and clean water in order to preserve the enhanced properties and extended service interval of DEX-COOL(R). After 5 years/150,000 miles (240,000 km) After 5 yrs/150,000 miles (240,000 km), the coolant should be changed, preferably using a coolant exchanger. If the vehicle was originally equipped with DEX-COOL(R) and has not had problems with contamination from non-DEX-COOL(R) coolants, then the service interval remains the same, and the coolant does not need to be changed for another 5 yrs/150,000 miles (240,000 km) Equipment (Coolant Exchangers) The preferred method of performing coolant replacement is to use a coolant exchanger. A coolant exchanger can replace virtually all of the old coolant with new coolant. Coolant exchangers can be used to perform coolant replacement without spillage, and facilitate easy waste collection. They can also be used to lower the coolant level in a vehicle to allow for less messy servicing of cooling system components. It is recommended that you use a coolant exchanger with a vacuum feature facilitates removing trapped air from the cooling system. This is a substantial time savings over repeatedly thermo cycling the vehicle and topping-off the radiator. The vacuum feature also allows venting of a hot system to relieve system pressure. Approved coolant exchangers are available through the GMDE (General Motors Dealer Equipment) program. For refilling a cooling system that has been partially or fully drained for repairs other than coolant replacement, the Vac-N-Fill Coolant Refill Tool (GE-47716) is recommended to facilitate removal of trapped air from the cooling system during refill. Disclaimer Page 2939 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 1269 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 751 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1103 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Diagram Information and Instructions Crankshaft Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 2742 Heater And A/C Control Select SW (C2), Stop Lamp & TCC Switch Jumper, Aux Fan Control SW Page 687 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 514 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 2615 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3441 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Locations Cargo Lamp Switch Wiring Base Idle Speed Idle Speed: Specifications Base Idle Speed Transmission Gear Engine Speed [1] OPEN/CLOSED Loop [2] Manual N 625 +/- 25 CL Automatic D 625 +/- 25 CL [1] If the engine has less than 500 miles or is checked at altitudes above 1500 feet, the idle rpm with a seated IAC valve should be lower than above values. [2] Let engine idle until proper fuel control status (OPEN/CLOSED loop) is reached. Page 3790 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 184 Engine Control Module: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3735 Crankshaft Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1997 1. Center the repair unit over the injury as a reference and outline an area larger than the unit so that buffing will not remove the crayon marks. 2. Remove the repair unit. 3. DO NOT overlap previous or multiple repair units. 4. Consult your repair material supplier for proper repair unit selection. Buffing 1. To prevent contamination and preserve the outline, buff within the marked area thoroughly and evenly with a low speed buffing tool using a fine wire brush or gritted rasp. 2. Buff to a smooth velvet surface (RMA #1 or #2 buffed texture). 3. Use caution not to gouge the inner liner or expose casing fabric. 4. Remove any buffing dust with a vacuum cleaner. 5. Consult your repair material supplier for a proper buffing tool. Cementing Apply chemical cement according to the repair material manufacturer's procedures. Repair Unit Application Page 3496 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3669 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3747 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1117 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3825 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 1236 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Locations Powertrain Control Module (PCM) Page 3872 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3748 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3265 HD Electronic 4-Speed Automatic Overdrive Transmission HD 5-Speed Manual Transmission Page 855 Crankshaft Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 2972 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 74 Fig.1-Symbols (Part 1 Of 3) OnStar(R) - Aftermarket Device Interference Information Emergency Contact Module: Technical Service Bulletins OnStar(R) - Aftermarket Device Interference Information INFORMATION Bulletin No.: 08-08-46-004 Date: August 14, 2008 Subject: Information on Aftermarket Device Interference with OnStar(R) Diagnostic Services Models: 2009 and Prior GM Passenger Car and Truck (including Saturn) 2009 and Prior HUMMER H2, H3 Models 2009 and Prior Saab 9-7X with OnStar(R) (RPO UE1) This bulletin is being issued to provide dealer service personnel with information regarding aftermarket devices connected to the Diagnostic Link Connector (DLC) and the impact to OnStar(R) diagnostic probes and Vehicle Diagnostic e-mails. Certain aftermarket devices, when connected to the Diagnostic Link Connector, such as, but not limited to, Scan Tools, Trip Computers, Fuel Economy Analyzers and Insurance Tracking Devices, interfere with OnStar's ability to perform a diagnostic probe when requested (via a blue button call) by a subscriber. These devices also prohibit the ability to gather diagnostic and tire pressure data for a subscriber's scheduled OnStar(R) Vehicle Diagnostic (OVD) e-mail. These aftermarket devices utilize the Vehicles serial data bus to perform data requests and/or information gathering. When these devices are requesting data, OnStar(R) is designed not to interfere with any data request being made by these devices as required by OBD II regulations. The OnStar(R) advisor is unable to definitively detect the presence of these devices and will only be able to inform the caller or requester of the unsuccessful or incomplete probe and may in some cases refer the subscriber/requester to take the vehicle to a dealer for diagnosis of the concern. When performing a diagnostic check for an unsuccessful or incomplete OnStar(R) diagnostic probe, or for concerns regarding completeness of the OnStar(R) Vehicle Diagnostic (OVD) e-mail, verify that an aftermarket device was not present at the time of the requested probe. Regarding the OVD e-mail, if an aftermarket device is interfering (including a Scan Tool of any type), the e-mail will consistently display a "yellow" indication in diagnostics section for all vehicle systems except the OnStar(R) System and Tire Pressure data (not available on all vehicles) will not be displayed (i.e. section is collapsed). Successful diagnostic probes and complete OVD e-mails will resume following the removal or disconnecting of the off-board device. Disclaimer Page 473 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 2752 Temperature Gauge: Testing and Inspection Gauge Reads Low 1. Ensure terminals are clean and connections are tight. 2. Remove lead at sensor, measure resistance using an ohmmeter. 3. At 104 degrees F resistance should be approximately 1200-1350 ohms, and at 125 degrees F resistance should be approximately 53-55 ohms. 4. If resistance is not within specifications, replace sensor. Page 753 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3660 Camshaft Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3809 PCM Connector Pin-Out Page 954 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3772 Data Link Connector: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Wheels/Tires - Tire Radial Force Variation (RFV) Wheels: All Technical Service Bulletins Wheels/Tires - Tire Radial Force Variation (RFV) INFORMATION Bulletin No.: 00-03-10-006F Date: May 04, 2010 Subject: Information on Tire Radial Force Variation (RFV) Models: 2011 and Prior GM Passenger Cars and Light Duty Trucks 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X 2000-2005 Saturn L Series 2003-2007 Saturn ION Supercede: This bulletin is being revised to considerably expand the available information on Radial Force Variation (RFV) and should be reviewed in whole. Please discard Corporate Bulletin Number 00-03-10-006E (Section 03 - Suspension). Important - Before measuring tires on equipment such as the Hunter GSP9700, the vehicle MUST be driven a minimum of 16 km (10 mi) to ensure removal of any flat-spotting. Refer to Corporate Bulletin Number 03-03-10-007E - Tire/Wheel Characteristics of GM Original Equipment Tires. - Equipment such as the Hunter GSP9700 MUST be calibrated prior to measuring tire/wheel assemblies for each vehicle. The purpose of this bulletin is to provide guidance to GM dealers when using tire force variation measurement equipment, such as the Hunter GSP9700. This type of equipment can be a valuable tool in diagnosing vehicle ride concerns. The most common ride concern involving tire radial force variation is highway speed shake on smooth roads. Tire related smooth road highway speed shake can be caused by three conditions: imbalance, out of round and tire force variation. These three conditions are not necessarily related. All three conditions must be addressed. Imbalance is normally addressed first, because it is the simpler of the three to correct. Off-vehicle, two plane dynamic wheel balancers are readily available and can accurately correct any imbalance. Balancer calibration and maintenance, proper attachment of the wheel to the balancer, and proper balance weights, are all factors required for a quality balance. However, a perfectly balanced tire/wheel assembly can still be "oval shaped" and cause a vibration. Before balancing, perform the following procedures. Tire and Wheel Diagnosis 1. Set the tire pressure to the placard values. 2. With the vehicle raised, ensure the wheels are centered on the hub by loosening all wheel nuts and hand-tightening all nuts first by hand while shaking the wheel, then torque to specifications using a torque wrench, NOT a torque stick. 3. Visually inspect the tires and the wheels. Inspect for evidence of the following conditions and correct as necessary: - Missing balance weights - Bent rim flange - Irregular tire wear - Incomplete bead seating - Tire irregularities (including pressure settings) - Mud/ice build-up in wheel - Stones in the tire tread - Remove any aftermarket wheels and/or tires and restore vehicle to original condition prior to diagnosing a smooth road shake condition. 4. Road test the vehicle using the Electronic Vibration Analyzer (EVA) essential tool. Drive for a sufficient distance on a known, smooth road surface to duplicate the condition. Determine if the vehicle is sensitive to brake apply. If the brakes are applied lightly and the pulsation felt in the steering wheel increases, refer to the Brakes section of the service manual that deals with brake-induced pulsation. If you can start to hear the vibration as a low boom noise (in addition to feeling it), but cannot see it, the vehicle likely has a first order (one pulse per propshaft revolution) driveline vibration. Driveline first order vibrations are high enough in frequency that most humans can start to hear them at highway speeds, but are too high to be able to be easily seen. These issues can be caused by driveline imbalance or misalignment. If the vehicle exhibits this low boom and the booming pulses in-and-out on a regular basis (like a throbbing), chances are good that the vehicle could have driveline vibration. This type Page 2543 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 869 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 3935 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 2526 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1038 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3074 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2954 Fig.1-Symbols (Part 1 Of 3) Page 1540 Warranty Information Some owners with actuators that are operating as designed (5-30 seconds engagement time) may choose to upgrade to the fast actuator at their own expense. The fast actuator is a new product enhancement and should not be used to replace actuators that are operating as designed. For vehicles repaired under warranty, use: Service Procedure 1. Remove the front differential carrier shield, if equipped. 2. If necessary, clean the axle housing in the area around the existing actuator. Disconnect the actuator's electrical connection at the front axle housing. 3. Remove the front axle actuator by unthreading the actuator from the axle housing. 4. Install the spacer from the wiring kit into the axle tube with the flat side seated against the shift fork. 5. Install the actuator motor and tighten until the shoulder of the actuator seats against the axle tube. Important: If binding occurs before the actuator is seated, remove the actuator and reseat the spacer by pushing on the spacer with a screwdriver. Then reinstall the actuator. On K3 Models with the cast iron axle tube, there may be a casting burr which may contact the edge of the actuator. This should not create a concern and the actuator should seat against the axle tube. If this contact remains a concern, use a die grinder in order to remove the burr. Page 2118 Wheel Bearing: Adjustments Rockwell Full Floating Axle REAR WHEEL BEARINGS ADJUSTMENT Ensure the brakes are completely released and do not drag. Check wheel bearing play by grasping the tire at the top and pulling and pushing back and forth, or by using a pry bar under the tire. If the wheel bearings are properly adjusted, movement of hub or disc will be barely noticeable. If the movement is excessive, adjust the bearings as follows: 1. Raise and support vehicle. 2. Remove axle shaft. 3. Remove retaining nut and lock washer. 4. Using nut wrench tool No. J-25510, or equivalent, torque adjusting nut, with hub rotating, to 50.0 ft. lbs. Ensure bearing surfaces are in contact, then back adjusting nut off 1/8 turn. 5. Install lock washer, the bend tang over flat of adjusting nut. 6. Install retaining nut and torque to 250 ft. lbs. 7. Install axle shaft. Page 3631 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 2732 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 277 Page 776 Fig.1-Symbols (Part 1 Of 3) Page 183 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3032 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 2525 Fig.2-Symbols (Part 2 Of 3) Service and Repair Position Sensor/Switch: Service and Repair Remove or Disconnect 1. Skid plate (if equipped). 2. Electrical connector from the indicator switch located on the upper right side of the differential. 3. Indicator switch (11). Install or Connect 1. Indicator switch (11). - Coat the switch thread with sealer (GM P/N 1052942) or equivalent. 2. Electrical connector. 3. Skid plate (if equipped). Page 2088 longer. Important Whenever a wheel is refinished, the mounting surface and the wheel nut contact surfaces must not be painted or clearcoated. Coating these surfaces could affect the wheel nut torque. When re-mounting a tire on an aluminum wheel, coated balance weights must be used in order to reduce the chance of future cosmetic damage. Disclaimer Specifications Piston: Specifications Engine Liter/CID .................................................................................................................................. ........................................................... 7.4L/V8-454 All specifications given in inches. Piston Diameter (Std.) [01] .................................................................................................................. ......................................................... 4.2465-4.2485 Piston Clearance ............................................... ............................................................................................................................................ 0.0030-0.0042 Piston Pin Diameter (Std.) ........................................................................................... ................................................................................. 0.9894-0.9897 Pin To Piston Bore Clearance ... .............................................................................................................................................................. ..... 0.0002-0.0007 Piston Rings End Gap [02] Comp. .................................................................................................................................................. .................................................................. [18] Oil .............................................................................. ........................................................................................................................................... 0.01 Side Clearance Comp. .................................................................................................................................................. ................................................. 0.0012-0.0029 Oil .............................................................................. ......................................................................................................................................... 0.005 [01] Measured at 90 deg. angle to piston pin. [02] Minimum. [18] Top, 0.010-0.018 inch; second, 0.016-0.024 inch. Page 3794 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1194 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3385 TP Sensor Circuit Page 1110 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3436 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3820 Fig.1-Symbols (Part 1 Of 3) Page 1201 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2259 - Support the GM Oil Life System, thereby minimizing the replacement of engine oil, before its life has been depleted. - Reduce the duplication of requirements for a large number of internal GM engine oil specifications. International Lubricants Standardization and Approval Committee (ILSAC) GF-5 Standard In addition to GM dexos 1(TM), a new International Lubricants Standardization and Approval Committee (ILSAC) standard called GF-5, was introduced in October 2010. - There will be a corresponding API category, called: SN Resource Conserving. The current GF-4 standard was put in place in 2004 and will become obsolete in October 2011. Similar to dexos 1(TM), the GF-5 standard will use a new fuel economy test, Sequence VID, which demands a statistically significant increase in fuel economy versus the Sequence VIB test that was used for GF-4. - It is expected that all dexos 1(TM) approved oils will be capable of meeting the GF-5 standard. However, not all GF-5 engine oils will be capable of meeting the dexos 1(TM) specification. - Like dexos(TM), the new ILSAC GF-5 standard will call for more sophisticated additives. The API will begin licensing marketers during October 2010, to produce and distribute GF-5 certified products, which are expected to include SAE 0W-20, 0W-30, 5W-20, 5W-30 and 10W-30 oils. Corporate Average Fuel Economy (CAFE) Requirements Effect on Fuel Economy Since CAFE standards were first introduced in 1974, the fuel economy of cars has more than doubled, while the fuel economy of light trucks has increased by more than 50 percent. Proposed CAFE standards call for a continuation of increased fuel economy in new cars and trucks. To meet these future requirements, all aspects of vehicle operation are being looked at more critically than ever before. New technology being introduced in GM vehicles designed to increase vehicle efficiency and fuel economy include direct injection, cam phasing, turbocharging and active fuel management (AFM). The demands of these new technologies on engine oil also are taken into consideration when determining new oil specifications. AFM for example can help to achieve improved fuel economy. However alternately deactivating and activating the cylinders by not allowing the intake and exhaust valves to open contributes to additional stress on the engine oil. Another industry trend for meeting tough fuel economy mandates has been a shift toward lower viscosity oils. dexos 1(TM) will eventually be offered in several viscosity grades in accordance with engine needs: SAE 0W-20, 5W-20, 0W-30 and 5W-30. Using the right viscosity grade oil is critical for proper engine performance. Always refer to the Maintenance section of a vehicle Owner Manual for the proper viscosity grade for the engine being serviced. GM Oil Life System in Conjunction With dexos (TM) Supports Extended Oil Change Intervals To help conserve oil while maintaining engine protection, many GM vehicles are equipped with the GM Oil Life System. This system can provide oil change intervals that exceed the traditional 3,000 mile (4,830 km) recommendation. The dexos (TM) specification, with its requirements for improved oil robustness, compliments the GM Oil Life System by supporting extended oil change intervals over the lifetime of a vehicle. If all GM customers with GM Oil Life System equipped vehicles would use the system as intended, GM estimates that more than 100 million gallons of oil could be saved annually. GM dexos 2(TM) Information Center Website Refer to the following General Motors website for dexos 2(TM) information about the different licensed brands that are currently available: http://www.gmdexos.com GM dexos 2(TM) Engine Oil Trademark and Icons Page 2718 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 217 Idle/Throttle Speed Control Unit: Adjustments Idle Speed Control Actuator Adjustment Procedure: - Before adjusting ISC actuator you must first check the minimum idle speed to be within specifications. Refer to SPECIFICATIONS/IDLE SPEED. (ISC actuator must have vacuum applied so that it is not contacting the throttle lever.) See image VIEW A. - Remove vacuum hose on ISC actuator on warm engine. - Adjust ISC actuated idle speed to 1300 +/- 50 rpm. See image VIEW B. - Install vacuum hose. Page 1562 This relay incorporates a 5 second delay for the front axle to engage in order to allow the transfer case synchronizer to energize. For 88-93 vehicles, if the axle has to be replaced, use jumper harness P/N 15313272. CKT 1695 (BLK/WHT) fits into cavity A of the fast actuator. The circuit includes the cable seal and the terminal pin. This circuit plugs into the 5-pin axle actuator connector. 11. Do the following steps in order to install jumper harness P/N 15313272: a. Locate the axle actuator 5-pin connector on the service actuator wiring harness and remove the TPA. b. Remove and discard the cavity plug from cavity A. c. Install CKT 1695 lead (BLK/WHT) from the jumper harness that has the cable seal and terminal into axle actuator connector cavity A. d. Reinstall the TPA on the 5-pin connector. e. Install the service actuator harness 5-pin connector into the axle actuator. f. Connect jumper harness 2x2 connector into the existing vehicle 4WD mating connector. g. Strap the jumper harness and the service harness to the tab on the axle tube. Locations Underhood Fuse/Relay Center Page 2930 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 664 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3920 Serial Data: Component Tests and General Diagnostics A Scan Tool can be connected to the Data Link Connector (DLC), this allows the Scan Tool to communicate with either the Powertrain Control Module (PCM) or the Diagnostic Energy Reserve Module (DERM). System operations can then be monitored for diagnostic purposes. There is one data lines access with a Scan Tool. circuit 800 (TAN) data line allows the Powertrain Control Module and the Diagnostic Energy Reserve Module to communicate with each other and/or a Scan Tool. Engine, A/T - Shift/Driveability Concerns/MIL ON Air Filter Element: Customer Interest Engine, A/T - Shift/Driveability Concerns/MIL ON Bulletin No.: 04-07-30-013B Date: February 01, 2007 INFORMATION Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007 HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X Supercede: This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 04-07-30-013A (Section 07 - Transmission/Transaxle). The use of an excessively/over-oiled aftermarket, reusable air filter may result in: Service Engine Soon (SES) light on Transmission shift concerns, slipping and damaged clutch(es) or band(s) Engine driveability concerns, poor acceleration from a stop, limited engine RPM range The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur. When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared to a like vehicle with an OEM air box and filter under the same driving conditions to verify the concern. The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty. If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and the air induction hose for contamination of oil prior to making warranty repairs. Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not considered to be warrantable repair items. Page 2193 EXAMPLE 2: The lower insert is stamped STD (standard) and the upper is stamped 0.0010". The undersize for a STD bearing is 0. Divide 0 by 2 to get 0. Divide 0.0010" by 2 to get 0.0005". Add 0 and 0.0005" together to calculate the bearing undersize, which is 0.0005" in this case. 13. Add the original bearing undersize calculated in step 12 to the clearance measured and written down in step 9. For example, if a clearance of 0.0030" was measured with plastigage in step 9 and the calculated bearing undersize from step 12 was 0.0005", the bearing clearance for that particular main journal is equal to 0.0030" plus 0.0005". The bearing clearance would be 0.0035" in this case. 14. Determine which of the combinations of two sizes of replacement bearings will produce the desired clearance. The two sizes available are 0.001" and 0.002". One insert of each size may be combined to produce an intermediate undersize of 0.0015". Subtract the replacement bearing size from the actual clearance to determine which bearing should be used. The bearing that should be used is the one which gives a clearance closer to 0.0008" than to 0.0028". The clearance must not be less than 0.0008". Using the example from step 11, the actual clearance is 0.0035". Subtracting 0.001" from 0.0035" will give a clearance of 0.0025", just barely within the required range. Subtracting 0.002" from 0.0035" will give a clearance of 0.0015". The 0.002" undersize bearing set would be the one to use in this case since it gives a clearance closer to 0.0008", but not less. 15. Install the replacement upper main bearing insert using tool J 8080. 16. Install the replacement lower main bearing insert in the main bearing cap. Lay a piece of plastigage across the width of the lower main bearing insert (same as step 5). 17. Repeat steps 7, 8 and 9. 18. Measuring the plastigage with the scale on the envelope, verify the clearance of the replacement bearings is within the range of 0.001" to 0.003". 19. Repeat steps 4 through 16 for each main bearing. 20. Thrust the crankshaft forward and backward several times to seat the thrust bearing. 21. Reinstall oil pump; torque to 88 N.m (65 lb ft). 22. Reinstall the oil pan and other hardware. 23. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 24. Install fuel pump fuse, start engine, check for leaks or unusual noises. 25. Road test vehicle, check for leaks or unusual noises. THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE OUT OF THE VEHICLE Recommended for K, S and T vehicles. 1. Remove the engine from the vehicle using the appropriate service manual procedure. 2. Mount the engine on an engine stand, flip the engine so the oil pan is facing up. 3. Remove the oil pan. 4. Remove the oil pump and shield. 5. Remove the dipstick tube. 6. Remove one (1) main bearing cap (must do one at a time). 7. Plasti-gage bearing. 8. If the bearing clearance is out of specification (clearance greater than 0.003 inches), remove upper main bearing from the block. 9. Check the size of the original bearing. 10. Determine what combination of new bearings are required to get the clearance in the acceptable range of 0.0008 inches to 0.0028 inches. See steps Page 3302 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 2658 - If replacing hose, remove retainer from hose and reinsert in connector. - If reusing hose and connector, retainer can remain in place on hose. Install or Connect 1. Push hose into connector until retainer tabs lock. Pull back on hose to check for proper engagement. 2. Inlet hose to heater core. 3. Inlet hose clamp. 4. Inlet hose mounting screw. Tighten screw to 1.4 Nm (12 lbs. in.). 5. Engine coolant. 6. Air cleaner. - Check the system for leaks. Page 718 Rear Door Jamb Switch Wiring Page 974 1994 G VAN 3A-7O Page 1021 Oxygen Sensor: Testing and Inspection VISUAL INSPECTION: - Connectors and wires - Housing and insulator for cracks/damage - Sensor tip for silicone contamination (white powdery coating) PERFORMANCE TEST: Checks working range and response (speed). - Warm engine - Install DVOM between sensor and ground (2 volt D.C. range) - "RUN" engine at steady cruise speed (about 2500 rpm) Voltage should vary at least eight times in ten seconds between 0.2 and 0.8 volts (normal range). - Drive system rich: The use of a properly adjusted propane flow-meter (J-26911) is industry standard. Voltage should increase to at least 0.8 volts within two to three seconds. - Drive system lean: Create a vacuum leak from a source that is not an ECM input or output. Voltage should drop to at least 0.3 volts within two to three seconds. NOTE: After each test the O2 sensor should return to normal operating range within two to three seconds. - O2 Sensor should be replaced for failure to pass any of the tests above. NOTE: A CEC system that is operating excessively rich or lean will drive the 02 sensor to its maximum range and should be repaired first and not diagnosed as a 02 sensor failure. - Reconnect all hoses and electrical connectors. Clear all codes set and retrain idle. Page 546 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 2595 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2809 PCM Connector Pin-Out Page 3226 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1015 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 1544 ^ For 1993 and prior vehicles, splice into CKT 50 (BRN) between connector C152 and GT101 (Figures 2, 3, 4). Page 2277 12 through 14 in the "in-vehicle" service outlined above. 11. Reinstall the upper main bearing. 12. Reinstall the main cap and lower bearing; torque to 110 N.m (80 lb ft). 13. Repeat for each main bearing. 14. Reinstall oil pump and shield; torque to 88 N.m (65 lb ft). 15. Reinstall dipstick tube. 16. Reinstall oil pan. 17. Reinstall engine in vehicle. 18. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 19. Install fuel pump fuse, start engine, check for leaks or unusual noises. 20. Road test vehicle, check for leaks or unusual noises. Correction Category B: Valve Train Clatter, Tick or Click For 1992-94 vehicles equipped with a 4.3L V6 (LB4 VIN Z or L35 VIN W) engine see Corporate Bulletin 376006 for information on converting from net lash to adjustable lash and/or re-lashing the valves on an adjustable lash system. Investigation of "cold knock" is continuing. Updates will continue to be provided when available. Parts Information Check-Valve Filters Description Part Number V6, V8 (Four-Wheel Drive) FRAM PH3980 12555891 V8 (Two-Wheel Drive), Mark V8 PF1218 25160561 The FRAM PH3980 is to be used in place of the PF52. The PH3980 provides superior anti-drainback performance, a key factor in reducing cold knock. FRAM filters are to be procured locally until 08-15-95. After this date the filters may be ordered from GMSPO using the supplied part number. Orders placed to GMSPO prior to this date will not be placed on backorder. Bearings Description Part Number 0.001" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 10120992 0.001" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 10120994 0.002" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 12329758 0.002" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 12329792 Main bearing kits are currently available from GMSPO. All calibrations are currently available from GMSPO. Page 3311 Fig.1-Symbols (Part 1 Of 3) Page 1818 Coolant: Technical Service Bulletins Engine Coolant - Information on Back Service File In Section: 6 - Engine Bulletin No: 53-62-02 Date: November, 1995 Subject: DEX-COOL(TM) Engine Coolant - Information on Back service Models: 1994-95 Passenger Cars and Trucks A new extended-life engine coolant called DEX-COOL(TM) is currently being used in all General Motors' vehicles (excluding Chevrolet Geo and Saturn). Refer to bulletin 53-62-01 for general service information. Backservice DEX-COOL(TM) may be used in General Motors vehicles originally built with conventional (green) coolant with the following considerations: ^ Vehicles eligible for back service are 1994 and 1995 models (excluding 1994 J Body with 4 cylinder engines). ^ The service interval for DEX-COOL(TM) introduced into an older model vehicle originally built with "green" coolant will be 2 years/30,000 miles (50,000 Km) (not 5 years/100,000 miles (160,000 Km)). ^ All the "green" coolant must be removed from the cooling system by means of a system flush. This may be accomplished with a water flushing device or a GMDE waterless coolant changer (use a unit dedicated to "green" coolant, not DEX-COOL TM). Important: When using a GMDE waterless coolant changer, conduct the procedure twice, once with water, and once with DEX-COOL(TM) Backservice with DEX-COOL(TM) is advocated because of enhanced water pump seal durability experienced with this coolant. Page 3087 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 2520 Forward Lamps Harness, RH Side Locations Convenience Center Page 311 Page 1150 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 205 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 1432 Fig.1-Symbols (Part 1 Of 3) Page 2375 Oil Pressure Gauge: Testing and Inspection Gauge Reads Low 1. Check oil level, add if necessary. 2. Turn ignition switch to the On position. 3. Remove oil pressure sensor lead at sensor, gauge should read high. 4. If gauge stays low, remove sensor lead at gauge. Gauge should read high. If gauge reads high, locate and repair short to ground between gauge and sensor. 5. If gauge still reads low, replace cluster. 6. With lead removed at sensor, connect an ohmmeter to sensor. With engine stopped resistance should be one ohm, and approximately 44 ohms with engine running. 7. If sensor reads significantly lower than 44 ohms with engine running, replace sensor. Page 2557 Radiator Cooling Fan Motor: Symptom Related Diagnostic Procedures Auxiliary Cooling Fan Does Not Operate (Part 1 Of 2) Diagram Information and Instructions Cruise Control Module: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 821 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 650 HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Diagrams Idle Air Control Valve, Dist.ignition Control Module Page 1921 I/P Fuse Block Page 2948 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 413 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 398 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 1380 4. Locate the surface for the cylinder release button on the plastic ignition switch housing and center punch a location on the "rib" approximately 3/8" rearward (toward the key entry end) from the cylinder release button, see Figure 3. 5. Using a 1/8" drill bit, carefully drill a pilot hole through the plastic housing only. 6. Using a 9/32" drill bit, carefully drill a larger hole at the pilot location, and slightly into the lock cylinder surface to break the release button retaining spring. 7. Remove portions of the broken spring from the hole using a small pair of needle nose pliers (or other suitable tool) and turn switch over to shake out the release button. 8. Grasp the lock cylinder, remove it from the switch housing. 9. Remove any plastic "flash" from the drilling operations and, using compressed air, blow out the ignition switch assembly. 10. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 11. Install the new cylinder(s) as required by rotating both the cylinder and ignition switch to the "ON" position and pushing the cylinder into the switch. It may be necessary to depress the release button slightly as it passes by the 9/32" hole previously drilled in the housing. 12. Reassemble the ignition switch and instrument panel components as indicated by the appropriate Service Manual. Stop Lamp Relay - Updated Part Brake Lamp Relay: Technical Service Bulletins Stop Lamp Relay - Updated Part File In Section: 8 - Chassis/Body Electrical Bulletin No.: 56-82-07 Date: November, 1995 Subject: Replacement of Stop Lamp Relay Models: 1995 Chevrolet and GMC Truck C/K Pickup, Extended Cab, Crew Cab Models When replacing the stop lamp relay (Part # 12088592), the following updated part with improved contact surfaces should be used: Parts Information P/N Description Quantity 12135175 Stop Lamp Relay 1 Parts are currently available from GMSPO. Warranty Information For vehicles repaired under warranty, use: Labor Operation Labor Time N2913 0.2 hr Page 1221 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Service and Repair Malfunction Indicator Lamp: Service and Repair The CHECK ENGINE LAMP will be illuminated when the ignition switch is placed in the "ON" position. When the engine is started, the lamp should turn "OFF". If the lamp remains "ON" for 10 seconds or constantly after the engine is started, the self diagnosis system has detected a problem and has stored a code in the system Control Module. After diagnosis and repair, the ECM memory can be cleared of codes by removing the Control Module fuse or disconnecting the battery ground cable for approximately 30 seconds, with ignition switch in the "OFF" position. NOTE If battery ground cable is disconnected to clear codes, components such as clocks, electronically tuned radios etc., will have to be reset. - It is a good idea to record preset radio stations before disconnecting the negative battery cable. This will allow the stations to be reset as to not inconvenience the customer. Page 1190 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 1389 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2733 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1872 Refrigerant: Technical Service Bulletins A/C - R134a Leak Detection With Tracer Dye File In Section: 1 - HVAC Bulletin No.: 43-12-15 Date: November, 1994 Subject: R134a Leak Detection with Tracer Dye Models: All 1993-95 Vehicles with OEM R134a Systems All R12 Vehicles Retrofitted to R134a Systems R134a refrigerant is uniquely different from R12 refrigerant and requires some changes in the repair methods, tools and materials used in A/C service. Two important differences between R134a and R12 which affect the technicians ability to locate refrigerant leaks are: 1. The R134a molecule is smaller than the R12 molecule and therefore will leak through smaller openings. For the same size opening the smaller R134a molecule will leak out faster than the R12. 2. R134a refrigerant does not contain chlorine which the older R12 electronic leak detectors found very easy to identify. Many of today's electronic leak detectors have difficulty locating small R134a refrigerant leaks. In order to insure the highest quality in A/C system service, the J 39400 electronic leak detector was released as an essential tool for all GM dealers. This is the only refrigerant leak detector approved by GM for service on R134a vehicles. If maintained properly (Reference Bulletin No. 431218) and used in accordance with Service Manual procedures, the J 39400 will provide the most accurate and efficient method of locating R134a refrigerant leaks under most conditions. If the technician cannot find the leak with the J 39400 and the system is known to have lost charge, a new fluorescent leak tracer dye Kent-Moore* P/N J 41447, has been released that mixes with the R134a PAG oil. This dye is detectable through the use of an ultraviolet (black) light and glows yellow/green at the leak location (similar to using dye in engine leak detection). J 41447 IS THE ONLY APPROVED DYE BY GENERAL MOTORS. Not all R134a dyes are compatible with GM's PAG oil. Some dyes decrease the oil viscosity or chemically react with the oil. Use of alternate products may affect system reliability and cause premature compressor failure. Note: THIS DYE IS NOT TO BE USED IN R-12 SYSTEMS. Unlike mineral oil, the R134a PAG oil has special properties the technician should keep in mind. 1. PAG oil is water soluble and traces of PAG oil found at leaking joints are subject to "washing out". Condensation on refrigerant lines or the evaporator core may wash the PAG oil and leak dye off the line or off the core and out the condensate drain. This can make some leaks harder to find using the dye detector. Fluorescence at the drain opening would indicate a core leak. 2. Use of the R134a tracer dye requires time. Depending upon the leak rate, it may take between 15 minutes and 7 days for the leak to become visible. 3. The dye, mixed with the PAG oil, is retained in the system and is detectable for 2+ years. Do not double or triple charge the system with dye as this may cause reliability concerns. Use only the 1/4 oz. charge. The dye has a refrigerant leak detection notice sticker included with the package. Complete the sticker information and place near the charge label. Dye Injection R-134a dye can be injected two ways: 1. With the A/C system charged, use the instructions provided with the new R134a leak dye injection tool, J 41436. 2. With A/C system discharged, add dye into the newly replaced component assembly. It is important to note that it is normal to find oil traces at the compressor shaft seal during compressor operation, some oil will hydraulically seep past the shaft seal. This does not mean that the shaft seal is defective or that the refrigerant has leaked. Refrigerant leaks at the shaft seal should be verified with the electronic leak detector (J 39400) following the procedure detailed in the Service Manual. If, however, the amount of oil is excessive, the shaft seal is suspect and should be replaced. (For example, refrigerant oil has coated the clutch plate edge at gap between clutch and pulley, or oil slinging has occurred-oil line shows on underside of hood, etc.). Also, after working on A/C components with dye, it is important to wipe the joint and/or access ports clean of any residual dye with GM solvent (GM Page 1089 Electronic 4-Speed Automatic Overdrive Transmission Page 1349 Impact Sensor: Description and Operation Discriminating Sensors There are two discriminating sensors in the air bag system. They are wired in parallel on the low (ground) side of the deployment loop. These sensors are calibrated to close with speed changes severe enough to warrant deployment. A diagnostic resistor is connected in parallel with the switch contacts within each of the discriminating sensors. These parallel resistors supply the ground path for the current passing through the deployment loop during normal operation. This current flow results in voltage drops across each component in the deployment loop. The DERM monitors these voltage drops to detect malfunctions. Page 256 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 950 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Starting - Revised Procedures for Inop Ignition Cylinder Technical Service Bulletin # 73-01-09 Date: 971001 Starting - Revised Procedures for Inop Ignition Cylinder File In Section: 0 - General Information Bulletin No.: 73-01-09 Date: October, 1997 INFORMATION Subject: New Tumblers for Cylinder Recoding, Revised Repair Procedures for Inoperative Ignition Cylinders (Seized/Won't Rotate), Labor Operation/Time Allowances Models: 1995-97 Buick Skylark, Riviera 1995-97 Chevrolet Cavalier 1997 Chevrolet Corvette, Malibu, Venture 1995-97 Oldsmobile Achieva 1997 Oldsmobile Aurora, Cutlass, Silhouette 1995-97 Pontiac Grand Am, Sunfire 1997 Pontiac Grand Prix, Trans Sport 1995-97 Chevrolet and GMC C/K, S/T Models 1996-97 Chevrolet and GMC G, M/L Vans 1996-97 Oldsmobile Bravada The information in this bulletin concerns new designed tumblers for recoding lock cylinders that use double sided reversible keys, revised procedures for servicing ignition lock cylinders that are seized or not able to rotate and revised labor time guide information and allowances. Parts Information Parts are currently available from GMSPO. Warranty Information Page 1322 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Park/Neutral Position and Backup Lamp Switch Transmission Position Switch/Sensor: Locations Park/Neutral Position and Backup Lamp Switch HD Electronic 4-Speed Automatic Overdrive Transmission Page 1152 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 181 Fig.2-Symbols (Part 2 Of 3) Page 1486 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 449 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 185 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2736 Temp Sensor Circuit Wiring Page 1749 1992 LB4 VIN Z with "cold knock" only 1992-93 LB4 VIN Z with "cold knock" and installed field fix PROM OR with "cold knock" and detonation 1990-95 LB4 VIN Z Install check valve oil filter P/N 12555891 (FRAM PH3980). If the filter does not cure the condition, install the appropriate calibration from the tables (calibrations are available for all 1992 and some 1993 LB4 applications). If a calibration is not offered or does not cure the short duration cold knock Locations Fuel Pump Relay: Locations FUEL PUMP RELAY Underhood Fuse/Relay Center The Fuel Pump Relay is located in Underhood Fuse Relay Center. The Underhood Fuse Relay Center is located on the LH rear of engine compartment, on fender. Page 2219 Valve Clearance: Adjustments These models have a through bolt instead of a stud and adjusting nut. No adjustment is necessary. Page 1449 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 236 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 2815 PCM Connector Pin-Out Capacity Specifications Clutch Fluid: Capacity Specifications Fill the clutch master cylinder to the "Full" or "MAX" mark on the reservoir. Do not overfill. Caution: Should accidental spillage occur, rinse the area thoroughly with water. Pay special attention to any electrical wires, parts, harnesses, rubber or painted surfaces. Page 1893 Brake Bleeding: Service and Repair Master Cylinder Bleeding This procedure can be performed with master cylinder on or off vehicle. 1. Disconnect brake lines at master cylinder, if necessary. 2. Connect suitable lengths of brake lines to master cylinder and immerse other ends of lines in master cylinder reservoirs. 3. Apply master cylinder pushrod or brake pedal with full strokes until air bubbles have disappeared in reservoirs. It may require 20-30 applications to fully eliminate air bubbles. 4. Remove bleeding lines from master cylinder, then install master cylinder on vehicle, if necessary, and connect brake lines. It is not necessary to bleed entire hydraulic system after replacing master cylinder, providing master cylinder has been bled and filled during installation. Page 1327 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 2859 Idle/Throttle Speed Control Unit: Service and Repair Throttle Body Assembly (Model 220) REMOVAL: - Remove the Idle Speed Control (ISC) Actuator and vacuum hose. - Remove ISC Actuator. INSTALLATION: - Install the ISC actuator and screws. - Connect vacuum hose. - Set activated idle speed. Refer to Adjustment Procedures. Page 3376 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Specifications Thermostat: Specifications Radiator Cap Relief Pressure, Lbs. ..................................................................................................... ............................................................................... 15 Thermo. Opening Temp., deg.F ..................... .............................................................................................................................................................. .... 195 Page 2926 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 696 Brake Light Switch: Service and Repair Stop Lamp Switch Remove or Disconnect 1. Negative battery cable. 2. Retainer from brake pedal pin. 3. Switch by unsnapping from pushrod. 4. Electrical connector from switch. Install or Connect 1. Electrical connector into switch. 2. Switch by snapping it onto pushrod. 3. Retainer onto brake pedal pin. 4 Negative battery cable. Page 1301 Ignition Switch Lock Cylinder: Service and Repair The procedure has been updated by TSB# 73-01-09 Important: This new procedure involves drilling a hole through the plastic ignition switch and into the lock cylinder slightly to break or access a cylinder release button retaining spring (similar to G, J and N models). The removal of the broken spring and then the release button will allow the switch to be reused. 1. Remove the necessary trim panels to gain access to the instrument panel mounted switch (refer to information in "Body and Accessories Section, Instrument Panel, Gauges and Consoles"). a. On instrument panel mounted N models (Malibu and Cutlass), the switch and cylinder can be accessed after removing the instrument cluster assembly and positioning the switch/cylinder upward in the cavity for the cluster assembly. b. On Corvette models, the switch and cylinder can be accessed after removing the knee bolster from the lower instrument panel area and positioning the switch/cylinder downward from its location on the instrument panel. 2. Loosen switch from instrument panel and disconnect the electrical connections, BUT NOT the cable connection for BTSI (Brake/Transmission Shift Interlock). 3. Protect the immediate work area with a fender cover or other suitable material. 4. Locate the surface for the cylinder release button on the plastic ignition switch housing and center punch a location on the "rib" approximately 3/8" rearward (toward the key entry end) from the cylinder release button, see Figure 3. 5. Using a 1/8" drill bit, carefully drill a pilot hole through the plastic housing only. 6. Using a 9/32" drill bit, carefully drill a larger hole at the pilot location, and slightly into the lock cylinder surface to break the release button retaining spring. 7. Remove portions of the broken spring from the hole using a small pair of needle nose pliers (or other suitable tool) and turn switch over to shake out the release button. 8. Grasp the lock cylinder, remove it from the switch housing. 9. Remove any plastic "flash" from the drilling operations and, using compressed air, blow out the ignition switch assembly. 10. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 11. Install the new cylinder(s) as required by rotating both the cylinder and ignition switch to the "ON" position and pushing the cylinder into the switch. It may be necessary to depress the release button slightly as it passes by the 9/32" hole previously drilled in the housing. 12. Reassemble the ignition switch and instrument panel components as indicated by the appropriate Service Manual. Page 392 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2829 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1090 VSS Signal Buffer Module - C/K Page 2425 Disclaimer Page 3492 Knock Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 2610 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3822 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 2899 Fuel Pump Relay: Description and Operation OPERATION When the key is first turned "ON" without the engine running, the control module turns a fuel pump relay "ON" for two seconds. This builds up the fuel pressure quickly. If the engine is not started within two seconds, the control module shuts the fuel pump "OFF," and waits for ignition reference pulses. As soon as the engine is cranked, the control module turns the relay "ON" and runs the fuel pump. When the engine is cranking or operating, the control module receives distributor ignition reference pulses which also energize the injectors. As a backup system to the fuel pump relay, the fuel pump is also turned "ON" by an oil pressure switch. When the engine oil pressure reaches about 28 kPa (4 psi), through cranking the oil pressure switch will close to complete the circuit to the fuel pump. An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold. The oil pressure switch will turn "ON" the fuel pump as soon as oil pressure reaches about 28 kPa (4 psi). Page 784 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1390 Fig.1-Symbols (Part 1 Of 3) Description and Operation Coolant Level Indicator Lamp: Description and Operation This system uses a sensor mounted on the radiator and an indicator light mounted in the instrument panel to warn the driver if coolant level is too low. This light is wired in series with the ignition switch, ECM and the sensor. When the ignition switch is turned to the crank position, the circuit is energized and the indicator light will illuminate. When the ignition switch is turned to the ON position and coolant level is sufficient, the sensor will indicate this to the ECM and the light will turn off. Page 908 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Steering/Suspension - Wheel Alignment Specifications Alignment: Technical Service Bulletins Steering/Suspension - Wheel Alignment Specifications WARRANTY ADMINISTRATION Bulletin No.: 05-03-07-009C Date: December 09, 2010 Subject: Wheel Alignment Specifications, Requirements and Recommendations for GM Vehicles Models: 2011 and Prior GM Passenger Cars and Light Duty Trucks Supercede: This bulletin is being extensively revised to provide technicians and warranty administrators with an all inclusive guide for wheel alignments. PLEASE FAMILIARIZE YOURSELF WITH THESE UPDATES BEFORE PERFORMING YOUR NEXT GM WHEEL ALIGNMENT SERVICE. Please discard Corporate Bulletin Number 05-03-07-009B (Section 03 - Suspension). Purpose The purpose of this bulletin is to provide retail, wholesale and fleet personnel with General Motors' warranty service requirements and recommendations for customer concerns related to wheel alignment. For your convenience, this bulletin updates and centralizes all of GM's Standard Wheel Alignment Service Procedures, Policy Guidelines and bulletins on wheel alignment warranty service. Important PLEASE FAMILIARIZE YOURSELF WITH THESE UPDATES BEFORE PERFORMING YOUR NEXT GM WHEEL ALIGNMENT SERVICE. The following five (5) key steps are a summary of this bulletin and are REQUIRED in completing a successful wheel alignment service. 1. Verify the vehicle is in an Original Equipment condition for curb weight, tires, wheels, suspension and steering configurations. Vehicles modified in any of these areas are not covered for wheel alignment warranty. 2. Review the customer concern relative to "Normal Operation" definitions. 3. Verify that vehicle is within the "Mileage Policy" range. 4. Document wheel alignment warranty claims appropriately for labor operations E2000 and E2020. The following information must be documented or attached to the repair order: - Customer concern in detail - What corrected the customer concern? - If a wheel alignment is performed: - Consult SI for proper specifications. - Document the "Before" AND "After" wheel alignment measurements/settings. - Completed "Wheel Alignment Repair Order Questionnaire" (form attached to this bulletin) 5. Use the proper wheel alignment equipment (preferred with print-out capability), process and the appropriate calibration maintenance schedules. Important If it is determined that a wheel alignment is necessary under warranty, use the proper labor code for the repair. E2000 for Steering Wheel Angle and/or Front Toe set or E2020 for Wheel Alignment Check/Adjust includes Caster, Camber and Toe set (Wheel alignment labor time for other component repairs is to be charged to the component that causes a wheel alignment operation.). The following flowchart is to help summarize the information detailed in this bulletin and should be used whenever a wheel alignment is performed. Page 2604 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 695 Brake Light Switch: Adjustments Stop Lamp Switch Remove or Disconnect 1. Negative battery cable. 2. Retainer from brake pedal pin. 3. Switch by unsnapping from pushrod. 4. Electrical connector from switch. Install or Connect 1. Electrical connector into switch. 2. Switch by snapping it onto pushrod. 3. Retainer onto brake pedal pin. 4 Negative battery cable. Page 3371 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1448 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1014 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3571 Timing Mark Page 2805 results from the alteration or modification of a vehicle using non-GM approved parts or accessories. Dealers should be especially cautious of accessory companies that claim the installation of their product will not void the factory warranty. Many times these companies have even given direction on how to quickly disassemble the accessory in an attempt to preclude the manufacturer from finding out that is has been installed. Any suspect repairs should be reviewed by the Fixed Operations Manager (FOM), and in Canada by the Warranty Manager (WM) for appropriate repair direction. If it is decided that a goodwill repair is to be made on the vehicle, even with the installation of such non-GM approved components, the customer is to be made aware of General Motors position on this issue and is to sign the appropriate goodwill documentation required by General Motors. It is imperative for dealers to understand that by installing such devices, they are jeopardizing not only the warranty coverage, but also the performance and reliability of the customer's vehicle. Disclaimer Component Locations Auxiliary Cooling Fan Description and Operation Serial Data: Description and Operation A Scan Tool can be connected to the Data Link Connector (DLC), this allows the Scan Tool to communicate with either the Powertrain Control Module (PCM) or the Diagnostic Energy Reserve Module (DERM). System operations can then be monitored for diagnostic purposes. There is one data lines access with a Scan Tool. circuit 800 (TAN) data line allows the Powertrain Control Module and the Diagnostic Energy Reserve Module to communicate with each other and/or a Scan Tool. Page 3125 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 373 19. Pull back access door on the upper evaporator case carefully to prevent breaking the case (Figure 1). Align the TXV capillary against the evaporator outlet tube being sure not to damage the capillary line. Place the first holding clamp so it is located 1/4" or less below the crimp in the capillary tube (Figure 3). Install the second clamp 1/4" or less below the first clamp. Be sure the clamps are fully seated on the tube and that the capillary is retained in the formed seat of each clamp (Figure 3, Section 1-1). Notice: After all components are installed, evacuate and charge the A/C system. Leak test all joints that were opened. 20. Using a heat gun to soften the plastic case, close both access doors and align the edges of the plastic. Using a soldering gun, melt both edges of the case together along the full length of the cuts, as smoothly as possible. 21. Cover the soldered closures with duct tape to prevent air leakage. 22. Reinstall the right side trim panel, the D-pillar trim, the C-pillar trim, the C-pillar seat belt retainer and the rear bench seat. Page 3275 Fig.1-Symbols (Part 1 Of 3) Page 3723 Temp Sensor Circuit Wiring Page 1254 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Diagrams Knock Sensor Module Page 748 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 1112 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 2723 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Diagram Information and Instructions Coolant Temperature Sensor/Switch (For Computer): Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 235 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 1292 4. Locate the surface for the cylinder release button on the plastic ignition switch housing and center punch a location on the "rib" approximately 3/8" rearward (toward the key entry end) from the cylinder release button, see Figure 3. 5. Using a 1/8" drill bit, carefully drill a pilot hole through the plastic housing only. 6. Using a 9/32" drill bit, carefully drill a larger hole at the pilot location, and slightly into the lock cylinder surface to break the release button retaining spring. 7. Remove portions of the broken spring from the hole using a small pair of needle nose pliers (or other suitable tool) and turn switch over to shake out the release button. 8. Grasp the lock cylinder, remove it from the switch housing. 9. Remove any plastic "flash" from the drilling operations and, using compressed air, blow out the ignition switch assembly. 10. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 11. Install the new cylinder(s) as required by rotating both the cylinder and ignition switch to the "ON" position and pushing the cylinder into the switch. It may be necessary to depress the release button slightly as it passes by the 9/32" hole previously drilled in the housing. 12. Reassemble the ignition switch and instrument panel components as indicated by the appropriate Service Manual. Page 1039 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 2549 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 1909 Convenience Center Page 2126 Wheel Hub: Service and Repair FRONT HUB/BEARING Fig. 3 Rotor Retaining Nuts. Removing Rotor From Spindle. K3500 Models REMOVE 1. Raise and support vehicle, then remove wheel and tire assembly. 2. Brake caliper. 3. Drive axle nut. 4. Remove rotor retaining bolts, Fig. 3, then using a wheel puller, remove hub/rotor assembly, Fig. 4. INSTALL 1. Reverse procedure to install. Page 1123 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3243 Throttle Position Sensor: Service and Repair Throttle Position (TP) Sensor NOTE: Since TP configurations can be mounted interchangeably, be sure to order the correct one for your engine with the identical part number of the one being replaced. REMOVE OR DISCONNECT 1. Electrical connector. 2. Two TP sensor attaching screw assemblies. 3. TP sensor from throttle body assembly. NOTE: The TP sensor is an electrical component and must not be soaked in any liquid cleaner or solvent, as damage may result. INSTALL OR CONNECT 1. With throttle valve in normally closed position, install TP sensor on throttle shaft and rotate counter clockwise to align mounting hole. 2. TP sensor attaching screw assemblies, precoated with appropriate thread.locking compound. Tighten Screw assemblies to 2.0 Nm (18.0 lb. in.). 3. Electrical connector. 4. Check for TP sensor output as follows: ^ Connect scan tool scanner to read TP sensor output voltage. ^ With ignition "ON" and engine stopped, TP sensor voltage should be less than 0.85 volt. If more than 0.85 volt, replace TP sensor. Page 3301 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 548 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Engine - Noise, Updated Exhaust Manifolds Exhaust Manifold: All Technical Service Bulletins Engine - Noise, Updated Exhaust Manifolds File In Section: 6 - Engine Bulletin No.: 37-66-02B Date: November, 1996 Subject: Engine Noise (Replace with New Design Cast Iron Exhaust Manifold and Stainless Steel Gasket) Models: 1982-95 Chevrolet and GMC C/K, R/V, G, P Models with 7.4L Engine (VIN N - RPO L19) and Cast Iron Exhaust Manifolds This bulletin is being revised to update the correction information statement and additional service parts information listed under all models. Please discard Corporate Bulletin Number 37-66-02A (Section 6 - Engine). Important: This bulletin does not apply to engines with stainless steel exhaust manifolds (Option H5D). Condition Some owners may comment on an engine noise. The noise is normally loudest when the engine is cold. Cause An exhaust leak may have developed between the cast iron exhaust manifold and the cylinder head mating surface. The cast iron exhaust manifold has warped at the ends. Correction A new exhaust manifold, stainless steel gasket and attaching hardware has been developed to correct this condition. Replace the existing cast iron exhaust manifold and gasket with the new design exhaust manifold, stainless steel gasket and new attaching hardware. Discard the existing hardware since it will not be reused. Page 2960 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 568 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 810 Coolant Temperature Sensor/Switch (For Computer): Locations Component View Engine Coolant Temperature (ECT) Sensor The Engine Coolant Temperature (ECT) Sensor is located on the intake manifold next to the thermostat housing. Engine - Cold Knock, Replace Oil Filter/Bearings/PROM Oil Filter: All Technical Service Bulletins Engine - Cold Knock, Replace Oil Filter/Bearings/PROM File In Section: 6 - Engine Bulletin No.: 37-61-05A Date: October, 1995 Subject: Cold Engine Knock (Replace Oil Filter/Bearings/PROM) Models: 1990-95 Chevrolet and GMC Truck C/K, R/V, S/T, M/L, G, P Models 1991-92 Oldsmobile Bravada with 4.3L (VIN Z - RPO LB4), 5.7L (VIN K - RPO L05), 7.4 (VIN N - RPO L19) Engine This bulletin is being revised to add the 1995 model year information. Please discard Corporate Bulletin Number 37-61-05 (Section 6 - Engine). Condition Some late model truck engines have been reported to exhibit "cold knock" on start up. "Cold Knock" usually occurs after the vehicle has been completely warmed up, then parked for 8 or more hours in ambient temperatures of 35° F or less. "Cold knock" can be separated into three distinct categories. 1. Short Duration - Harsh, deep metallic knock that usually lasts from 1 to 10 seconds. Generally classified as a bearing or rod knock. 2. Valve Train - Light clatter, tick or click that may last up to 1 minute. 3. Piston Slap - Metallic knock that occurs only under load. Piston slap may last as long as 5 minutes. Correction Category A: Short Duration Knock This matrix describes the repair for each affected model year and engine. Specific information for each affected model year and engine is supplied. Page 3224 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3681 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 460 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3752 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 2993 Fig.2-Symbols (Part 2 Of 3) Page 1004 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3084 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1601 What corrected the customer concern and was the repair verified? Please Explain: ............. Disclaimer Page 3140 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 2880 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 63 Important: Cruise control module ribbon must not be twisted when installed to cruise control module. 2. Install cruise control module per Section 9B of the Service Manual. 3. Connect cruise control cable end fitting to throttle body lever stud. If vehicle is equipped with accelerator control/cruise control cable adjuster (throttle relaxer), connect cruise control cable end fitting to adjuster. Note correct location of pulley for end fitting. 4. Adjust cruise cable per "Cable Assembly Adjustment" procedure in Section 9B of the Service Manual. Important: Excessive cable slack in cruise control cable will result in perceived slow module response. PARTS INFORMATION Parts are currently available from GMSPO. WARRANTY INFORMATION For vehicles repaired under warranty, use: Labor Operation Description Labor Time R1220 Module, C/C Replace Use Published Labor Operation time Page 2598 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. 4L60-E (M30) Transmission Electronic Component Location Views Page 3138 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3734 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table C1 Transmission Range Switch (C1) Page 3779 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 2844 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2810 PCM Connector Pin-Out Page 1000 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 1825 All 2006 and future model transmissions that use DEXRON(R)-VI are to be serviced ONLY with DEXRON(R)-VI fluid. DEXRON(R)-VI is an improvement over DEXRON(R)-III in the following areas: * These ATF change intervals remain the same as DEXRON(R)-III for the time being. 2006-2008 Transmission Fill and Cooler Flushing Some new applications of the 6L80 six speed transmission will require the use of the J 45096 Flushing and Flow Tester to accomplish transmission fluid fill. The clean oil reservoir of the machine should be purged of DEXRON(R)-III and filled with DEXRON(R)-VI. Parts Information Disclaimer Service and Repair Rocker Arm Assembly: Service and Repair Rocker arm studs that have damaged threads may be replaced with standard studs. Loose studs should be replaced with 0.003 inch or 0.013 inch oversize studs which are available for replacement. The rocker arm studs are threaded into the cylinder head. Unscrew studs to remove damaged/ worn studs. Coat threads on cylinder head end of stud with sealer before assembling to head. Page 2773 Catalytic Converter: Testing and Inspection Exhaust System Check RESTRICTED EXHAUST TEST Proper diagnosis for a restricted exhaust system is essential before any components are replaced. The following procedure(s) may be used for diagnosis: CHECK AT AIR PIPE - Remove the rubber hose at the exhaust manifold AIR pipe check valve and remove check valve. - Connect a fuel pump pressure gauge to a hose and nipple from a Propane Enrichment Device. - Insert the nipple into the exhaust manifold AIR pipe. CHECK AT 02 SENSOR - Carefully remove O2 sensor. - Install Exhaust Backpressure Tester in place of 02 sensor. - After completing the diagnosis described below, be sure to coat threads of 02 sensor with anti-seize compound prior to re-installation. DIAGNOSIS - With the engine idling at normal operating temperature, in park or neutral, observe the exhaust system backpressure reading on the gauge. The reading should not exceed 1.25 psi or 8.6 kPa. Increase engine speed to 2000 rpm and observe gauge. The reading should not exceed 3 psi or 20.7 kPa. - If the backpressure exceeds the given specifications, a restricted exhaust system is indicated. - Inspect the entire exhaust system for a collapsed pipe, heat distress, or possible internal muffler failure. - If there are no obvious reasons for the excessive backpressure, a restricted catalytic converter should be suspected, and replaced. WITH VACUUM GAUGE Engine at normal operating temperature: Connect a vacuum gauge to any convenient vacuum port on intake manifold. - Run engine at 1000 rpm and record vacuum reading. - Increase rpm slowly to 2500 rpm. Note vacuum reading at a steady 2500 rpm - If vacuum at 2500 rpm decreases more than 3" Hg, from reading at 1000 rpm, the exhaust system should be inspected for restrictions - Disconnect exhaust pipe from engine and repeat Step 2 & 3. If vacuum still drops more than 3" Hg, with exhaust disconnected, check for exhaust manifold restriction and valve timing. Recall - Tire Bead Damage During Mounting Technical Service Bulletin # 96-C-36 Date: 960601 Recall - Tire Bead Damage During Mounting 96-C-36 CAMPAIGN: TIRE BEAD DAMAGE....... Issued: 06/01/96 PRODUCT SAFETY CAMPAIGN SUBJECT: 96-C-36 - TIRE BEAD DAMAGE DURING MOUNTING (GENERAL TIRES ONLY) MODELS: 1995-1996 C/K CREW CAB AND G VAN 30 SERIES WITH RPO XHP/YHP-FLINT ASSEMBLY ONLY (VIN CODE "F") The Highway Safety Act, as amended, provides that each vehicle which is subject to a recall campaign of this type must be adequately repaired within a reasonable time after the customer has tendered it for repair. A failure to repair within sixty (60) days after tender of a vehicle is prima facie evidence of failure to repair within a reasonable time. If the condition is not adequately repaired within a reasonable time, the customer may be entitled to an identical or reasonably equivalent vehicle at no charge or to a refund of the purchase price less a reasonable allowance for depreciation. To avoid having to provide these burdensome remedies, every effort must be made to promptly schedule an appointment with each customer and to repair their vehicle as soon as possible. As you will see in reading the copy of the divisional letter that is being sent to customers, the customers are being instructed to contact the appropriate Customer Assistance Center if their dealer does not remedy the condition within five (5) days of the mutually agreed upon service date. If the condition is not remedied within a reasonable time, they are instructed on how to contact the National Highway Traffic Safety Administration. Defect/Vehicles Involved General Motors has decided that a defect which relates to motor vehicle safety exists in certain 1995-1996 G Vans 30 Series and C/K Crew Cab trucks equipped with General Ameri*550 AS LT225/75R16D tires. Some of these vehicles have bead damage to the tires which occurred during tire mounting. This damage to the tire reinforcing structure in the bead "toe" area would likely manifest itself as a bulge in the sidewall after the tire is inflated. The bulge may be noticeable when the tire is used in a single wheel position. But, if it is used in a dual rear wheel installation, the bulges on the tires would face each other and would not be noticeable. Typically, this condition would result in a slow air loss causing the tire to go flat. However, it is possible for the damage to result in a rapid air loss, which could cause injuries to anyone if they were handling the tire when this occurred. To correct this condition, dealers are to demount each General tire and inspect it for bead damage. If bead damage is present, the tire will be replaced. Involved are CERTAIN 1995-1996 G Vans 30 Series and C/K Crew Cab trucks equipped with General Ameri*550 AS LT225/75R16D tires, and built within the VIN breakpoints as shown. NOTICE: Dealers should confirm vehicle eligibility through VISS (Vehicle Information Service System) or Service Net (GMC only) prior to beginning campaign repairs. [Not all vehicles within the above breakpoints may be involved] Involved vehicles have been identified by Vehicle Identification Number. Computer listings containing the complete Vehicle Identification Number, customer name and address data have been prepared, and are being furnished to involved dealers with the campaign bulletin. The Customer name and Harness View Engine Engine - GM dexos 1 and dexos 2(R) Oil Specifications Engine Oil: Technical Service Bulletins Engine - GM dexos 1 and dexos 2(R) Oil Specifications INFORMATION Bulletin No.: 11-00-90-001 Date: March 14, 2011 Subject: Global Information for GM dexos1(TM) and GM dexos2(TM) Engine Oil Specifications for Spark Ignited and Diesel Engines, Available Licensed Brands, and Service Fill for Adding or Complete Oil Change Models: 2012 and Prior GM Passenger Cars and Trucks Excluding All Vehicles Equipped with Duramax(TM) Diesel Engines GM dexos 1(TM) Information Center Website Refer to the following General Motors website for dexos 1(TM) information about the different licensed brands that are currently available: http://www.gmdexos.com GM dexos 1(TM) Engine Oil Trademark and Icons The dexos(TM) specification and trademarks are exclusive to General Motors, LLC. Only those oils displaying the dexos‹›(TM) trademark and icon on the front label meet the demanding performance requirements and stringent quality standards set forth in the dexos‹›(TM) specification. Look on the front label for any of the logos shown above to identify an authorized, licensed dexos 1(TM) engine oil. GM dexos 1(TM) Engine Oil Specification Important General Motors dexos 1(TM) engine oil specification replaces the previous General Motors specifications GM6094M, GM4718M and GM-LL-A-025 for most GM gasoline engines. The oil specified for use in GM passenger cars and trucks, PRIOR to the 2011 model year remains acceptable for those previous vehicles. However, dexos 1(TM) is backward compatible and can be used in those older vehicles. In North America, starting with the 2011 model year, GM introduced dexos 1(TM) certified engine oil as a factory fill and service fill for gasoline engines. The reasons for the new engine oil specification are as follows: - To meet environmental goals such as increasing fuel efficiency and reducing engine emissions. - To promote long engine life. - To minimize the number of engine oil changes in order to help meet the goal of lessening the industry's overall dependence on crude oil. dexos 1(TM) is a GM-developed engine oil specification that has been designed to provide the following benefits: - Further improve fuel economy, to meet future corporate average fuel economy (CAFE) requirements and fuel economy retention by allowing the oil to maintain its fuel economy benefits throughout the life of the oil. - More robust formulations for added engine protection and aeration performance. Page 1792 - If replacing hose, remove retainer from hose and reinsert in connector. - If reusing hose and connector, retainer can remain in place on hose. Install or Connect 1. Push hose into connector until retainer tabs lock. Pull back on hose to check for proper engagement. 2. Inlet hose to heater core. 3. Inlet hose clamp. 4. Inlet hose mounting screw. Tighten screw to 1.4 Nm (12 lbs. in.). 5. Engine coolant. 6. Air cleaner. - Check the system for leaks. Page 245 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3677 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Tires/Wheels - Low Tire/Leaking Cast Aluminum Wheels Wheels: Customer Interest Tires/Wheels - Low Tire/Leaking Cast Aluminum Wheels TECHNICAL Bulletin No.: 05-03-10-003F Date: April 27, 2010 Subject: Low Tire Pressure, Leaking Cast Aluminum Wheels (Repair with Adhesive Sealant) Models: 2011 and Prior GM Passenger Cars and Light Duty Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X with Cast Aluminum Wheels Supercede: This bulletin is being revised to update the model years and the bulletin reference information. Please discard Corporate Bulletin Number 05-03-10-003E (Section 03 - Suspension). Condition Some customers may comment on a low tire pressure condition. Diagnosis of the low tire pressure condition indicates an air leak through the cast aluminum wheel. Cause Porosity in the cast aluminum wheel may be the cause. Notice This bulletin specifically addresses issues related to the wheel casting that may result in an air leak. For issues related to corrosion of the wheel in service, please refer to Corporate Bulletin Number 08-03-10-006C - Tire Slowly Goes Flat, Tire Air Loss, Low Tire Pressure Warning Light Illuminated, Aluminum Wheel Bead Seat Corrosion (Clean and Resurface Wheel Bead Seat). Correction 1. Remove the tire and wheel assembly from the vehicle. Refer to the appropriate service procedure in SI. 2. Locate the leaking area by inflating the tire to 276 kPa (40 psi) and dipping the tire/wheel assembly in a water bath, or use a spray bottle with soap and water to locate the specific leak location. Important - If the porosity leak is located in the bead area of the aluminum rim (where the tire meets the rim), the wheel should be replaced. - If two or more leaks are located on one wheel, the wheel should be replaced. 3. If air bubbles are observed, mark the location. - If the leak location is on the tire/rubber area, refer to Corporate Bulletin Number 04-03-10-001F Tire Puncture Repair Procedures for All Cars and Light Duty Trucks. - If the leak is located on the aluminum wheel area, continue with the next step. 4. Inscribe a mark on the tire at the valve stem in order to indicate the orientation of the tire to the wheel. 5. Dismount the tire from the wheel. Refer to Tire Mounting and Dismounting. 6. Remove the tire pressure sensor. Refer to Tire Pressure Sensor removal procedure in SI. 7. Scuff the INSIDE rim surface at the leak area with #80 grit paper and clean the area with general purpose cleaner, such as 3M(R) General Purpose Adhesive Cleaner, P/N 08984, or equivalent. 8. Apply a 3 mm (0.12 in) thick layer of Silicone - Adhesive/Sealant, P/N 12378478 (in Canada, use 88900041), or equivalent, to the leak area. 9. Allow for the adhesive/sealant to dry. Notice Caution must be used when mounting the tire so as not to damage the sealer. Damaging the repair area may result in an air leak. Page 2897 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3156 ^ Throttle angle is greater than 5%. Diagram Information and Instructions Data Link Connector: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1149 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 2503 coolant system integrity and will no longer be considered a 5 yr/150,000 mile (240,000 km) coolant. Coolant Removal Services/Recycling The tables include all coolant recycling processes currently approved by GM. Also included is a primary phone number and demographic information. Used DEX-COOL(R) can be combined with used conventional coolant (green) for recycling. Depending on the recycling service and/or equipment, it is then designated as a conventional 2 yr/30,000 mile (50,000 km) coolant or DEX-COOL(R) 5 yr/150,000 mile (240,000 km) coolant. Recycled coolants as designated in this bulletin may be used during the vehicle(s) warranty period. DEX-COOL(R) Recycling The DEX-COOL(R) recycling service listed in Table 2 has been approved for recycling waste engine coolants (DEX-COOL) or conventional) to DEX-COOL(R) with 5 yr/150,000 mile (240,000 km) usability. Recycling Fluid Technologies is the only licensed provider of Recycled DEX-COOL(R) meeting GM6277M specifications and utilizes GM approved inhibitor packages. This is currently a limited program being monitored by GM Service Operations which will be expanded as demand increases. Conventional (Green) Recycling Page 3177 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1437 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 134 Underhood Fuse/Relay Center Page 1096 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1711 Disclaimer Page 3679 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2122 5. Pull hub and drum straight off axle housing. Page 2631 Heater And A/C Control Select SW (C2), Stop Lamp & TCC Switch Jumper, Aux Fan Control SW Page 2082 hot particles embed themselves in the chrome layer and create a small pit. If the material is allowed to sit on the wheel while it is exposed to moisture or salt, it will corrode the wheel beneath the chrome leaving a pit or small blister in the chrome. Heavy brake dust build-up should be removed from wheels by using GM Chrome Cleaner and Polish, P/N 1050173 (in Canada use 10953013). For moderate cleaning, light brake dust build-up or water spots use GM Swirl Remover Polish, P/N 12377965 (in Canada, use Meguiars Plast-X(TM) Clear Plastic Cleaner and Polish #G12310C**). After cleaning, the wheel should be waxed using GM Cleaner Wax, P/N 12377966 (in Canada, use Meguiars Cleaner Wax #M0616C**), which will help protect the wheel from brake dust and reduce adhesion of any brake dust that gets on the wheel surface. For general maintenance cleaning, PEEK Metal Polish† may be used. It will clean and shine the chrome and leave behind a wax coating that may help protect the finish. Warranty of Stardust Corroded Chrome Wheels Wheels returned with pitting or spotting as a result of neglect and brake dust build-up may be replaced one time. Important Notify the customer that this is a one time replacement. Please stress to the customer the vital importance of keeping the wheels clean and free of prolonged exposure to brake dust build-up. "GM of Canada" dealers require prior approval by the District Manager - Customer Care and Service Process (DM-CCSP). Customer Assistance and Instructions GM has looked for ways customers may improve the appearance of wheels damaged by acidic cleaners. The following product and procedure has been found to dramatically improve the appearance of stained wheels. For wheels that have milky stains caused by acidic cleaners try the following: Notice THE 3M CHROME AND METAL POLISH REQUIRED FOR THIS PROCEDURE IS AN EXTREMELY AGGRESSIVE POLISH/CLEANER. THE WHEELS MUST BE CLEANED BEFORE APPLICATION TO AVOID SCRATCHING THE WHEEL SURFACE. THIS PRODUCT WILL REDUCE THE THICKNESS OF THE CHROME PLATING ON THE WHEEL AND IF USED INCORRECTLY OR EXCESSIVELY MAY REMOVE THE CHROME PLATING ALL TOGETHER, EXPOSING A LESS BRIGHT AND BRASSY COLORED SUB-LAYER. FOLLOW INSTRUCTIONS EXACTLY. 1. Wash the wheels with vigorously with soap and water. This step will clean and may reduce wheel staining. Flood all areas of the wheel with water to rinse. 2. Dry the wheels completely. Notice Begin with a small section of the wheel and with light pressure buff off polish and examine results. ONLY apply and rub with sufficient force and time to remove enough staining that you are satisfied with the results. Some wheels may be stained to the extent that you may only achieve a 50% improvement while others may be able to be restored to the original lustre. IN ALL CASES, only apply until the results are satisfactory. 3. Apply 3M Chrome and Metal Polish #39527* with a clean terry cloth towel. As you apply the polish, the staining will be diminished. 4. When dry, buff off the polish with a clean portion of the towel. 5. Repeat application of the 3M Chrome and Metal Polish until satisfied with the results. If continued applications fail to improve the appearance further discontinue use. This procedure will improve the appearance of the wheels and may, with repeated applications, restore the finish dramatically. For wheels that exhibit spotting from road chemicals the above procedure may marginally improve the condition but will not restore the finish or remove the pitting. In this type of staining the wheel finish has actually been removed in spots and no manner of cleaning will restore the finish. †*We believe this source and their products to be reliable. There may be additional manufacturers of such products/materials. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or material from this firm or for any such items that may be available from other sources. Parts Information Engine - Noise/Damage Oil Filter Application Importance Oil Filter: All Technical Service Bulletins Engine - Noise/Damage Oil Filter Application Importance INFORMATION Bulletin No.: 07-06-01-016B Date: July 27, 2009 Subject: Information on Internal Engine Noise or Damage After Oil Filter Replacement Models: 2010 and Prior Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X Supercede: This bulletin is being updated to add model years. Please discard Corporate Bulletin Number 07-06-01-016A (Section 06 - Engine/Propulsion System). Important Engine damage that is the result of an incorrect or improperly installed engine oil filter is not a warrantable claim. The best way to avoid oil filter quality concerns is to purchase ACDelco(R) oil filters directly from GMSPO. Oil filter misapplication may cause abnormal engine noise or internal damage. Always utilize the most recent parts information to ensure the correct part number filter is installed when replacing oil filters. Do not rely on physical dimensions alone. Counterfeit copies of name brand parts have been discovered in some aftermarket parts systems. Always ensure the parts you install are from a trusted source. Improper oil filter installation may result in catastrophic engine damage. Refer to the appropriate Service Information (SI) installation instructions when replacing any oil filter and pay particular attention to procedures for proper cartridge filter element alignment. If the diagnostics in SI (Engine Mechanical) lead to the oil filter as the cause of the internal engine noise or damage, dealers should submit a field product report. Refer to Corporate Bulletin Number 02-00-89-002I (Information for Dealers on How to Submit a Field Product Report). Disclaimer Page 3592 Spark Plug: Description and Operation DESCRIPTION Resistor-type, tapered-seat spark plugs are used on this engine. No gasket is used on these spark plugs. Application and ID explains the letter coding on these spark plugs. A dot before the spark plug code or the letter "C" after the number in the code indicates the spark plug has a copper core. Refer to Specification / Mechanical or to the vehicle emissions control information label for correct gap information. CONSTRUCTION These spark plugs have a ceramic insulator that is approximately 6.35 mm (1/8 inch) longer than conventional spark plugs. The longer length spark plugs magnify the problem of cracked insulators because most spark plug sockets are not of sufficient length to properly engage the shell hex. If the spark plug shell hex is not fully engaged in the spark plug socket wrench, the socket may cause insulator cracking and/or breakage during plug installation or removal. OPERATION When servicing these spark plugs, make sure the spark plug socket being used is deep enough to accommodate the longer length insulator. Use of a spark plug socket that is NOT deep enough may result in the ceramic insulator becoming cracked above the spark plug shell. Normal or average service is assumed to be a mixture of idling, low speed, and high speed operation with some of each making up the total daily driving. Occasional or intermittent high-speed driving is essential to good spark plug performance. It provides increased and sustained combustion heat that burns away excess deposits of carbon or oxide that may have accumulated from frequent idling or continual stop-and-go or slow-speed driving. Spark plugs are protected by an insulating boot made of special heat-resistant material that covers the spark plug terminal and extends downward over a portion of the plug insulation These boots prevent flash-over with resultant missing of the engine. Do not mistake corona discharge for flash-over or a shorted insulator. Corona discharge is a steady blue light appearing around the insulator, just above the shell crimp. It is the visible evidence of a high-tension field and has no effect on ignition performance. Usually it can be detected only in darkness. This discharge may repel dust particles, leaving a clear ring on the insulator just above the shell. This ring is sometimes mistakenly regarded as evidence that combustion gases have blown out between the shell and insulator. Diagram Information and Instructions Camshaft Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3189 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 2650 Heater Case (1 OF 2) Heater Case (2 OF 2) Install or Connect 1. Heater core into retainer. - Install seven screws that hold heater cover to heater case. 2. Heater cover. - Make sure heater cover is properly sealed. 3. Heater case. - May be necessary to have an assistant when installing heater case. 4. Nuts. 5. Screws. 6. Screws Tighten Screws on engine side of the cowl to 1.9 Nm (17 lb in). - Nuts to 2.8 Nm (25 lb in). - Screw on interior side of the cowl to 11 Nm (97 lb in). 7. Heater hoses. 8. Coolant recovery reservoir. 9. Roll instrument panel forward. 10. Steering column. 11. Blower motor. 12. Blower motor cover. 13. Hinge pillar trim panels. 14. Center floor air distribution duct. 15. Electrical connectors, as necessary. 16. Instrument panel storage compartment. 17. Engine coolant. - Check the system for leaks. Page 394 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 2483 Spark Plug: Description and Operation DESCRIPTION Resistor-type, tapered-seat spark plugs are used on this engine. No gasket is used on these spark plugs. Application and ID explains the letter coding on these spark plugs. A dot before the spark plug code or the letter "C" after the number in the code indicates the spark plug has a copper core. Refer to Specification / Mechanical or to the vehicle emissions control information label for correct gap information. CONSTRUCTION These spark plugs have a ceramic insulator that is approximately 6.35 mm (1/8 inch) longer than conventional spark plugs. The longer length spark plugs magnify the problem of cracked insulators because most spark plug sockets are not of sufficient length to properly engage the shell hex. If the spark plug shell hex is not fully engaged in the spark plug socket wrench, the socket may cause insulator cracking and/or breakage during plug installation or removal. OPERATION When servicing these spark plugs, make sure the spark plug socket being used is deep enough to accommodate the longer length insulator. Use of a spark plug socket that is NOT deep enough may result in the ceramic insulator becoming cracked above the spark plug shell. Normal or average service is assumed to be a mixture of idling, low speed, and high speed operation with some of each making up the total daily driving. Occasional or intermittent high-speed driving is essential to good spark plug performance. It provides increased and sustained combustion heat that burns away excess deposits of carbon or oxide that may have accumulated from frequent idling or continual stop-and-go or slow-speed driving. Spark plugs are protected by an insulating boot made of special heat-resistant material that covers the spark plug terminal and extends downward over a portion of the plug insulation These boots prevent flash-over with resultant missing of the engine. Do not mistake corona discharge for flash-over or a shorted insulator. Corona discharge is a steady blue light appearing around the insulator, just above the shell crimp. It is the visible evidence of a high-tension field and has no effect on ignition performance. Usually it can be detected only in darkness. This discharge may repel dust particles, leaving a clear ring on the insulator just above the shell. This ring is sometimes mistakenly regarded as evidence that combustion gases have blown out between the shell and insulator. Page 3366 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3050 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3829 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3493 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 526 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 3507 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3513 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 492 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 2709 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1558 ^ For 1993 and prior vehicles, splice into CKT 50 (BRN) between connector C152 and GT101 (Figures 2, 3, 4). Page 1116 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 982 Oxygen Sensor: Mechanical Specifications Oxygen Sensor .................................................................................................................................... ........................................................ 41 Nm (30 lb.ft.) Page 3955 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 934 Fig.1-Symbols (Part 1 Of 3) Page 1252 Fig.1-Symbols (Part 1 Of 3) Page 208 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 1003 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Diagram Information and Instructions Engine Control Module: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3847 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3150 K Series - 4 Wheel Drive Page 3656 Fig.1-Symbols (Part 1 Of 3) Page 3013 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3584 Distributor: Description and Operation Distributor OPERATION The distributor is driven by the camshaft and mounts to the rear of the engine, it does not contain centrifugal advance weights, springs, or a vacuum advance unit. The distributor has an internal magnetic pickup assembly that contains a permanent magnet, a pole piece with internal teeth, and a pickup coil. When the rotating teeth of the timer core line up with the teeth of the pole piece, voltage is induced in the pickup coil. This voltage signals the Ignition Control Module (ICM) to trigger the primary ignition circuit. Current flow in the primary circuit is interrupted and up to 35,000 volts is induced in the ignition coil secondary winding. This high voltage is directed through the secondary ignition circuit to fire the spark plugs. No periodic lubrication is required. Engine oil lubricates the lower bushing. The upper bushing is prelubricated and sealed. Page 3639 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 1167 Oil Pressure Switch (For Fuel Pump): Description and Operation PURPOSE: As a back-up system to the fuel pump relay, the fuel pump is also turned ON by the oil pressure switch. OPERATION: When the engine oil pressure reaches about 28 kPa (4 psi), through cranking the oil pressure switch will close to complete the circuit to the fuel pump. Front Wheel Bearing: Service and Repair Front FRONT WHEEL BEARINGS AND/OR HUB Fig. 3 Rotor Retaining Nuts. Removing Rotor From Spindle. K3500 Models NOTICE: The front wheel bearings are not serviceable. The hub and bearing must be replaced as a complete unit. REMOVE 1. Raise and support vehicle, then remove wheel and tire assembly. 2. Brake caliper. 3. Drive axle nut. 4. Remove rotor retaining bolts, Fig. 3, then using a wheel puller, remove hub/rotor assembly, Fig. 4. INSTALL 1. Reverse procedure to install. Torque drive axle nut to 173 ft lbs Electric Clutch Release Switch Clutch Switch: Description and Operation Electric Clutch Release Switch Fig. 3 Electric clutch release switch On models equipped with manual transmission, a plunger type clutch switch, Fig. 3, is used in series with the two brake switches. The switch disengages the cruise control system when the clutch pedal is depressed. When the clutch pedal is released, the system will remain disengaged. Diagrams C212, C237, C302: Powerseat To Cross Body Harn, Rear Body Harn To Cross Body Harn, Body Harn To Cross Body Harn, Cargo Lamp Switch, Endgate Release Switch Page 3181 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3112 Fig.1-Symbols (Part 1 Of 3) Page 1461 Heater And A/C Control Select SW (C2), Stop Lamp & TCC Switch Jumper, Aux Fan Control SW Page 2289 condition, install the appropriate main bearings as determined by the following procedure. Calibration Information - 1992-93 LB4 VIN Z The revised PROMs reduce spark advance after the engine is started. The reduction in spark lowers the cylinder pressure and eliminates the knock. The revised PROMs will NOT eliminate a piston slap (Category C) or valve train noise (Category B) concern. The base cold knock PROM contains the previously released calibration updates. For 1992 LB4, the previous field release is included for torque converter clutch (TCC) lock up (see Bulletin 137107 - Chevrolet 92-75-7A; GMC Truck 92-7A-40; Oldsmobile 92-T-34; Canada 9274L60100) for automatic transmissions, or neutral gear rattle for manual transmissions (see Bulletin 267201R - Chevrolet 92-187B-7B; GMC Truck 92-7B-149A; Canada 93-7B-105). If a vehicle has had a detonation fix PROM installed previously, select the combined detonation and cold knock fix PROM for the application. See Bulletin 376508 for more information on field fix PROM for the application and detonation. Important: Use of a detonation fix PROM in a non-detonating vehicle may result in degraded driveability. GMSPO currently stocks three (3) PROMs for each light duty 1992 model year LB4 application. Base Cold Knock Fix Combination Cold Knock and Detonation Fix GMSPO Service Parts Assistance Center (SPAC 1-800-433-6961) will have information available on each PROM part number. Select the PROM from the table. Old Broadcast Code (Old B/C Code) and Scan I.D. information has been supplied to help installed previously. Use a TECH-1 to determine the Scan I.D. of the PROM in the vehicle or remove the PROM and read the Broadcast Code (B/C Code). If the B/C Code/Scan I.D. can be found in the first table, a detonation fix has not been installed. PROMs are currently available GMSPO. 1990-95 L05 VIN K Page 3438 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 529 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 2870 Fig.1-Symbols (Part 1 Of 3) Page 1091 Vehicle Speed Sensor: Connector Locations Electronic 4-Speed Automatic Overdrive Transmission W/4WD Specifications Temperature Vs Resistance Value Page 2627 Coolant Temperature Sensor/Switch (For Computer): Service and Repair Engine Coolant Temperature (ECT) Sensor NOTE: Care must be taken when handling engine coolant temperature sensor. Damage to the Engine Coolant Temperature (ECT) sensor will affect proper operation of the fuel injection system. REMOVAL 1. Disconnect negative battery cable. 2. Drain cooling system below level of sensor. 3. Disconnect electrical connector. 4. Remove ECT sensor. INSTALLATION 1. Install sensor in engine. 2. Connect electrical connector. 3. Refill cooling system. 4. Connect negative battery cable. Page 1545 System Component Locations Air Bag Control Module: Locations System Component Locations Fig. 4 Air Bag System Component Locations Refer to Fig. 4 for air bag system component locations. Page 2551 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3248 Electronic 4-Speed Automatic Overdrive Transmission Page 829 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 2218 Valve Clearance: Specifications Valve Arrangement FRONT TO REAR 7.4L/V8-454 ......................................................................................................................................... ........................................................... E-I-E-I-E-I-E-I Page 3937 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Specifications Engine Oil Pressure: Specifications Normal Oil Pressure, psi .............................................................................................................. 10 psi @ 500 RPM minimum; 40-60 psi @ 2000 RPM. Page 1336 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1984 address data furnished will enable dealers to follow up with customers involved in this campaign. Any dealer not receiving a computer listing with the campaign bulletin has no involved vehicles currently assigned. These dealer listings may contain customer names and addresses obtained from State Motor Vehicle Registration Records. The use of such motor vehicle registration data for any other purpose is a violation of law in several states. Accordingly, you are urged to limit the use of this listing to the follow up necessary to complete this campaign. Parts/Customer Information Locations Underhood Fuse/Relay Center Page 2624 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 744 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3170 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 173 PCM Connector Pin-Out Page 2889 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2112 Painting Process System: Dupont Products Paint Color Information: Corsican Silver WA EQ9283 Dupont # C9143, Sparkle Silver WA9967 Dupont # C9339 1. Wipe wheel with cleaning solvent: 3939-S, 3949-S or 3900-S. 2. Mask off tires. Important: 3. Mask off all wheel mounting surfaces and wheel mount surfaces. 4. Apply two coats of 615/616-S etching primer to wheel allowing 10 minutes flash between coats. Allow to dry for 30 minutes before applying primer coat. 5. Apply URO 5000 primer 1220/193-S + accelerator 389-S using two coats at 65-70 PSI at the gun. Allow 12-15 minutes between coats. Force bake 30 minutes at 140°F (60°C). 6. Scuff sand using green Scotch-Brite pad. 7. Solvent wipe before top coating. 8. Apply IMRON 6000 base coat to wheel. 2-3 coats to hiding at 60-70 PSI allowing to flash between coats. Base coat needs to dry 20-30 minutes before clearcoat is applied. 9. Apply 3440-S clearcoat to wheel using two coats at 60-70 PSI. Flash 10-15 minutes between coats. 389-S can be used in basecoat and clearcoat to give faster set up times. 10. Allow overnight dry before reassemble. Can be baked for 30 minutes at 140°F (60°C). Attachment 2 - PPG Products Painting Process: PPG System Paint Color Information: Corsican Silver WAEQ9283; PPG # DBC-3531, Sparkle Silver WA9967; PPG # 35367 1. Wash entire wheel with aluminum cleaner DX533, mix 1:3 with water. Allow to react 2-3 minutes and rinse thoroughly. 2. Wash entire wheel with aluminum conditioner DX5O3 straight from the container. Allow to react 2-3 minutes until pale gold or tan color develops. Rinse thoroughly and dry. 3. Mask off tires. Important: 4. Mask off all wheel nut mounting surfaces and wheel mounting surfaces. 5. Apply 1-2 coats of DP Primer and allow to flash for 15-20 minutes. 6. Apply 2-3 coats of Deltron Basecoat (DBC) and allow to flash 20 minutes after the final coat. 7. Apply two (2) wet coats of Concept 2001 Acrylic urethane. 8. Flash 20 minutes and bake 140°F (60°C) for 30 minutes. For more information contact your PPG Jobber. Attachment 3 - Spies Hecker Painting Process: Spies Hecker System Paint Color Information: Corsican Silver AWEQ9283; SH-72913, Sparkle Silver WA9967; SH-71912 1. Clean with Permahyd Silicone Remover 7090. 2. Mask off tires. Page 3655 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1632 Disclaimer Diagram Information and Instructions Oxygen Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Locations Control Module HVAC: Locations BLOWER CONTROL MODULE HVAC Control Panel & Module The Blower Control Module is attached to Control Assembly. The Control Assembly is located in center of Instrument Panel (I/P). Page 3357 Fig.2-Symbols (Part 2 Of 3) Page 3621 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1472 Fig.1-Symbols (Part 1 Of 3) Page 1189 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3094 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 3860 Engine Page 1672 Distributor: Description and Operation Distributor OPERATION The distributor is driven by the camshaft and mounts to the rear of the engine, it does not contain centrifugal advance weights, springs, or a vacuum advance unit. The distributor has an internal magnetic pickup assembly that contains a permanent magnet, a pole piece with internal teeth, and a pickup coil. When the rotating teeth of the timer core line up with the teeth of the pole piece, voltage is induced in the pickup coil. This voltage signals the Ignition Control Module (ICM) to trigger the primary ignition circuit. Current flow in the primary circuit is interrupted and up to 35,000 volts is induced in the ignition coil secondary winding. This high voltage is directed through the secondary ignition circuit to fire the spark plugs. No periodic lubrication is required. Engine oil lubricates the lower bushing. The upper bushing is prelubricated and sealed. Page 1663 Page 106 Cruise Control Module: Service and Repair Fig. 15 Cruise control module & cable replacement 1. Disconnect battery ground cable. 2. Disconnect cruise control cable from module, Fig. 15. 3. Remove module attaching screws, then disconnect electrical connector and remove module. The module cannot be serviced. 4. Reverse procedure to install. Page 2720 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3209 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 561 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1771 13. Using template (Figure 5), mark cutting lines on the lower evaporator case using a china marker or equivalent (Figure 1). 14. Cut through the plastic upper evaporator case and the lower evaporator case following the marked outlines of the templates to create two access doors (Figure 1). Do not cut rear edge of either access door (Figure 4 and 5). Use a hot knife or a small (1/2" dia.) rotary abrasive cutting wheel. Page 3814 PCM Connector Pin-Out Page 2717 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 2617 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 249 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1988 customer for periodic servicing. When installing the Campaign Identification Label, be sure to install the clear protective covering. Additional Campaign Identification Labels can be obtained from VISPAC Incorporated by calling 1-800-269-5100 (Monday-Friday, 8:00 a.m. to 4:30 p.m. EST). Ask for Item Number S-1015 when ordering. Apply the "Campaign Identification Label" only on a clean, dry surface. Submit a Product Campaign Claim with the information as shown. Refer to the General Motors Corporation Claims Processing Manual for details on Product Campaign Claim Submission. Owner Letter June, 1996 Dear Chevrolet Truck Customer: This notice is sent to you in accordance with the requirements of the National Traffic and Motor Vehicle Safety Act. REASON FOR THIS RECALL General Motors has decided that a defect which relates to motor vehicle safety exists in certain 1995-1996 G Vans 30 Series and C/K Crew Cab trucks equipped with General Ameri*550 AS LT225/75R16D tires. Some of these vehicles have bead damage to the tires which occurred during tire mounting. This damage to the tire reinforcing structure in the bead "toe" area would likely manifest itself as a bulge in the sidewall after the tire is inflated. The bulge may be noticeable when the tire is used in a single wheel position. But, if it is used in a dual rear wheel installation, the bulges on the tires would face each other and would not be noticeable. Typically, this condition would result in a slow air loss causing the tire to go flat. However, it is possible for the damage to result in a rapid air loss, which could cause injuries to anyone if they were handling the tire when this occurred. WHAT WE WILL DO To correct this condition, your Chevrolet dealer will demount each General tire and inspect it for bead damage. If bead damage is present, the tire will be replaced. This service will be performed for you at no charge. WHAT YOU SHOULD DO Please contact your Chevrolet dealer as soon as possible to arrange a service date and so the dealer may order the necessary parts for the repair. Instructions for making this correction have been sent to your dealer. The labor time necessary to perform this service correction is approximately 1 hour and 15 minutes to 3 hours and 45 minutes depending on the number of tires involved. Please ask your dealer if you wish to know how much additional time will be needed to schedule and process your vehicle. The enclosed owner reply card identifies your vehicle. Presentation of this card to your dealer will assist in making the necessary correction in the shortest possible time. If you have sold or traded your vehicle, please let us know by completing the postage paid reply card and returning it to us. Your Chevrolet dealer is best equipped to provide service to ensure that your vehicle is corrected as promptly as possible. If, however, you take your vehicle to your dealer on the agreed service date, and they do not remedy this condition on that date or within five (5) days, we recommend you contact the Chevrolet Customer Assistance Center by calling 1-800-222-1020. Page 3429 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3049 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3290 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 207 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1770 12. Using template (Figure 4), mark cutting lines on the upper evaporator case using a china marker or equivalent. Do not remove the locating tabs from the templates, they are needed to position the cut area for the access doors (Figure 1). Page 3114 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3693 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2893 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1071 Transmission Position Switch/Sensor: Locations Park/Neutral Position and Backup Lamp Switch, With 4WD HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 550 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Capacity Specifications Engine Oil: Capacity Specifications TYPE.................................................................................................................................................... .......................................................................SG, SH CAPACITY, Refill: 6-cyl. 4.3L............................................................................................................... ........................................................................3.8 Liters* 4.0 Quarts* 8-cyl. 5.7L 1992-94.................. ...........................................................................................................................................................4. 7 Liters 5.0 Quarts Others................................................................................................................................................... .....................................3.8 Liters 4.0 Quarts 8-cyl. 7.4L: 1988-90.............................................................................................................................. ..............................................4.8 Liters 5.0 Quarts 1991-94................................................................................................................................................ .................................6.6 Liters* 7.0 Quarts* Others............................................................................. ...........................................................................................................5.7 Liters 6.0 Quarts Capacity shown is without filter. When replacing filter, additional oil may be added. *1992-93 C3500 models add an additional one (1) quart (0.95L) Above 40°F (4°C)...................................................... .........................................................................................................................................................30 ‡ Above 0°F (-18°C)................................................................................................................................ ...................................................................10W-30** Below 60°F (16°C)............................................ ............................................................................................................................................................5 W-30 **Preferred ‡May be used when other recommended viscosities are unavailable Page 3034 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2601 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 498 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 691 Brake Light Switch: Electrical Diagrams Antilock Brakes (Part 1 Of 2) Four Wheel Antilock Brakes (4WAL) Page 1699 Page 766 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3676 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3270 HD 5-Speed Manual Transmission W/4WD Page 399 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Diagram Information and Instructions Crankshaft Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1581 Front Door Wiring Page 1678 Spark Plug: Service Precautions WARNING: If you smoke while handling coated spark plugs, wear gloves to prevent transfer of coating to cigarette and subsequent burning of coating. Always wash hands after handling coated plugs. CAUTION: Observe service precautions: - Allow engine to cool BEFORE removing spark plugs. Attempting to remove spark plugs from a hot engine may cause plug to seize, causing damage to cylinder head threads. - Clean spark plug recess area BEFORE removing plug. Failure to do so can result in engine damage due to dirt or foreign material entering cylinder head, or in contamination of cylinder head threads. Contaminated threads may prevent proper seating of new plug. - Use only spark plugs specified for use in the vehicle. DO NOT install spark plugs that are either "hotter" or "colder" than those specified for the vehicle. Installing plugs of another type can severely damage the engine. Page 3961 Knock Sensor Circuit CIRCUIT DESCRIPTION The Knock Sensor (KS) system consist of a knock sensor with one wire that goes directly to the PCM. There is a check performed by the PCM. The check consist of monitoring CKT 496 for a voltage that is more than 0.04 volt and less than 4.6 volts. If the voltage is either too high or too low for 16 or more seconds, DTC 43 will set. CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic chart. 1. The first test is to determine if the system is functioning at the present time. 2. Test two determines the state of the 5 volt reference voltage applied to the knock sensor circuit. DIAGNOSTIC AIDS The PCM applies 5 volts to CKT 496. A 3900 ohm resistor in the knock sensor reduces the voltage to about 2.5 volts. When knock occurs, the knock sensor produces a small AC voltage that rides on top of the 2.5 volts already applied. An AC voltage monitor, in the PCM, is able to read this signal as knock and incrementally retard spark. If the KS system checks OK, but detonation is the complaint, refer to Diagnosis By Symptom / Detonation, Spark Knock See: Testing and Inspection/Symptom Related Diagnostic Procedures/Detonation/ Spark Knock Page 2876 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3271 5-Speed Manual Transmission W/4WD Page 3941 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3241 Throttle Position Sensor: Testing and Inspection This check should be performed when TP sensor attaching parts have been replaced. A Tech 1 scan tool can be used to read the TP sensor output voltage, or: 1. Connect digital voltmeter J 39200 or equivalent, from TP sensor connector terminal "B" (BLK wire) to terminal "C" (DK BLU wire). 2. With ignition "ON," engine stopped, the TP sensor voltage should be less than 0.85 volt if more than 0.85 volt verify free throttle movement. If still more than 0.85 volt, replace TP sensor. 3. Remove the voltmeter and jumpers, reconnect the TP sensor connector to the sensor. Page 1917 Underhood Fuse/Relay Center Page 3694 Fig.1-Symbols (Part 1 Of 3) Page 3699 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 1453 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 210 Pinout Description: C1 (Part 2 Of 2) Engine Controls - TBI, C2 Controlled Idle Speed Idle Speed: Adjustments Controlled Idle Speed Before performing this check, there should be no DTC(s) displayed, idle air control system has been checked and ignition timing correct. 1. Set parking brake and block drive wheels. 2. Connect a Tech 1 scan tool to the DLC connector with tool in open mode. 3. Start engine and bring it to normal operating temperature. 4. Check for correct state of PRNDL position (R-D-L) switch on Tech 1 scan tool. 5. Check specifications for controlled idle speed and IAC valve pintle position (counts). 6. If within specifications, the idle speed is being correctly controlled by the control module. 7. If not within specifications, refer to Rough, Unstable or Incorrect Idle, Stalling. See: Fuel Delivery and Air Induction/Testing and Inspection Page 973 C Series - 2 Wheel Drive 1994-1995 C/K TRUCK 3A-72 Front Axle Drive Shaft Seal - Wears Out Early Constant Velocity Joint Boot: All Technical Service Bulletins Front Axle Drive Shaft Seal - Wears Out Early File In Section: 3 - Steering/Suspension Bulletin No.: 56-33-01A Date: December, 1995 Subject: Early Front Axle Front Wheel Drive Shaft Seal Wear-out (Replace Lower Control Arm or Install Seal Cover) Models: 1988-95 Chevrolet and GMC Truck K Models - Plant Codes Z, 1, E Built Prior to VIN Breakpoints: 1995 Chevrolet and GMC Truck K Models - Plant Code J Built Prior to VIN Breakpoints: This bulletin is being revised to correct the "Models" involved information. Please discard Corporate Bulletin Number 56-33-01 (Section 3 - Steering/Suspension). Condition Some owners of vehicles which operate primarily in off-highway environments may comment on premature wear-out of the front axle seals (front wheel drive shaft CV boots). Cause Off-highway usage can result in the build-up of debris (mud, ice, etc.) on the lower control arm. If the amount of debris is excessive, contact with the front axle front wheel drive shaft seal may result. The result may be an early wear-out of the seal. Correction Important: Implementation of this bulletin by Canadian dealers on vehicles within warranty period requires prior DSM approval. K - Models with 8600 # GVW's and Below Page 2727 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1279 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1108 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 2504 Processes shown in the Table 3 are capable of recycling waste engine coolants (DEX-COOL(R) or conventional) to a conventional (green) coolant. Recycling conventional coolant can be accomplished at your facility by a technician using approved EQUIPMENT (listed by model number in Table 3), or by an approved coolant recycling SERVICE which may recycle the coolant at your facility or at an offsite operation. Refer to the table for GM approved coolant recyclers in either of these two categories. Should you decide to recycle the coolant yourself, strict adherence to the operating procedures is imperative. Use ONLY the inhibitor chemicals supplied by the respective (GM approved) recycling equipment manufacturer. Sealing Tablets Cooling System Sealing Tablets (Seal Tabs) should not be used as a regular maintenance item after servicing an engine cooling system. Discoloration of coolant can occur if too many seal tabs have been inserted into the cooling system. This can occur if seal tabs are repeatedly used over the service life of a vehicle. Where appropriate, seal tabs may be used if diagnostics fail to repair a small leak in the cooling system. When a condition appears in which seal tabs may be recommended, a specific bulletin will be released describing their proper usage. Water Quality The integrity of the coolant is dependent upon the quality of DEX-COOL(R) and water. DEX-COOL(R) is a product that has enhanced protection capability as well as an extended service interval. These enhanced properties may be jeopardized by combining DEX-COOL(R) with poor quality water. If you suspect the water in your area of being poor quality, it is recommended you use distilled or de-ionized water with DEX-COOL(R). "Pink" DEX-COOL(R) DEX-COOL(R) is orange in color to distinguish it from other coolants. Due to inconsistencies in the mixing of the dyes used with DEX-COOL(R), some batches may appear pink after time. The color shift from orange to pink does not affect the integrity of the coolant, and still maintains the 5 yr/150,000 mile (240,000 km) service interval. Back Service Only use DEX-COOL(R) if the vehicle was originally equipped with DEX-COOL(R). Page 1447 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3422 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1542 Page 2848 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3194 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 939 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 534 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 212 Engine Control Module: Description and Operation Powertrain Control Module (PCM) PURPOSE The Powertrain Control Module (PCM) is the control center of the fuel injection system. It constantly looks at the information from various sensors (inputs) and controls the systems (outputs) that affect vehicle performance. The control module also performs the diagnostics of the system. It can recognize operational problems, alert the driver through the Malfunction Indicator Lamp (MIL) "Service Engine Soon" light on the instrument panel and store a Diagnostic Trouble Code(s) (DTC) in the control module memory. The DTC identifies the problem areas to aid the technician in performing repairs. OPERATION The PCM is an electronic computer designed to process the various input information, and send the necessary electrical response to control fuel delivery, spark control, and other emission control systems. The control module can control these devices through the use of Quad Driver Modules (QDM). When the control module is commanding a device or a component "ON," the voltage potential of the output is "LOW" or near zero volts. When the control module is commanding a device or component "OFF," the voltage potential of the circuit will be "HIGH," or near 12 volts. The primary function of the QDM is to supply the ground for the component being controlled. The input information has an interrelation between sensor output. If one of the input devices failed, such as the oxygen sensor, this could affect more than one of the systems controlled by the computer. The PCM has two parts for service: - Controller which is the control module without the PROM (MEM-CAL). - PROM (Programmable Read Only Memory) which is a separate memory calibrator unit LEARNING ABILITY The PCM has a "learning" ability which allows it to make corrections for minor variations in the fuel system to improve driveability. If the battery is disconnected, to clear diagnostic trouble codes or for other repairs. The "learning" process resets and begins again. A change may be noted in the vehicle's performance. To "teach" the vehicle, ensure the engine is at operating temperature. The vehicle should be driven at part throttle, with moderate acceleration and idle conditions until normal performance returns. NOTE: The PCM must be maintained at a temperature below 85°C (185°F) at all times. This is most essential if the vehicle is put through a baking process. The control module will become inoperative if it's temperature exceeds 85°C (185°F). It is recommended that temporary insulation be placed around the control module during the time the vehicle is in a paint oven or other high temperature processes. Locations Powertrain Control Module (PCM) Page 1659 Timing Mark Page 3314 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 84 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 258 Fuel Pump Relay: Description and Operation OPERATION When the key is first turned "ON" without the engine running, the control module turns a fuel pump relay "ON" for two seconds. This builds up the fuel pressure quickly. If the engine is not started within two seconds, the control module shuts the fuel pump "OFF," and waits for ignition reference pulses. As soon as the engine is cranked, the control module turns the relay "ON" and runs the fuel pump. When the engine is cranking or operating, the control module receives distributor ignition reference pulses which also energize the injectors. As a backup system to the fuel pump relay, the fuel pump is also turned "ON" by an oil pressure switch. When the engine oil pressure reaches about 28 kPa (4 psi), through cranking the oil pressure switch will close to complete the circuit to the fuel pump. An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold. The oil pressure switch will turn "ON" the fuel pump as soon as oil pressure reaches about 28 kPa (4 psi). Page 1218 Fig.1-Symbols (Part 1 Of 3) Page 3517 Knock Sensor Circuit Page 2596 Fig.1-Symbols (Part 1 Of 3) Page 3815 Engine Control Module: Locations Powertrain Control Module (PCM) Page 3015 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 824 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3956 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 2351 Oil Pressure Switch Page 1834 Fluid - A/T: Service and Repair The normal schedule is 30,000 miles for vehicles under 8600 lbs. GVWR OR 24,000 for vehicles over 8600 lbs. GVWR. If vehicle is driven in heavy city traffic where outside temperature regularly reaches 90°F or higher, in hilly or mountain terrain, is used for frequent trailer pulling or is used in taxi, police, delivery or other commercial service, maintenance schedule for drain and refill is 15,000 miles for all vehicles under 8600 lbs. GVWR or 12,000 miles for vehicles over 8600 lbs. GVWR. Change fluid and filter as follows: 1. Raise vehicle and position drain pan under transmission pan. 2. Remove front and side attaching bolts from the oil pan. 3. Loosen rear attaching bolts approximately four turns. 4. Carefully pry transmission pan loose and allow fluid to drain. 5. Remove rear attaching bolts, pan and pan gasket. 6. Drain remaining fluid from pan, then clean pan and gasket surfaces with solvent and dry with compressed air. 7. Remove transmission screen. Remove seal from intake pipe or case bore. 8. Replace screen if applicable, or thoroughly clean screen assembly with solvent and dry with compressed air. 9. Install seal on intake pipe, then install screen assembly. 10. Install gasket on pan, then install pan and tighten to specifications. 11. Lower vehicle and add approximately 9 pts. of Dexron II type transmission fluid through filler tube. 12. Start engine and let run at idle, then with brakes applied move selector lever through each gear range. 13. Place transmission in Park position and check fluid level. Component Locations Oxygen Sensor (O2S) Page 994 Oxygen Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 2714 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3286 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 2467 Spark Plug Wire: Testing and Inspection VISUAL INSPECTION 1. Inspect the routing of the wires. Improper routing can cause crossfiring. 2. Inspect each wire for any signs of cracks or splits in the wire. 3. Inspect each boot for signs of tears, piercing, arc through, or carbon tracking. If the boot needs to be replaced, twist it a half-turn in either direction to break the seal before pulling on the boot to remove the wire. SPARK PLUG WIRE RESISTANCE TEST 1. Disconnect both ends of each wire. Make sure the wire terminals are clean. 2. Set J 39200 on the high scale and connect it to each end of the wire being tested. Twist the wire gently while watching J 39200. 3. If J 39200 reads above 30,000 ohms (no matter how long the wire is), or fluctuates from infinity any value, replace the wire. 4. If the resistance of any wire is not within the following ranges, replace the wire being tested. - 0 to 381 mm (0 to 15 in.) wire - 3,000 to 10,000 ohms. - 381 mm to 635 mm (15 in. to 25 in.) wire - 4,000 to 15,000 ohms. - 635 mm to 889 mm (25 in. to 35 in.) wire - 6,000 to 20,000 ohms. - Longer wire - should measure about 5,000 to 10,000 ohms per foot. Page 2482 Spark Plug: Application and ID Spark Plug Coding Spark Plug Codeing Legend DESCRIPTION Resistor-type, tapered-seat spark plugs are used on this engine. No gasket is used on these spark plugs. A dot before the spark plug code or the letter "C" after the number in the code indicates the spark plug has a copper core. Refer to Specification / Mechanical or to the vehicle emissions control information label for correct gap information. Page 1908 Fuse: Application and ID Convenience Center Convenience Center Page 1184 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3758 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3821 Fig.2-Symbols (Part 2 Of 3) Page 2050 onto the subject vehicle. - After match mounting, the tire/wheel assembly must be rebalanced. If match mounting tires to in-spec wheels produces assembly values higher than these, tire replacement may be necessary. Replacing tires at lower values will probably mean good tires are being condemned. Because tires can sometimes become temporarily flat-spotted, which will affect force variation, it is important that the vehicle be driven at least 16 km (10 mi) prior to measuring. Tire pressure must also be adjusted to the usage pressure on the vehicle's tire placard prior to measuring. Most GM vehicles will tolerate radial force variation up to these levels. However, some vehicles are more sensitive, and may require lower levels. Also, there are other tire parameters that equipment such as the Hunter GSP9700 cannot measure that may be a factor. In such cases, TAC should be contacted for further instructions. Important - When mounting a GM wheel to a wheel balancer/force variation machine, always use the wheel's center pilot hole. This is the primary centering mechanism on all GM wheels; the bolt holes are secondary. Usually a back cone method to the machine should be used. For added accuracy and repeatability, a flange plate should be used to clamp the wheel onto the cone and machine. This system is offered by all balancer manufacturers in GM's dealer program. - Any type of service equipment that removes tread rubber by grinding, buffing or truing is NOT recommended, and may void the tire warranty. However, tires may have been ground by the tire company as part of their tire manufacturing process. This is a legitimate procedure. Steering Wheel Shake Worksheet When diagnosing vibration concerns, use the following worksheet in conjunction with the appropriate Vibration Analysis-Road testing procedure in the Vibration Correction sub-section in SI. 4L60-E (M30) Transmission Fluid Pressure Sensor/Switch: Testing and Inspection 4L60-E (M30) Transmission Circuit Check Transmission Range (TR) Pressure Switch Assembly Circuit Check Page 832 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1931 Underhood Fuse - Relay Center Page 1481 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3113 Fig.2-Symbols (Part 2 Of 3) Page 1966 1. Use a proper hand reamer, carbide cutter or drill bit to ream the puncture channel from the inside of the tire in order to clean the injury. 2. Remove steel wires protruding above the liner surface to prevent damage to the repair unit. 3. Consult your repair material supplier for recommended reaming tool(s). Fill the Injury 1. It is necessary to fill the injury channel to provide back up for the repair unit and to prevent moisture from entering the tire fabric and steel wires. 2. (For combination repair/plug units skip this step.) Cement the injured channel and fill the injury from the inside of the tire with the repair plug per repair material manufacturer's recommendations. Without stretching the plug, cut the plug off just above the inside tire surface. 3. Consult your repair material supplier for proper repair material selection. Repair Unit Selection Important Do not install the repair unit in this step. Page 2708 Fig.2-Symbols (Part 2 Of 3) Page 393 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 1440 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1665 Spark Plug Wire: Service and Repair SERVICE CAUTIONS 1. Twist boots one-half turn before removing. 2. When removing the boot, do not use pliers or other tools that could tear the boot. 3. Do not force anything between the wire and the boot, or through the silicone jacket of the wiring. 4. Do not pull on the wires to remove the boot. Pull on the boot or use a tool designed for this purpose. 5. Special care should be used when installing spark plug boots to ensure the metal terminal within the boot is fully seated on the spark plug terminal and the boot has not moved on the wire. SPARK PLUG WIRE REPLACEMENT Spark plug wire routings must be kept intact during service and followed exactly when spark plug wires have been disconnected or when replacement of the spark plug wires is necessary. Failure to route the spark plug wires properly can lead to radio noise and crossfiring of the spark Page 957 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2838 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: C1 Heater And A/C Control Select SW (C1) Page 1832 Fluid - A/T: Fluid Type Specifications Fluid Type ............................................................................................................................................ ................................................................. Dexron III Page 564 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 453 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 793 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3005 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1263 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 478 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 944 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 2882 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3634 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Diagram Information and Instructions Camshaft Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Engine, A/T - Shift/Driveability Concerns/MIL ON Air Filter Element: All Technical Service Bulletins Engine, A/T - Shift/Driveability Concerns/MIL ON Bulletin No.: 04-07-30-013B Date: February 01, 2007 INFORMATION Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007 HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X Supercede: This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 04-07-30-013A (Section 07 - Transmission/Transaxle). The use of an excessively/over-oiled aftermarket, reusable air filter may result in: Service Engine Soon (SES) light on Transmission shift concerns, slipping and damaged clutch(es) or band(s) Engine driveability concerns, poor acceleration from a stop, limited engine RPM range The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur. When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared to a like vehicle with an OEM air box and filter under the same driving conditions to verify the concern. The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty. If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and the air induction hose for contamination of oil prior to making warranty repairs. Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not considered to be warrantable repair items. Page 3753 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3919 Serial Data: Symptom Related Diagnostic Procedures Scan Tool Will Not Communicate With Components (Part 1 Of 2) Scan Tool Will Not Communicate With Components (Part 2 Of 2) Page 1407 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3091 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Capacity Specifications Fluid - M/T: Capacity Specifications NV4500 Manual Transmission ............................................................................................................ ................................................... 3.78 liters (4 quarts) NV3500 Manual Transmission ............................................................................................................................................................. 2.0 liters (2.2 quarts) Page 2888 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Diagram Information and Instructions Air Flow Meter/Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Specifications Spark Plug: Specifications Spark Plug Gap ................................................................................................................................... ............................................. 0.90 mm (0.035 inches) Spark Plug Torque ............................................................................................................................... ...................................................... 15 Nm (11 lb. ft.) Spark Plug Type .................................................................................................................................. .............................................................. AC CR43TS NOTE: Check the gap specifications found on the Emissions Control Label. If the gap is different from what is listed here, use the information on the label. Specifications Manifold Absolute Pressure (MAP) Sensor: Specifications 1,000 to 2,000 Feet ............................................................................................................................. ........................................................... 3.6 to 5.2 Volts 2,000 to 3,000 Feet ........................................ ................................................................................................................................................ 3.5 to 5.1 Volts 3,000 to 4,000 Feet .............................................................................................................. .......................................................................... 3.3 to 5.0 Volts 4,000 to 5,000 Feet ......................... .............................................................................................................................................................. . 3.2 to 4.8 Volts 5,000 to 6,000 Feet .................................................................................................. ...................................................................................... 3.0 to 4.6 Volts 6,000 to 7,000 Feet ............. .............................................................................................................................................................. ............. 2.9 to 4.5 Volts 7,000 to 8,000 Feet ...................................................................................... .................................................................................................. 2.8 to 4.3 Volts 8,000 to 9,000 Feet . .............................................................................................................................................................. ......................... 2.6 to 4.2 Volts 9,000 to 10,000 Feet ........................................................................ .............................................................................................................. 2.5 to 4.0 Volts Page 174 PCM Connector Pin-Out Page 3416 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 532 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3452 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2820 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1431 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3716 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 475 Clutch Switch: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical I/P Fuse Block Fuse Block: Application and ID I/P Fuse Block I/P Fuse Block Page 3171 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3072 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1186 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3006 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 1034 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3328 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Locations Engine Arming Sensor Impact Sensor: Service and Repair Arming Sensor Prior to performing replacement procedures, disarm air bag system. Refer to, Service and Repair/ Air Bag System Disarming & Air Bag System Arming. Refer to, / Specifications/ Mechanical for torque values when installing components. All sensors and mounting bracket bolts must be carefully torqued to assure proper operation. Never power up the air bag system when any sensor is not rigidly attached to the vehicle, since the sensor could be activated when not attached, causing air bag deployment. 1. disconnect sensor electrical connector from retainer, remove Connector Position Assurance (CPA) lock from connector, then disconnect connector. 2. Remove sensor mounting bolts and sensor from vehicle. 3. Reverse procedure to install. Page 3191 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2970 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 823 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Service and Repair Water Pump: Service and Repair Water Pump Replacement. 7.4L/V8-454 Engine 1. Disconnect battery ground cable. 2. Drain coolant from radiator. 3. Remove upper fan shroud. 4. Remove drive belt. 5. Remove fan assembly from engine. 6. Lower radiator and heater hose from the water pump. 7. Remove bypass hose. 8. Remove water pump attaching bolts and water pump, Fig. 16. 9. Reverse procedure to install. Tighten water pump attaching bolts to specifications. Page 667 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 103 C103: Cruise Control Module Page 3099 Knock Sensor: Description and Operation PURPOSE: The Knock Sensor (KS) is used to detect engine detonation (ping). OPERATION A 5 volt reference is applied to the knock sensor which has an internal resistance of about 3900 ohms. This resistance will lower the applied voltage to about half or 2.5 volts. When a knock is present, a small AC voltage is produced by the knock sensor and transmitted to the control module riding on top of the already existing 2.5 volts. An AC voltage monitor inside the control module will detect the knock and trigger the control module to start retarding the spark incrementally. A control module (ECM or PCM) is used in conjunction with one or two knock sensors to control detonation. A KS module will be found on ECM applications. On PCM application no KS module will be found as it is internal to the control module. Capacity Specifications Fluid - A/T: Capacity Specifications 4L60E Automatic Transmission Drain and Refill .................................................................................................................................... ............................................. 4.7 liters (5 quarts) Complete Overhaul ................................................. ....................................................................................................................... 10.6 liters (11 quarts) 4L80E Automatic Transmission Drain and Refill .................................................................................................................................... .......................................... 7.3 liters (7.7 quarts) Complete Overhaul ................................................. .................................................................................................................... 12.8 liters (13.5 quarts) Page 1191 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 2879 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3019 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 537 Cruise Control Switch: Service and Repair 1. Disconnect battery ground cable. Fig. 38 Cruise Control Switch Replacement. 2. Remove cruise control switch protector cover, Fig. 38. 3. Disconnect switch electrical connector, then remove the switch and cruise control wire. 4. Reverse procedure to install. Page 194 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Valve Clearance Specifications Valve Clearance: Specifications Valve Clearance Specifications Engine Liter/CID .................................................................................................................................. ........................................................... 7.4L/V8-454 All specifications given in inches. Stem Diameter Std. Intake ................................................................................................................................................... ...................................................... 0.3715-0.3722 Exhaust ................................................................ ...................................................................................................................................... 0.3715-0.3722 Maximum Tip Refinish ......................................................................................................................... ........................................................................ [03] Face Angle .......................................................... ....................................................................................................................................................... 45 deg. Margin [01] Intake ................................................................................................................................................... .................................................................. 0.0315 Exhaust ................................................................. .................................................................................................................................................. 0.0315 Valve Lash ........................................................................................................................................... ........................................................................... [06] [01] Minimum. [03] Grind only enough to provide true surface. After grinding valve stems, ensure sufficient clearance remains between rocker arm & valve spring cap or rotator. [06] Torque rocker arm bolt to 40 ft. lbs Diagram Information and Instructions Fuel Pump Relay: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3318 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 759 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 2300 For K trucks with 8600 # GVW's and below, a new lower control arm is available featuring an opening under the front axle outboard boot (Figure 1). The opening should prevent the build-up of debris by allowing the debris to fall through. The new lower control arm went into production after the beginning of the 1995 model year starting with the VIN breakpoints listed above. Additionally, for vehicles operating in severe usage environments (snow plows, mines, etc.) a front axle seal cover is available and can be used in conjunction with the new lower control arm (Figure 2). The purpose of this protective device is to sweep as much debris as possible from the lower control arm. This should extend the life of the front axle seal. It should be noted however that the protective seal cover WILL, during its useful life, take on a ragged appearance while still adequately protecting the drive axle seal. The device is functioning as long as the fabric continues to sweep debris from the lower control arm. K - Models with GVW's Above 8600 # For K-models with GVW's above 8600 # a front axle seal cover is available (Figure 2). The purpose of this protective device is to sweep as much debris as possible from the lower control arm. This should extend the life of the front axle seal. It should be noted however that the protective seal cover WILL during its useful life, take on a ragged appearance while still adequately protecting the drive axle seal. The device is functioning as long as the fabric continues to sweep debris from the lower control arm. Page 2620 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 476 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3585 Distributor: Testing and Inspection INSPECT 1. Distributor cap for cracks or tiny holes. Replace the cap if it is damaged or worn. 2. Metal terminals in the distributor cap for corrosion. Scrape them clean with a knife or replace the cap. 3. Rotor for wear or burning at the outer terminal. The presence of carbon on the terminal indicates rotor wear and the need for replacement. 4. Distributor shaft for shaft-to-bushing looseness. Insert the shaft in the distributor housing. If the shaft wobbles, replace the distributor housing and/or shaft. 5. Distributor housing for cracks or damage. MEASURE Tools Required J 24642-F Module Tester. Electrical performance of the module. The module can only be tested with an approved module tester, such as J 24642-F. Follow the directions that come with the tester. Page 2965 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 253 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3077 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 218 Idle/Throttle Speed Control Unit: Service and Repair Throttle Body Assembly (Model 220) REMOVAL: - Remove the Idle Speed Control (ISC) Actuator and vacuum hose. - Remove ISC Actuator. INSTALLATION: - Install the ISC actuator and screws. - Connect vacuum hose. - Set activated idle speed. Refer to Adjustment Procedures. Engine - Cold Knock, Replace Oil Filter/Bearings/PROM Oil Filter: Customer Interest Engine - Cold Knock, Replace Oil Filter/Bearings/PROM File In Section: 6 - Engine Bulletin No.: 37-61-05A Date: October, 1995 Subject: Cold Engine Knock (Replace Oil Filter/Bearings/PROM) Models: 1990-95 Chevrolet and GMC Truck C/K, R/V, S/T, M/L, G, P Models 1991-92 Oldsmobile Bravada with 4.3L (VIN Z - RPO LB4), 5.7L (VIN K - RPO L05), 7.4 (VIN N - RPO L19) Engine This bulletin is being revised to add the 1995 model year information. Please discard Corporate Bulletin Number 37-61-05 (Section 6 - Engine). Condition Some late model truck engines have been reported to exhibit "cold knock" on start up. "Cold Knock" usually occurs after the vehicle has been completely warmed up, then parked for 8 or more hours in ambient temperatures of 35° F or less. "Cold knock" can be separated into three distinct categories. 1. Short Duration - Harsh, deep metallic knock that usually lasts from 1 to 10 seconds. Generally classified as a bearing or rod knock. 2. Valve Train - Light clatter, tick or click that may last up to 1 minute. 3. Piston Slap - Metallic knock that occurs only under load. Piston slap may last as long as 5 minutes. Correction Category A: Short Duration Knock This matrix describes the repair for each affected model year and engine. Specific information for each affected model year and engine is supplied. Page 168 PCM Connector Pin-Out Page 315 Specifications Spark Plug Wire: Specifications RESISTANCE VALUES 0-15 inch cable .................................................................................................................................... ....................................... 3,000 - 10,000 ohms. 15-25 inch cable .................................................................................................................................. ....................................... 4,000 - 15,000 ohms. 25-35 inch cable .................................................................................................................................. ....................................... 6,000 - 20,000 ohms. NOTE: Longer wires should measure about 5,000 to 10,000 ohms per foot. Page 1312 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 2922 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 860 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1507 Transmission Range (TR) Pressure Switch Assembly Circuit Check CIRCUIT DESCRIPTION The Transmission Range (TR) switch assembly consists of five pressure switches (two normally closed and three normally open), and a Transmission Fluid Temperature (TFT) sensor combined into one unit and mounted on the valve body. The Powertrain control Module (PCM) supplies battery voltage to each range signal. By grounding one or more of these circuits through various combinations of the pressure switches, the PCM detects what manual valve position has been selected by the vehicle operator. With ignition "ON" and engine "OFF," P/N will be indicated. When transmission electrical connector is disconnected, the ground potential for the three range signals to the PCM will be removed, and with ignition "ON," D2 will be indicated. DTC CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic charts. 1. This test checks the indicated range signal to the manual valve position actually selected. 2. This test checks for correct voltage from the PCM to the transmission external connector. 3. This test checks for a short to ground from the PCM to the transmission external connector in any one of the three circuits. A/B/C Range Combinations DIAGNOSTIC AIDS Refer to accompanying chart for various A/B/C range combinations. Check all wiring connectors for proper terminal tension. For current DTC 28, range signal will default to "D4" while A/B/C range values continue to read actual "TR Pressure Switch Output" for each range selection. Refer to "TR Pressure Switch Assembly Resistance Check" or "Functional Test Procedure" for further information. See: Powertrain Management/Computers and Control Systems/Testing and Inspection Page 411 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 462 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 1452 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Specifications Idle Air Control Valve: Specifications Terminals "A" to "B" ............................................................................................................................. ......................................................... 40 to 80 Ohms Terminals "C" to "D" ............................................................................................................................ .......................................................... 40 to 80 Ohms Terminals "B" to "C" ............................................................................................................................. .......................................................... Infinite Ohms Terminals "A" to "D" ............................................................................................................................. .......................................................... Infinite Ohms Page 3131 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Instruments - Excessive Fuel Gauge Fluctuation Fuel Gauge Sender: All Technical Service Bulletins Instruments - Excessive Fuel Gauge Fluctuation File In Section: 8 - Chassis/Body Electrical Bulletin No.: 76-83-05 Date: September, 1997 Subject: Excessive Fuel Gauge Fluctuation (Install Fuel Level Damper Kit) Models: 1995-97 Chevrolet and GMC C/K 4 Door Utility Models Condition Some owners may comment about excessive fuel gauge needle fluctuation when making turns or braking with less than a half tank of fuel. Correction Install fuel level damper module kit P/N 12167652 following the procedure described on the instruction sheets included with the kit. Parts Information P/N Description Qty 12167652 Module Kit, Fuel Level Damper 1 Parts are currently available from GMSPO. Warranty Information For vehicles repaired under warranty, use: Labor Op Description Labor Time N4844 Module, Anti-slosh - Install 0.8 hr Important: Labor operation is coded to base vehicle coverage in the warranty system. Page 3352 Throttle Position Sensor: Locations Component View Throttle Position (TP) Sensor The Throttle Position (TP) Sensor is attached to the right hand side of the throttle body. Page 1413 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2836 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1058 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 2554 Radiator Cooling Fan Motor: Description and Operation When the Ignition Switch is on the RUN, BULB TEST or START positions, voltage is applied to the coil (power side) of the Auxiliary Cooling Fan Relay through the IGN E Fuse. Ground is supplied to the coil (ground side) of the Auxiliary Cooling Fan Relay through either the Auxiliary Cooling Fan Temperature Switch, High Pressure Switch or the A/C Controller. When either of the above three components provide ground to the coil of the Auxiliary Cooling Fan Relay, it energizes and the contacts close. Voltage is applied through the AUX FAN Fuse and the closed contacts of the Auxiliary Cooling Fan Relay to the Auxiliary Cooling Fan Motor. Since the Auxiliary Cooling Fan Motor is grounded at G112, it runs. Page 2025 10. Align the inscribed mark on the tire with the valve stem on the wheel. 11. Reinstall the Tire Pressure Sensor. Refer to Tire Pressure Sensor installation procedure in SI. 12. Mount the tire on the wheel. Refer to Tire Mounting and Dismounting. 13. Pressurize the tire to 276 kPa (40 psi) and inspect for leaks. 14. Adjust tire pressure to meet the placard specification. 15. Balance the tire/wheel assembly. Refer to Tire and Wheel Assembly Balancing - Off-Vehicle. 16. Install the tire and wheel assembly onto the vehicle. Refer to the appropriate service procedure in SI. Parts Information Warranty Information (excluding Saab U.S. Models) Important The Silicone - Adhesive/Sealant comes in a case quantity of six. ONLY charge warranty one tube of adhesive/sealant per wheel repair. For vehicles repaired under warranty, use: One leak repair per wheel. Warranty Information (Saab U.S. Models) For vehicles repaired under warranty, use the table above. Disclaimer Locations Diagnostic Connector - Fuel Pump: Locations FUEL PUMP PRIME CONNECTOR The Fuel Pump Prime Connector is located in the Instrument Panel (I/P) harness, approximately 20 cm into the Fuse-Relay Center. NOTE: The OEM service manual does not provide a location image for this component. Page 942 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Specifications Connecting Rod Bearing: Specifications Connecting rod bearing inserts are available in standard size and undersizes of .001 inch, .002 inch, .010 inch and .020 inch. The bearings can be replaced without removing the rod assembly by removing the cap and replacing the upper and lower halves of the bearing. Page 2831 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 1272 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 935 Fig.2-Symbols (Part 2 Of 3) Page 683 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 401 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3186 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 785 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1717 Disclaimer Page 3169 Fig.2-Symbols (Part 2 Of 3) Harness View Engine Close Couple Catalytic Converter Service and Repair Vehicle Lifting: Service and Repair Fig. 13 Vehicle Lift Points. Fig. 13 Vehicle Lift Points. Page 1969 Some run flat tires, such as the Goodyear Extended Mobility Tire (EMT) used on the Corvette, may require more than 275 kPa (40 psi) to seat the bead. In such a case, a tire safety cage must be used. Consult the tire manufacturer for its individual repair policy. Final Inspection 1. After remounting and inflating the tire, check both beads, the repair and the valve with a water and soap solution in order to detect leaks. 2. If the tire continues to lose air, the tire must be demounted and reinspected. 3. Balance the tire and wheel assembly. Refer to Tire and Wheel Assembly Balancing - OFF Vehicle. For additional tire puncture repair information, contact: Rubber Manufacturers Association (RMA) Disclaimer Page 993 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 2083 *This product is currently available from 3M. To obtain information for your local retail location please call 3M at 1-888-364-3577. **This product is currently available from Meguiars (Canada). To obtain information for your local retail location please call Meguiars at 1-800-347-5700 or at www.meguiarscanada.com. ^ This product is currently available from Tri-Peek International. To obtain information for your local retail location please call Tri-Peek at 1-877-615-4272 or at www.tripeek.com. Disclaimer Page 566 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Locations Powertrain Control Module (PCM) Page 2274 1993 to 1995 L05 VIN K Install the appropriate check valve oil filter P/N 25160561 (PF1218 for two-wheel C-series and P/N 12555891 (FRAM PH3980) for four-wheel drive K-series). If the oil filter does not cure the condition, install the appropriate calibration from the table (calibrations are available for some 1993 and 1994 L05 applications). All calibrations are for light duty vehicles equipped with 4L60-E (M30) transmissions (no heavy duty emission/4L80-E calibrations are available). If a calibration is not offered or does not cure the short duration cold knock condition, install the appropriate main bearings as determined by the procedure. 1990-94 L19 VIN N Page 1275 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1065 Throttle Position Sensor: Service and Repair Throttle Position (TP) Sensor NOTE: Since TP configurations can be mounted interchangeably, be sure to order the correct one for your engine with the identical part number of the one being replaced. REMOVE OR DISCONNECT 1. Electrical connector. 2. Two TP sensor attaching screw assemblies. 3. TP sensor from throttle body assembly. NOTE: The TP sensor is an electrical component and must not be soaked in any liquid cleaner or solvent, as damage may result. INSTALL OR CONNECT 1. With throttle valve in normally closed position, install TP sensor on throttle shaft and rotate counter clockwise to align mounting hole. 2. TP sensor attaching screw assemblies, precoated with appropriate thread.locking compound. Tighten Screw assemblies to 2.0 Nm (18.0 lb. in.). 3. Electrical connector. 4. Check for TP sensor output as follows: ^ Connect scan tool scanner to read TP sensor output voltage. ^ With ignition "ON" and engine stopped, TP sensor voltage should be less than 0.85 volt. If more than 0.85 volt, replace TP sensor. Page 3484 Knock Sensor Page 3261 Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 878 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 102 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Locations Engine Page 3938 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3793 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 663 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3771 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 3196 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Engine - Drive Belt Misalignment Diagnostics Drive Belt: Technical Service Bulletins Engine - Drive Belt Misalignment Diagnostics INFORMATION Bulletin No.: 08-06-01-008A Date: July 27, 2009 Subject: Diagnosing Accessory Drive Belt / Serpentine Belt Noise and Availability and Use of Kent-Moore EN-49228 Laser Alignment Tool - Drive Belt Models: 2010 and Prior GM Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3 Vehicles 2009 and Prior Saab 9-7X Supercede: This bulletin is being revised to add a model year and update the Tool Information. Please discard Corporate Bulletin Number 08-06-01-008 (Section 06 - Engine). Background Several aftermarket companies offer laser alignment tools for accessory drive systems that can be very helpful in eliminating drive belt noise as a result of misaligned pulleys. Typically pricing ranges from $160 - $200. EN-49228 Laser Alignment Tool - Drive Belt The GM Tool program has now made available a competitive, simple to use and time-saving laser tool to assist in achieving precise alignment of the drive belt pulleys. This optional tool removes the guesswork from proper pulley alignment and may serve to reduce comebacks from: - Drive Belt Noise - Accelerated Drive Belt Wear - Drive Belt Slippage Instructions The instructions below are specific only to the truck Gen IV V-8 family of engines. These instructions are only for illustrative purposes to show how the tool may be used. Universal instructions are included in the box with the Laser Alignment Tool - Drive Belt. Caution - Do not look directly into the beam projected from the laser. - Use caution when shining the laser on highly polished or reflective surfaces. Laser safety glasses help reduce laser beam glare in many circumstances. - Always use laser safety glasses when using the laser. Laser safety glasses are not designed to protect eyes from direct laser exposure. 1. Observe and mark the serpentine belt orientation. Page 202 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2729 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3590 Spark Plug: Service Precautions WARNING: If you smoke while handling coated spark plugs, wear gloves to prevent transfer of coating to cigarette and subsequent burning of coating. Always wash hands after handling coated plugs. CAUTION: Observe service precautions: - Allow engine to cool BEFORE removing spark plugs. Attempting to remove spark plugs from a hot engine may cause plug to seize, causing damage to cylinder head threads. - Clean spark plug recess area BEFORE removing plug. Failure to do so can result in engine damage due to dirt or foreign material entering cylinder head, or in contamination of cylinder head threads. Contaminated threads may prevent proper seating of new plug. - Use only spark plugs specified for use in the vehicle. DO NOT install spark plugs that are either "hotter" or "colder" than those specified for the vehicle. Installing plugs of another type can severely damage the engine. Page 2341 Oil Pressure Gauge: Testing and Inspection Gauge Reads High 1. Disconnect lead from sensor, then turn ignition switch to the ON position and ground lead. 2. If gauge reads low, replace sensor. 3. If gauge reads high, locate and repair open circuit between sensor and gauge. Page 2474 Distributor: Specifications Distributor Hold Down Bolt .................................................................................................................. ................................................... 27 Nm (20 lbs. ft.) Page 2202 Crankshaft: Specifications Crankshaft Dimensions Engine Liter/CID .................................................................................................................................. ........................................................... 7.4L/V8-454 All specifications given in inches. Crankshaft Journals Main Bearing Journal Diameter .............................................................................................................................................................. 2.7482-2.7489 Connecting Rod Journal Diameter .......................................................................................................................................................... 2.1991-2.1996 Maximum Out Of Round All ......................................................................................... ...................................................................................... 0.0010 Runout Service Limit ........................ .............................................................................................................................................................. .......... [02] Bearing Clearance Main Bearings ...................................................................................................................................... ...................................................................... [14] Connecting Rod Bearings ...................................... ................................................................................................................................... 0.0011-0.0029 Thrust Bearing ..................................................................................................................................... ..................................................... 0.0050-0.0110 Connecting Rods Pin Clearance [12] ............................................................................................................................... ...................................................... 0.0021-0.0031 Side Clearance ..................................................... ...................................................................................................................................... 0.0130-0.0230 [02] If main journals are misaligned, crankshaft is bent & must be replaced. [12] Interference fit. [14] Except No. 5, 0.0017-0.0030 inch; No. 5, 0.0025-0.0038 inch. Crankshaft Rotation Timing Marks and Indicators: Locations Crankshaft Rotation Crankshaft Rotation (Typical Crankshaft Pulley) Crankshaft rotation is clockwise when viewed from in front of the crankshaft pulley as shown in the generic image. Page 1125 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3023 Coolant Temperature Sensor/Switch (For Computer): Service and Repair Engine Coolant Temperature (ECT) Sensor NOTE: Care must be taken when handling engine coolant temperature sensor. Damage to the Engine Coolant Temperature (ECT) sensor will affect proper operation of the fuel injection system. REMOVAL 1. Disconnect negative battery cable. 2. Drain cooling system below level of sensor. 3. Disconnect electrical connector. 4. Remove ECT sensor. INSTALLATION 1. Install sensor in engine. 2. Connect electrical connector. 3. Refill cooling system. 4. Connect negative battery cable. Page 2770 Catalytic Converter: Locations Three Way Catalytic Converter Page 1370 The existing labor operation (E7200) has been changed to include "Add" conditions for cylinders that will not rotate. New Tumblers New tumblers are available from GMSPO for recoding lock cylinders that use double-sided reversible keys. These new tumblers should be used immediately and information about the disposition of original tumblers will be provided by GMSPO. Figure 1 shows the new tumbler profile. The shaded area was part of the original tumbler profile, and is removed on the new tumblers. The new part numbers for the tumblers are as follows: Part No. 2852732 = Tumbler # 1 Part No. 2852733 = Tumbler # 2 Part No. 2852734 = Tumbler # 3 Part No. 2852735 = Tumbler # 4 Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. New Procedures For Seized/Won't Rotate Column Mounted Ign. CYL. Page 1028 Throttle Position Sensor: Locations Component View Throttle Position (TP) Sensor The Throttle Position (TP) Sensor is attached to the right hand side of the throttle body. Specifications Intake Air Temperature Sensor: Specifications Torque Valve Torque Valve Induction Air Sensor 44 in.lb Instruments - Fuel Gauge Indicates Empty When Not Fuel Gauge Sender: All Technical Service Bulletins Instruments - Fuel Gauge Indicates Empty When Not File In Section: 8 - Chassis/Body Electrical Bulletin No.: 76-83-03A Date: June, 1998 Subject: Fuel Gauge Indicates Empty with 7-8 Gallons (30 Liters) Left in Tank (Replace Fuel Level Sensor Float Arm Assembly) Models: 1995-97 Chevrolet and GMC C/K 4 Door Models Built Prior to VIN Breakpoints: Models VIN Breakpoints Chevrolet VJ355982 GMC VJ724930 This bulletin is being revised to change the labor operation number. Please discard Corporate Bulletin Number 76-83-03 (Section 8 - Chassis/Body Electrical). Condition Some owners may comment that the fuel gauge indicates empty after only going 200 to 250 miles, and they are only able to put approximately 23 gallons or less of fuel in the 30 gallon tank. Cause The Fuel Level Indication System was designed with excessive empty reserve. The Fuel Level Sender will be labeled with Broadcast code "TCB", (see Figure 1). Vehicles built after December 14, 1996, have the revised Float Arm Assembly. Correction Page 3618 Air Flow Meter/Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1439 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3819 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1497 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 3097 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 151 Relay Box: Application and ID Underhood Fuse/Relay Center Ignition System - Distributor Is Now Repairable Distributor: Technical Service Bulletins Ignition System - Distributor Is Now Repairable CHEVROLET 71-65-40 Issued: 05/01/97 SMU - SECTION 6E - REVISED ENHANCED IGNITION SYSTEM DESCRIPTION AND OPERATION SUBJECT: SERVICE MANUAL UPDATE - SECTION 6E - ENGINE CONTROLS REVISED ENHANCED IGNITION SYSTEM DESCRIPTION AND OPERATION MODELS: 1995-97 CHEVROLET AND GMC S/T, M/L, C/K, GMT600, P MODELS 1996-97 OLDSMOBILE BRAVADA WITH 4.3L, 5.0L, 5.7L, 7.4L ENGINE (VINS W, M, R, J - RPOS L35, L30, L31, L29) THIS BULLETIN IS BEING ISSUED TO INFORM TECHNICIANS OF A REVISION TO THE ENHANCED IGNITION SYSTEM DESCRIPTION AND OPERATION. THE DISTRIBUTOR IS NOW REPAIRABLE. TECHNICIANS WILL BE REFERRED TO DISTRIBUTOR OVERHAUL IN ENGINE ELECTRICAL FOR PROPER REPAIR AND REPLACEMENT OF ALL COMPONENTS. Page 3118 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 962 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 1234 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Harness View Engine Page 1504 Fluid Pressure Sensor/Switch: Description and Operation 4L80-E (MT1) Transmission TRANSMISSION FLUID PRESSURE SWITCH ASSEMBLY A gear range sensing device call an Transmission Fluid Pressure Switch Assembly (PSA) is used by the PCM/TCM in order to sense what gear range has been selected by the vehicle operator. The PSA is located on the valve body and consists of five pressure switches combined into one unit. The PCM/TCM applies system voltage to the PSA on three separate wires. These three circuits are either grounded or open, depending on which gear range has been selected, and on which combination of the five switches have pressure applied to them. When the vehicle is in PARK, with the key ON and the engine OFF, the normal state of the PSA will be Drive 2. When the key is ON and the engine is running, the normal state of the PSA will be in PARK/NEUTRAL. There are two possible combinations of the switches within the pressure switch manifold that do not represent an actual gear range. If the PCM/TCM detects either of these combinations for more that 0.5 seconds, Code 28 will set. Code 28 will not set, however, if a valid gear range combination appears at the wrong time. While Code 28 is present, the PCM/TCM will take the following actions: Assume Drive 4 for shift pattern control - Use Drive 2 pressure table - Inhibit 4th gear operation - Inhibit TCC operation If the PSA resumes normal functioning, the transmission will resume normal operation after the next ignition cycle Other possible default codes: 68. Page 3081 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3174 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 1930 Relay Box: Application and ID Underhood Fuse/Relay Center Page 1051 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Diagram Information and Instructions Crankshaft Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1333 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 544 Fig.2-Symbols (Part 2 Of 3) Service and Repair Engine Mount: Service and Repair Fig. 1 Front Engine Mount FRONT MOUNTS When raising or supporting the engine for any reason, do not use a jack under the oil pan, any sheet metal or crankshaft pulley. Due to the small clearance between the oil pan and oil pump screen, jacking against the oil pan may cause it to be bent against the pump screen, resulting in a damaged oil pickup unit. 1. Using a jack, support engine. 2. Remove engine mount through bolt and nut, Fig. 1. Raise engine only enough for sufficient clearance. Check for interference between rear of engine and the dash panel which could cause distributor damage. 3. Remove engine mount assembly bolts, nuts and washers. 4. Remove mount assembly. 5. Reverse procedure to install. REAR MOUNTS When raising or supporting the engine for any reason, do not use a jack under the oil pan, any sheet metal or crankshaft pulley. Due to the small clearance between the oil pan and oil pump screen, jacking against the oil pan may cause it to be bent against the pump screen, resulting in a damaged oil pickup unit. 1. Support rear of engine to relieve the weight on the rear mounting. 2. Remove mount to crossmember nuts and washers. 3. Remove mount to transmission attaching bolts and washers. Raise rear of engine only enough to permit removal of the mount. 4. Reverse procedure to install. Page 3092 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2900 Fuel Pump Relay: Testing and Inspection RESULTS OF INCORRECT FUEL PUMP RELAY OPERATION - An inoperative fuel pump relay can result in long cranking times, particularly if the engine is cold. As a backup system to the fuel pump relay, the fuel pump is also turned "ON" by an oil pressure switch. The oil pressure switch will turn "ON" the fuel pump as soon as oil pressure reaches about 28 kPa (4 psi). Page 1192 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Dana/Spicer Full Floating Axle Wheel Bearing: Adjustments Dana/Spicer Full Floating Axle REAR WHEEL BEARINGS ADJUSTMENT Ensure the brakes are completely released and do not drag. Check wheel bearing play by grasping the tire at the top and pulling and pushing back and forth, or by using a pry bar under the tire. If the wheel bearings are properly adjusted, movement of the brake drum in relation to the brake flange plate will be barely noticeable and the wheel will turn freely. If the movement is excessive, adjust the bearings as follows: 1. Back off attaching nut until just loose, but not more than one slot of the lock or the axle spindle using wheel bearing nut wrench tool No. J-2222-C or equivalent. 2. Align adjusting nut slot with keyway in the axle spindle. Page 803 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 966 MAP Sensor Circuit CIRCUIT DESCRIPTION The Manifold Absolute Pressure (MAP) sensor measures the changes in the intake manifold pressure which result from engine load (intake manifold vacuum) and rpm changes; and converts these into a voltage output. The PCM sends a 5 volt reference voltage to the MAP sensor. As the manifold pressure changes, the output voltage of the sensor also changes. By monitoring the sensor output voltage, the PCM knows the manifold pressure. At lower pressure output voltage will be about 1 to 2 volts at idle. While at higher pressure or at Wide Open Throttle (WOT) output voltage will be about 4 to 4.8 volts. The MAP sensor is also used, under certain conditions, to measure barometric pressure, allowing the PCM to make adjustments for different altitudes. The PCM uses the MAP sensor to control fuel delivery and ignition timing. CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic chart. IMPORTANT: Be sure to use the same diagnostic test equipment for all measurements. 1. Checks MAP sensor output voltage to the PCM. This voltage, without engine running, represents a barometer reading to the PCM. ^ When comparing Tech 1 scan readings to a known good vehicle, it is important to compare vehicles that use a MAP sensor having the same color insert or having the same "Hot Stamped" number. Refer to figures in chart. 2. Applying 34 kPa (10" Hg) vacuum to the MAP sensor should cause the voltage to change. Subtract second reading from the first. Voltage value should be greater than 1.5 volts. Upon applying vacuum to the sensor, the change in voltage should be instantaneous. A slow voltage change indicates a faulty sensor. 3. Check vacuum hose to sensor for leaking or restriction. Be sure that no other vacuum devices are connected to the MAP hose. NOTE: Make sure electrical connector remains securely fastened. 4. Disconnect sensor from bracket and twist sensor by hand (only) to check for intermittent connection. Output changes greater than 0.1 volt indicate a bad connector or connection. If OK, replace sensor. Page 3887 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 558 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Service and Repair Timing Chain: Service and Repair Fig. 8 Timing Mark Alignment 1. Remove Front Cover. 2. Remove crankshaft oil slinger. 3. Crank engine until 0.0 marks on sprockets are in alignment, Fig. 8. 4. Remove three camshaft to sprocket bolts. 5. Remove camshaft sprocket and timing chain together. Sprocket is a light press fit on camshaft for approximately 1/8 inch. If sprocket does not come off easily, a light blow with a plastic hammer on the lower edge of the sprocket should dislodge it. 6. If crankshaft sprocket is to be replaced, remove it with a gear puller. Install new sprocket, aligning key and keyway. 7. Install chain onto camshaft sprocket. Hold sprocket with chain hanging vertically, then align marks on sprockets as shown, Fig. 8. The valve timing marks shown in Fig. 8 do not indicate TDC compression stroke for No. 1 cylinder, which is used during distributor installation. If distributor was removed, install timing chain and sprockets, aligning timing marks, Fig. 8, then rotate engine until No. 1 cylinder is on compression and camshaft timing mark is 180 degrees from valve timing position shown in Fig. 8. 8. Align dowel in camshaft with dowel hole in sprocket and install sprocket on camshaft. Do not attempt to drive sprocket on camshaft, as welch plug at rear of engine can be dislodged. 9. Draw sprocket onto camshaft, using the three mounting bolts. Tighten to specifications. 10. Lubricate timing chain and install cover. Page 3863 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2550 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1443 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Recall 95V139000: A/T Park Cable Lock Defect Parking Lock Cable: All Technical Service Bulletins Recall 95V139000: A/T Park Cable Lock Defect THE TRANSMISSION SHIFT-CABLE LOCK CLIP CAN BACK OUT OF ITS INSTALLED POSITION RESULTING IN A LOSS OF CABLE ADJUSTMENT. WHEN THE SHIFT LEVER IS PLACED IN THE "PARK" POSITION, THE "PARK" INDICATOR LIGHT MAY NOT ILLUMINATE. THE VEHICLE CAN MOVE UNINTENTIONALLY IF THE DRIVER DOES NOT NOTICE THAT THE INDICATOR LIGHT IS NOT ON AND DOES NOT APPLY THE PARKING BRAKE. DEALERS WILL ADJUST THE SHIFT CABLE AND INSTALL A LOCK CLIP. SYSTEM: POWERTRAIN; AUTOMATIC TRANSMISSION. VEHICLE DESCRIPTION: LIGHT DUTY TRUCKS EQUIPPED WITH M30/MT1 AUTOMATIC TRANSMISSIONS. NOTE: OWNERS WHO TAKE THEIR VEHICLES TO AN AUTHORIZED DEALER ON AN AGREED UPON SERVICE DATE AND DO NOT RECEIVE THE FREE REMEDY WITHIN A REASONABLE TIME, SHOULD CONTACT CHEVROLET AT 1-800-222-1020 OR GMC AT 1-800-462-8782. ALSO CONTACT THE NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION'S AUTO SAFETY HOTLINE AT 1-800-424-9393. 1995 CHEVROLET TRUCK C3500HD 1995 CHEVROLET TRUCK SUBURBAN 1995 CHEVROLET TRUCK TAHOE 1995 GMC C3500HD 1995 GMC SIERRA 1995 GMC SUBURBAN 1995 GMC YUKON Page 1006 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 323 5-Speed Manual Transmission W/4WD Page 1559 Page 3360 Throttle Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 80 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3232 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Capacity Specifications Fluid - Differential: Capacity Specifications Transmission/Transaxle Fill to the level of the filler plug hole. K2 models ............................................................................................................................................ ...................................................... 1.66L (1.75 Qt.) K3 models ............................................................................................................................................ ...................................................... 2.13L (2.25 Qt.) Fluid Capacity Rear Axle Oil, Pts. ............................................................................................................................... ............................................................................ [06] Front Axle Oil, Pts. ............................................................................................................................... ........................................................................... [07] [06] Chevrolet 8 1/2 inch, 4.2 pts.; Chevrolet 9 1/2 inch & Dana 9 3/4 & 10 1/2 inch, 5.5 pts.; Chevrolet 10 1/2 inch, 7.2 pts.; Dana 11 inch, 8.2 pts.; Rockwell 12 inch, 14 pts. [07] K 3500, 5.5 pts. Page 1320 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3950 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 1098 Fig.2-Symbols (Part 2 Of 3) Page 1225 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3890 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 2945 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 3279 Vehicle Speed Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3294 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2999 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3620 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3899 IMPORTANT: No physical adjustment of the IAC valve assembly is required after installation. The IAC valve pintle is reset by the control module system which causes the valve pintle to seat in the throttle body. The control module then has a reset procedure to set the correct pintle position. Proper idle regulation should result. INSTALL OR CONNECT 1. IAC valve into throttle body as follows: ^ Thread-mounted valve - Install with new gasket. ^ Flange-mounted valve - Install with new lubricated 0-ring, using attaching screw assemblies. Tighten Thread-mounted IAC valve assembly to 18.0 Nm (13.0 lb. ft.) with 32 mm (1-1/4") wrench. Tighten Flange-mounted attaching screw assemblies to 3.2 Nm (28.0 lb. in.). 2. Electrical connector to IAC valve. 3. Reset IAC valve pintle position: ^ Remove battery cable for 10 seconds. ^ Ignition "ON," engine "OFF" for 5 seconds. ^ Ignition "OFF," for 10 seconds. Page 3629 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1084 HD 5-Speed Manual Transmission W/4WD Page 1959 After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that we have done out best to remedy this condition without charge and within a reasonable time, you may wish to write to the Administrator, National Highway Traffic Safety Administration, 400 Seventh Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use 202-366-0123). We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your continued satisfaction with our products. Page 3851 Pinout Description: C2 (Part 1 Of 2) Pinout Description: C2 (Part 2 Of 2) Page 896 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 417 Coolant Temperature Sensor/Switch (For Computer): Description and Operation Engine Coolant Temperature (ECT) Sensor PURPOSE The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40° C (-40° F) while high temperature causes low resistance (70 ohms at 130° C (266° F). OPERATION The control module supplies a 5 volt signal to the ECT sensor through a resistor in the control module and measures the voltage. The voltage will be high when the engine is cold, and low when the engine is hot. Engine coolant temperature affects most systems controlled by the control module. Page 2946 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3420 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3893 Idle Air Control Valve: Connector Views Blower Motor Control Module, Idle Air Control Valve Idle Air Control Valve, Dist.ignition Control Module Page 2541 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3154 1994 P TRUCK 3A-66 Page 2553 Cooling Fan Page 1219 Fig.2-Symbols (Part 2 Of 3) Page 1968 1. The tire must be in the relaxed position when the repair unit is installed (Do not spread the beads excessively). Two-Piece Plug and Repair Units 1. If applicable, install the repair unit so that the alignment is correct. 2. Center the repair unit over the injury and stitch down thoroughly with the stitching tool, working from the center out. 3. Being careful not to stretch the plug material, cut the plug flush with the outer tread. Combination Repair/Plug Units 1. Pull the plug through the injury until the repair just reaches the liner. Stitch down thoroughly. 2. Follow the repair material manufacturer's recommendations for further installation instructions. 2. Consult your repair material supplier for the proper stitching tool. Safety Cage Page 3708 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3116 Manifold Absolute Pressure (MAP) Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 836 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1396 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 2323 Bulletin No.: 56-43-02 For reference purposes, Figure 1 shows a layout of the front drive system. Proper Labor Operation Usage If the replacement of the front axle output shaft seal(s) becomes necessary and the vehicle and repair are subject to the applicable warranty, only the following Labor Operation should be used: F1440: Seals Front Differential Output Shaft - Replace Right F1441: Seals Front Differential Output Shaft - Replace Left F1447: Seals Front Differential Output Shaft - Replace Both Important: This labor operation includes the time needed for removal and replacement of the front drive axle (halfshaft). DO NOT submit an additional claim for Front Drive Halfshaft R & R. Proper Drive Axle (Halfshaft) Handling to Prevent Inboard and Outboard Boot Damage When performing the output shaft seal replacement procedure described in the service manual, precautions should be taken to prevent damage to the inboard and outboard drive axle (halfshaft) boots (seals). The boots (seals) are delicate and critical to the performance of the halfshaft. Take the following precautions when performing the procedure: Page 3498 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 1829 1 Gallon 12346144 55 Gallon 12346145 In Canada 1 Liter 10952622 4 Liter 10952623 200 Liter 10952624 The 1995 Automatic Transmission/Transaxle fluid change intervals are the following: (1994 and prior should use the schedules as written in the Owner's Manual.) If the vehicle is mainly driven under one or more of these conditions: In heavy city traffic where the outside temperature regularly reaches 90°F (32°C) or higher. In hilly or mountainous terrain. When doing frequent trailer towing. Uses such as found in taxi, police car or delivery service. Change the fluid and filter every 50,000 miles (63,000 km). If the vehicle is not used mainly under any of these conditions, the fluid and filter do not require periodic changing for vehicles under 8,600 GVWR. Vehicles over 8,600 GVWR change the fluid and filter every 50,000 miles (83,000 km) regardless of driving conditions. Page 858 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3260 HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 567 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Diagram Information and Instructions Camshaft Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 948 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 99 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Brakes - Low Speed (Below 5 MPH) ABS Activation Wheel Speed Sensor: All Technical Service Bulletins Brakes - Low Speed (Below 5 MPH) ABS Activation Bulletin No.: 02-05-25-006B Date: January 05, 2006 TECHNICAL Subject: Antilock Brake (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface) Models: 1999-2000 Cadillac Escalade 1995-1999 Chevrolet Silverado (Old Style) 1995-2000 Chevrolet Suburban, Tahoe (Old Style) 1995-2003 Chevrolet Astro Van, Blazer, S10 1995-1999 GMC Sierra (Old Style) 1995-2000 GMC Yukon, Yukon XL (Old Style) 1995-2001 GMC Envoy, Jimmy 1995-2003 GMC Safari Van, Sonoma 1995-2001 Oldsmobile Bravada Supercede: This bulletin is being revised to update the correction and warranty information. Please discard Corporate Bulletin Number 02-05-25-006A (Section 05 - Brakes). Condition Some customers may comment on ABS activation at low speeds, usually below 8 km/h (5 mph). Upon investigation, the technician will find no DTCs set. Cause The cause of this condition may be an increased air gap between the wheel speed sensor and the hub reluctor ring due to rust and debris built up on the sensor mounting surface. Correction Measure AC voltage and clean wheel speed sensor mounting surfaces. 1. Raise the vehicle on a hoist. 2. Disconnect both the front wheel speed sensor harness connectors. 3. Place a DVM across the terminals of each sensor connector. 4. Rotate the wheel with hand speed and measure the ACmV's. The reading should be at least 350 ACmV's. 5. If the reading is between 200 and 350 ACmV's, remove the wheel, caliper and rotor in order to gain access to the speed sensor. 6. Remove the wheel speed sensor and plug the hole to prevent debris from falling into the hub during service. 7. Clean the wheel speed sensor mounting surface using a wire brush, sand paper, emery cloth, ScotchBrite(TM) or other suitable material. Be sure to thoroughly clean the wheel speed sensor surface. There should be no rust or corrosion. 8. Check the sensor head to determine if it has been warped/distorted due to the corrosion build up or other causes. Check the mounting surface on the sensor head for flatness by placing it on the edge of a metal machinists scale or other suitable straight edge to measure the flatness. Check the sensor for flatness in multiple (minimum 3) positions/directions. If the sensor head is distorted, replace the sensor. 9. Apply (spray) two thin coats of the specified rust penetrating lubricant (corrosion inhibitor) to the complete sensor mounting surface on the bearing hub. Allow to dry for 3-5 minutes between coats. Use ONLY Rust Penetrating Lubricant, P/N 89022217 (Canadian P/N 89022218). 10. When the corrosion inhibitor is dry to the touch (about 10 minutes), apply a thin layer of bearing grease to the hub surface and sensor 0-ring prior to sensor installation. Use ONLY Wheel Bearing Lubricant, P/N 01051344 (Canadian P/N 993037). Page 797 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3767 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 940 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 2613 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Harness View Engine Page 1045 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 374 PARTS INFORMATION WARRANTY INFORMATION Page 3379 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 2826 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3531 Idle Speed: Specifications Controlled Idle Speed Transmission Gear Idle Speed IAC Counts [1] OPEN/CLOSED Loop [2] Manual N 750 +/- 25 5-30 CL Automatic D 675 +/- 25 5-30 CL [1] On manual transmission vehicles the SCAN tool will display RDL in Neutral. Add 2 counts for engines with less than 500 miles. Add 2 counts for every 1000 ft. above sea level. [2] Let engine idle until proper fuel control status is reached (OPEN/CLOSED loop). Component Locations Oxygen Sensor (O2S) Page 3045 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 995 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3009 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Base Idle Speed Idle Speed: Specifications Base Idle Speed Transmission Gear Engine Speed [1] OPEN/CLOSED Loop [2] Manual N 625 +/- 25 CL Automatic D 625 +/- 25 CL [1] If the engine has less than 500 miles or is checked at altitudes above 1500 feet, the idle rpm with a seated IAC valve should be lower than above values. [2] Let engine idle until proper fuel control status (OPEN/CLOSED loop) is reached. Page 768 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 975 1995 G VAN 3A-72 Page 796 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1136 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1012 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1989 After contacting your dealer and the Customer Assistance Center, if you are still not satisfied that we have done out best to remedy this condition without charge and within a reasonable time, you may wish to write to the Administrator, National Highway Traffic Safety Administration, 400 Seventh Street, S.W., Washington, D.C. 20590 or call 1-800-424-9393 (Washington D.C. residents use 202-366-0123). We are sorry to cause you this inconvenience; however, we have taken this action in the interest of your continued satisfaction with our products. Page 396 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3868 Idle Air Control Valve: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 547 Vehicle Speed Sensor/Transducer - Cruise Control: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3446 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1210 Throttle Position Sensor: Adjustments The Throttle Position (TP) Sensor is not adjustable. With the ignition "ON" and the engine stopped, the TPS voltage should be less than 0.85 volts. If more than 0.85 volts, the TPS must be replaced. Page 3489 Fig.2-Symbols (Part 2 Of 3) Page 1515 Electronic 4-Speed Automatic Overdrive Transmission Page 2616 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1408 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 523 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3892 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 2703 Coolant Temperature Sensor/Switch (For Computer): Locations Component View Engine Coolant Temperature (ECT) Sensor The Engine Coolant Temperature (ECT) Sensor is located on the intake manifold next to the thermostat housing. Page 1057 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 1463 Throttle Body Injection (Part 7 Of 7) Page 956 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1134 Fig.2-Symbols (Part 2 Of 3) Page 3160 Oxygen Sensor: Mechanical Specifications Oxygen Sensor .................................................................................................................................... ........................................................ 41 Nm (30 lb.ft.) Page 2791 Parts are currently available from GMSPO. Warranty Information Labor Operation Description Labor Time J0100 Manifold, Exhaust Use published labor RH - Replace operation time J0101 Manifold, Exhaust Use published labor operation LH - Replace time Trouble Code 92. Page 996 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 1085 5-Speed Manual Transmission W/4WD HD Electronic 4-Speed Automatic Overdrive Transmission Page 1785 PARTS INFORMATION WARRANTY INFORMATION Page 986 5-Speed Manual Transmission W/4WD HD Electronic 4-Speed Automatic Overdrive Transmission Diagram Information and Instructions Throttle Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 661 Fig.1-Symbols (Part 1 Of 3) Page 1596 Figure 1: Full Tread View - "NORMAL" Tire "Feathering" Wear on the Shoulder/Adjacent/Center Ribs Figure 2: Tire Shoulder View Example 1 - "NORMAL" Tire "Feathering" Wear on the Shoulder Figure 3: Tire Shoulder View Example 2 - "NORMAL" Tire "Feathering" Wear Figure 4: Detail Side View of Tire Shoulder Area - "NORMAL" Tire "Feathering" Wear Important When a wheel alignment is deemed necessary for tire wear, be sure to document on the repair order, in as much detail as possible, the severity and type of tire wear (e.g., severe center wear or severe inside or outside shoulder wear) and the position of the tire on the vehicle (RF, LF, LR, RR). Please note the customer's concern with the wear such as, noise, appearance, wear life, etc. A field product report with pictures of the tire wear condition is recommended. Refer to Corporate Bulletin Number 02-00-89-002J and #07-00-89-036C. 4. Other repairs that affect wheel alignment; e.g., certain component replacement such as suspension control arm replacement, engine cradle adjustment/replace, steering gear replacement, steering tie rod replace, suspension strut/shock, steering knuckle, etc. may require a wheel alignment. Important If other components or repairs are identified as affecting the wheel alignment, policy calls for the wheel alignment labor time to be charged to the replaced/repaired component's labor operation time rather than the wheel alignment labor operations. Important Vibration type customer concerns are generally NOT due to wheel alignment except in the rare cases; e.g., extreme diagonal wear across the tread. In general, wheel alignments are NOT to be performed as an investigation/correction for vibration concerns. "Normal Operation" Conditions Vehicle Lead/Pull Due to Road Crown or Slope: As part of "Normal Operation," vehicles will follow side-to-side or left to right road crown or slope. Be sure to verify from the customer the types of roads they are driving as they may not recognize the influence of road crown on vehicle lead/pull and steering wheel angle. If a vehicle requires significant steering effort to prevent it from "climbing" the road crown there may be an issue to be looked into further. Important Page 238 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 972 K Series - 4 Wheel Drive Cooling System, A/C - Aluminum Heater Cores/Radiators Heater Core: Technical Service Bulletins Cooling System, A/C - Aluminum Heater Cores/Radiators INFORMATION Bulletin No.: 05-06-02-001A Date: July 16, 2008 Subject: Information On Aluminum Heater Core and/or Radiator Replacement Models: 2005 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2003-2005 HUMMER H2 Supercede: This bulletin is being revised to update the Warranty Information. Please discard Corporate Bulletin Number 05-06-02-001 (Section 06 - Engine/Propulsion System). Important: 2004-05 Chevrolet Aveo (Pontiac Wave, Canada Only) does not use DEX-COOL(R). Refer to the flushing procedure explained later in this bulletin. The following information should be utilized when servicing aluminum heater core and/or radiators on repeat visits. A replacement may be necessary because erosion, corrosion, or insufficient inhibitor levels may cause damage to the heater core, radiator or water pump. A coolant check should be performed whenever a heater core, radiator, or water pump is replaced. The following procedures/ inspections should be done to verify proper coolant effectiveness. Caution: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if the radiator cap or surge tank cap is removed while the engine and radiator are still hot. Important: If the vehicle's coolant is low, drained out, or the customer has repeatedly added coolant or water to the system, then the system should be completely flushed using the procedure explained later in this bulletin. Technician Diagnosis ^ Verify coolant concentration. A 50% coolant/water solution ensures proper freeze and corrosion protection. Inhibitor levels cannot be easily measured in the field, but can be indirectly done by the measurement of coolant concentration. This must be done by using a Refractometer J 23688 (Fahrenheit scale) or J 26568 (centigrade scale), or equivalent, coolant tester. The Refractometer uses a minimal amount of coolant that can be taken from the coolant recovery reservoir, radiator or the engine block. Inexpensive gravity float testers (floating balls) will not completely analyze the coolant concentration fully and should not be used. The concentration levels should be between 50% and 65% coolant concentrate. This mixture will have a freeze point protection of -34 degrees Fahrenheit (-37 degrees Celsius). If the concentration is below 50%, the cooling system must be flushed. ^ Inspect the coolant flow restrictor if the vehicle is equipped with one. Refer to Service Information (SI) and/or the appropriate Service Manual for component location and condition for operation. ^ Verify that no electrolysis is present in the cooling system. This electrolysis test can be performed before or after the system has been repaired. Use a digital voltmeter set to 12 volts. Attach one test lead to the negative battery post and insert the other test lead into the radiator coolant, making sure the lead does not touch the filler neck or core. Any voltage reading over 0.3 volts indicates that stray current is finding its way into the coolant. Electrolysis is often an intermittent condition that occurs when a device or accessory that is mounted to the radiator is energized. This type of current could be caused from a poorly grounded cooling fan or some other accessory and can be verified by watching the volt meter and turning on and off various accessories or engage the starter motor. Before using one of the following flush procedures, the coolant recovery reservoir must be removed, drained, cleaned and reinstalled before refilling the system. Notice: ^ Using coolant other than DEX‐COOL(R) may cause premature engine, heater core or radiator corrosion. In addition, the engine coolant may require changing sooner, at 30,000 miles (50,000 km) or 24 months, whichever occurs first. Any repairs would not be covered by your warranty. Always use DEX‐COOL(R) (silicate free) coolant in your vehicle. ^ If you use an improper coolant mixture, your engine could overheat and be badly damaged. The repair cost would not be covered by your warranty. Too much water in the mixture can freeze and crack the engine, radiator, heater core and other parts. Page 603 Dimmer Switch: Technical Service Bulletins I/P Dimmer/Courtesy Lamp Rotary Switch - Operation File In Section: 8 - Chassis/Body Electrical Bulletin No.: 56-82-02 Date: April, 1995 Subject: Operation of the Instrument Cluster Dimmer and Interior/Dome Lamp Rotary Wheel Switch Models: 1995 Chevrolet and GMC Truck C/K Models The instrument panel dimmer wheel now has two detent positions. The first detent position puts the radio display and PRNDL light emitting diode on maximum intensity, along with the instrument cluster illumination. This is often called the "Parade Mode". The second detent will turn on the interior/dome light. The switch directly below the park/headlamp switch, labeled dome lamp, will not illuminate the dome lamp. Its purpose is to prevent the dome lamp from coming on when the doors are open. In addition, it does not interfere with operation of the rotary dimmer switch described above. Page 3173 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2931 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Service and Repair Fuel Pressure Release: Service and Repair PROCEDURE: NOTE: A constant bleed feature in the pressure regulator relieves pressure when engine is turned "OFF." - Disconnect negative battery terminal to avoid possible fuel discharge if an accidental attempt is made to start the engine. - Loosen fuel filler cap to relieve tank vapor pressure. - The internal constant bleed feature of the TBI relieves fuel pump system pressure when the engine is turned "OFF." Therefore, NO further pressure relief procedure is required. Page 2895 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2726 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 172 PCM Connector Pin-Out Page 3886 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2094 service operation. A simple distraction or time constraint that rushes the job may result in personal injury if the greatest of care is not exercised. Make it a habit to double check your work and to always side with caution when installing wheels. Disclaimer Page 410 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3007 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 2833 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Specifications Spark Plug: Specifications Spark Plug Gap ................................................................................................................................... ............................................. 0.90 mm (0.035 inches) Spark Plug Torque ............................................................................................................................... ...................................................... 15 Nm (11 lb. ft.) Spark Plug Type .................................................................................................................................. .............................................................. AC CR43TS NOTE: Check the gap specifications found on the Emissions Control Label. If the gap is different from what is listed here, use the information on the label. Front Heater Core: Service and Repair Front HEATER CORE REPLACEMENT Heater Case (1 OF 2) Heater Case (2 OF 2) Remove or Disconnect 1. Engine coolant. 2. Instrument panel storage compartment. See: Body and Frame/Interior Moulding / Trim/Dash Board / Instrument Panel/Service and Repair 3. Electrical connectors, as necessary. 4. Center floor air distribution duct. 5. Hinge pillar trim panels. 6. Blower motor cover. 7. Blower motor. 8. Steering column. 9. Roll instrument panel back. 10. Coolant recovery reservoir. 11. Heater hoses. Refer to "Heater Hoses" in this section. 12. Screw on interior side of cowl, near the evaporator pipe (if equipped) while holding heater case to the cowl. 13. Four screws on the engine side of the cowl holding the heater case to the cowl. 14. Two nuts on the engine side of the cowl holding the heater case to the cowl. 15. Heater case. - It may be necessary to have an assistant when removing heater case. 16. Heater cover. - Remove seven screws that hold cover to the heater case. 17. Heater core from retainer. Page 470 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3662 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3299 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1735 1993 to 1995 L05 VIN K Install the appropriate check valve oil filter P/N 25160561 (PF1218 for two-wheel C-series and P/N 12555891 (FRAM PH3980) for four-wheel drive K-series). If the oil filter does not cure the condition, install the appropriate calibration from the table (calibrations are available for some 1993 and 1994 L05 applications). All calibrations are for light duty vehicles equipped with 4L60-E (M30) transmissions (no heavy duty emission/4L80-E calibrations are available). If a calibration is not offered or does not cure the short duration cold knock condition, install the appropriate main bearings as determined by the procedure. 1990-94 L19 VIN N Page 2484 Spark Plug Diagnosis Page 3411 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3333 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1158 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 1609 Alignment: Service and Repair Camber & Caster Adjustment Kit Installation Fig. 3 Upper Control Arm Removal Fig. 4 Alignment Service Kit 15538596 Installation As originally installed, the upper control arm cannot be adjusted for camber or caster. However, if the camber or caster is measured and found to be out of specification, the camber and caster can be set to proper specifications using adjustment kit 15538596, or equivalent. To install, proceed as follows: 1. Raise and support vehicle and lower control arms, then remove nut (60), washer (61) and bolt (62) from upper control arm bracket (44). Discard nut, washer and bolt. 2. Remove large washers (40), Figs. 3 and 4, which are welded to the upper control arm frame brackets. 3. Remove weld beads from the upper control arm bracket. Grind area smooth. 4. Install adjusting cams (49) to bracket (44). 5. Install bolt (48) and nut (50). 6. Adjust camber and caster to specifications by rotating bolt head. Tighten nuts to specification. See Steering and Suspension/Tires, Wheels and Alignment/Specifications/Mechanical. Page 3011 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 1371 A. On G, J and N Models: DO NOT REMOVE THE STEERING COLUMN as indicated in the Service Manual procedure. 1. Remove the tilt lever, upper and lower column covers. 2. Drill hole in module housing as indicated in the illustration using a short drill bit (1/8" followed by 9/32") and 90 degree drill motor or go degree drill attachment to break or access the retaining spring for the lock cylinder button, see Figure 2. 3. Using a pick or needle nose pliers, remove the retaining spring from the hole. 4. Using pliers, grasp and remove the retaining button for the cylinder. 5. Remove the cylinder from the housing. 6. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 7. Install the new cylinder and reinstall the steering column components. B. On U, W, and light duty trucks, follow the Service Manual procedure for keys missing, or cylinders won't rotate. Procedure: Instrument Panel Mounted Switches Important: This new procedure involves drilling a hole through the plastic ignition switch and into the lock cylinder slightly to break or access a cylinder release button retaining spring (similar to G, J and N models). The removal of the broken spring and then the release button will allow the switch to be reused. 1. Remove the necessary trim panels to gain access to the instrument panel mounted switch (refer to information in "Body and Accessories Section, Instrument Panel, Gauges and Consoles"). a. On instrument panel mounted N models (Malibu and Cutlass), the switch and cylinder can be accessed after removing the instrument cluster assembly and positioning the switch/cylinder upward in the cavity for the cluster assembly. b. On Corvette models, the switch and cylinder can be accessed after removing the knee bolster from the lower instrument panel area and positioning the switch/cylinder downward from its location on the instrument panel. 2. Loosen switch from instrument panel and disconnect the electrical connections, BUT NOT the cable connection for BTSI (Brake/Transmission Shift Interlock). 3. Protect the immediate work area with a fender cover or other suitable material. Page 3238 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Locations Brake Light Switch: Locations Instrument Panel Wiring, LH Side Page 1516 Transmission Position Switch/Sensor: Locations Park/Neutral Position and Backup Lamp Switch, With 4WD HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 279 Cargo Lamp Switch Wiring Page 3435 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 835 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 1491 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 81 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3665 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Locations Front Door Wiring Page 1739 Warranty Information Page 1338 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Harness View Engine Page 3617 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1102 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3647 1994 Models: 1995 Models: Page 3129 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1092 HD 5-Speed Manual Transmission W/4WD Page 3864 Fig.1-Symbols (Part 1 Of 3) Page 3132 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Diagram Information and Instructions Air Flow Meter/Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Service and Repair Malfunction Indicator Lamp: Service and Repair The CHECK ENGINE LAMP will be illuminated when the ignition switch is placed in the "ON" position. When the engine is started, the lamp should turn "OFF". If the lamp remains "ON" for 10 seconds or constantly after the engine is started, the self diagnosis system has detected a problem and has stored a code in the system Control Module. After diagnosis and repair, the ECM memory can be cleared of codes by removing the Control Module fuse or disconnecting the battery ground cable for approximately 30 seconds, with ignition switch in the "OFF" position. NOTE If battery ground cable is disconnected to clear codes, components such as clocks, electronically tuned radios etc., will have to be reset. - It is a good idea to record preset radio stations before disconnecting the negative battery cable. This will allow the stations to be reset as to not inconvenience the customer. Page 3216 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3198 Oxygen Sensor: Description and Operation Oxygen Sensor PURPOSE: The Oxygen Sensor (O2S) is essentially a small variable battery; it has the ability to produce a low voltage signal that feeds information on engine exhaust oxygen content to the control module. CONSTRUCTION: The O2 Sensor is constructed from a zirconia/platinum electrolytic element. Zirconia is an electrolyte that conducts electricity under certain chemical conditions. The element is made of a ceramic material and is an insulator when cold. At operating temperature, 315°C (600°F), the element becomes a semiconductor. A platinum coating on the outer surface of the element stimulates further combustion of the exhaust gases right at the surface and this helps keep the element up to the desired temperature. Due to the electrolytic properties of the element the oxygen concentration differences between the reference air and the exhaust gases produce small voltages. OPERATION: A rich exhaust (excessive fuel) has almost no oxygen. When there is a large difference in the amount of oxygen touching the inside and outside surfaces, there is more conduction, and the sensor puts out a voltage signal above 0.6 volt (600 mV). With lean exhaust (excessive oxygen) there is about two percent oxygen in the exhaust. This is a smaller difference in oxygen from the outside surfaces which results in less conduction and a voltage signal below 0.3 volt (300 mV). The voltages are monitored and used by the control module to "fine tune" the air/fuel ratio to achieve the ideal mixture desired. The control module puts out a reference signal of 0.45 volt (450 mV). The reference signal serves two purposes. The first is to run the engine when it is in "Open Loop" mode of operation. When the air/fuel ratio is correct the control module "senses" 450 mV. When the engine is operating with a rich air/fuel ratio there is a reduction of free oxygen in the exhaust stream and the oxygen sensor voltage rises above the reference voltage. When the engine is running lean the voltage drops below the reference voltage due to excess oxygen in the exhaust stream. The oxygen sensor provides the feedback information for the "Closed Loop" operating mode of the fuel delivery system. The oxygen sensor indicates to the control module what is happening in the exhaust. It does not cause things to happen. It is a type of gauge: Low voltage output = lean mixture = high oxygen content in exhaust; high voltage output = rich mixture = low oxygen content in the exhaust. CONDITIONS THAT CAN SET CODES: An open oxygen sensor, should set a DTC 13. A constant low voltage in the oxygen sensor circuit should set a DTC 44. A constant high voltage in the circuit should set a DTC 45. DTC 44 and DTC 45 could also be set as a result of fuel system problems. Refer to "DTC Charts" for conditions that can cause a lean or rich system. Page 1736 Install a check valve oil filter; no other recommended actions at this time. Important: The previous actions are only applicable to short duration cold knock. These actions will not eliminate a knock occurring under load or a knock lasting for more than 10 seconds. Two main bearing procedures are recommended: 1. For main bearing replacement with the engine IN the vehicle: C, G, P, M and L vehicles 2. For main bearing replacement with the engine OUT OF the vehicle: K, S and T THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE IN THE VEHICLE Recommended for C, G, P, M and L vehicles. Important: A OEM training video has been produced for in-vehicle main bearing replacement procedure. One copy of the video will be sent to each dealer. If the video has not been received, contact XPRESS 1 Distribution Center at 1-800-783-3034. Main Bearing Clearance Determination and Installation Procedure 1. REMOVE THE SERPENTINE BELT, dipstick, dipstick tube and disconnect the negative battery cable. 2. Raise the vehicle and remove (or set aside) any parts restricting access to the oil pan bolts (i.e., starter motor, oil cooler lines, oil filter adapter, flywheel inspection cover). 3. Remove the oil pan, oil pump, and shield. 4. Remove # 5 (flange) bearing cap. Wipe the oil from the crankshaft journal and the lower main bearing insert. 5. Place a screw jack under an accessible part of the crankshaft, carefully apply pressure to the crankshaft to force it solidly against the top bearing insert. The reason for this is to remove any clearance between the top bearing insert and the crankshaft. If this step is not performed, a smaller than actual clearance will be measured. Important: This should be done as close as possible to the bearing being measured. This step is only required for on-vehicle service where the engine cannot be turned upside down as on an engine stand. 6. Place a piece of plastigage across the width of the lower bearing insert (parallel to the centerline of the crankshaft). 7. Reinstall # 5 main bearing cap. Torque to 110 N.m (80 lb ft). Do not allow crankshaft to turn. 8. Carefully remove the # 5 main bearing cap and bearing insert. The flattened plastigage will adhere to either the bearing insert or the crank journal. Do not remove the plastigage from the insert or journal. 9. On the edge of the plastigage envelope, there is a graduated scale. Without removing the flattened plastigage, measure its width at the widest point using the graduated scale on the plastigage envelope. 10. The desired main bearing clearance is 0.0008" - 0.0028". If the clearance measured with the plastigage is greater than 0.0028", write down the clearance. Next, read the back of the bearing insert to determine what size bearing was originally installed (usual STD, 0.0006", 0.0010" or 0.0012"). The size stamped on the bearing is the effective undersize when both inserts are installed. For example, a 0.0006" undersize bearing set consists of two (2) 0.0003" thicker bearing inserts, both stamped 0.0006". 11. Remove the top bearing insert using tool J 8080 and read the back to determine what size upper bearing insert was originally installed. The top insert may be different size than the bottom. 12. Calculate the original bearing undersize by dividing the size on each insert by 2, then add the values together. EXAMPLE 1: The lower insert is stamped 0.0006" and the upper is stamped 0.0010". Divide 0.0006" by two to get 0.0003". Divide 0.0010" by 2 to get 0.0005". Add 0.0003" and 0.0005" together to calculate the bearing undersize, which is 0.0008" in this case. Locations Clutch Switch: Locations Cruise Control Wiring At top of clutch pedal. Page 2612 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1239 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Locations Safety Belt Switch Wiring Page 827 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 2936 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 2683 For vehicles repaired under warranty, use the table. Disclaimer Page 2247 Drive Belt: Service and Repair DRIVE BELT REPLACEMENT REMOVE CAUTION: Do not rotate the tensioner except as noted above. Also, do not allow the tensioner to snap into the "free" position. Either of these conditions could damage the belt and/or tensioner. 1. Use a 1/2 inch breaker bar with a socket placed on the pulley axis bolt to rotate the tensioner clockwise and release tension. 2. Belt. INSTALL 1. Route belt over all of the pulleys except the belt tensioner. 2. Use a 1/2 inch breaker bar with socket placed on the tensioner pulley axis bolt and rotate the tensioner to the released position. 3. Belt over tensioner pulley. Slowly allow tensioner to move back into installed position. 4. Check the belt for correct "V" groove tracking into each pulley. Page 897 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 2685 Radiator: Service and Repair 1. Drain coolant from radiator. 2. Remove upper fan shroud bolts and upper fan shroud. 3. Remove upper insulators and brackets. 4. Remove upper and lower radiator hoses. 5. Disconnect transmission fluid cooler lines. 6. Disconnect engine oil cooler lines. 7. Remove lower fan shroud retaining bolts and lower fan shroud. 8. Disconnect overflow hose. 9. Remove radiator from lower insulators and brackets. 10. Reverse procedure to install, noting the following: a. Torque fan shroud attaching bolts to 6 ft. lbs. b. Torque engine oil cooler line fittings to 18 ft. lbs. c. Torque transmission fluid cooler lines to 19 ft. lbs. Diagram Information and Instructions Coolant Temperature Sensor/Switch (For Computer): Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 765 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3213 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 93 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 363 PARTS INFORMATION WARRANTY INFORMATION Page 3259 HD Electronic 4-Speed Automatic Overdrive Transmission With 4WD Page 1520 Transmission Range Switch (C2) Page 1890 Fig. 8 Plastic Reservoir Bleeder Adapter Installation Page 3101 Knock Sensor Circuit CIRCUIT DESCRIPTION The Knock Sensor (KS) system consist of a knock sensor with one wire that goes directly to the PCM. There is a check performed by the PCM. The check consist of monitoring CKT 496 for a voltage that is more than 0.04 volt and less than 4.6 volts. If the voltage is either too high or too low for 16 or more seconds, DTC 43 will set. CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic chart. 1. The first test is to determine if the system is functioning at the present time. 2. Test two determines the state of the 5 volt reference voltage applied to the knock sensor circuit. DIAGNOSTIC AIDS The PCM applies 5 volts to CKT 496. A 3900 ohm resistor in the knock sensor reduces the voltage to about 2.5 volts. When knock occurs, the knock sensor produces a small AC voltage that rides on top of the 2.5 volts already applied. An AC voltage monitor, in the PCM, is able to read this signal as knock and incrementally retard spark. If the KS system checks OK, but detonation is the complaint, refer to Diagnosis By Symptom / Detonation, Spark Knock See: Computers and Control Systems/Testing and Inspection/Symptom Related Diagnostic Procedures/Detonation/ Spark Knock Page 3111 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Locations Cargo Lamp Switch Wiring Page 298 Page 3682 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 779 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 2956 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 3021 Temp Sensor Circuit Wiring Page 2301 Lower Control Arm Replacement Procedure (K-Trucks with 8600 # GVW's and Below) Following the procedure given in section 3C of the service manual, replace the lower control arms with the new style lower control arms. It should be noted that the new lower control arms include a pressed in ball joint. Part numbers for the lower control arm front and rear bushings are also given below. Front Axle Seal Cover Installation Procedure Follow the instructions included in the seal cover service kits. Appropriate part numbers are shown below. Be sure to order the correct seal cover based on the GVW of the subject vehicle. Parts Information Parts are currently available from GMSPO. Warranty Information Important: Implementation of this bulletin by Canadian dealers requires prior DSM approval. Installation of seal cover service kits is an 'owner pay' service and as such requires prior owner approval. For vehicles repaired under warranty. Page 3491 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1009 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2056 10. Align the inscribed mark on the tire with the valve stem on the wheel. 11. Reinstall the Tire Pressure Sensor. Refer to Tire Pressure Sensor installation procedure in SI. 12. Mount the tire on the wheel. Refer to Tire Mounting and Dismounting. 13. Pressurize the tire to 276 kPa (40 psi) and inspect for leaks. 14. Adjust tire pressure to meet the placard specification. 15. Balance the tire/wheel assembly. Refer to Tire and Wheel Assembly Balancing - Off-Vehicle. 16. Install the tire and wheel assembly onto the vehicle. Refer to the appropriate service procedure in SI. Parts Information Warranty Information (excluding Saab U.S. Models) Important The Silicone - Adhesive/Sealant comes in a case quantity of six. ONLY charge warranty one tube of adhesive/sealant per wheel repair. For vehicles repaired under warranty, use: One leak repair per wheel. Warranty Information (Saab U.S. Models) For vehicles repaired under warranty, use the table above. Disclaimer Page 3029 Fig.1-Symbols (Part 1 Of 3) Page 1313 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 754 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 186 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3808 PCM Connector Pin-Out Page 2546 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1334 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 521 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Initial Inspection and Diagnostic Overview Radiator Cooling Fan Motor: Initial Inspection and Diagnostic Overview Check condition of IGN E Fuse and AUX FAN Fuse. If either fuse is open, then LOCATE and REPAIR source of overload. Replace fuse(s). Check that grounds G112 and G113 are clean and tight. Check that the Auxiliary Cooling Fan Relay is securely mounted in its socket. Check for a broken (or partially broken) wire inside of the insulation which could cause system malfunction but prove "GOOD" in continuity/voltage check with a system disconnected. These circuits may be intermittent or resistive when loaded, and if possible, should be checked by monitoring for a voltage drop with the system operational (under load). Check for proper installation of aftermarket electronic equipment which may affect the integrity of other systems (Refer "Troubleshooting Procedures,"). See: Diagrams/Diagnostic Aids Page 2468 Spark Plug Wire: Service and Repair SERVICE CAUTIONS 1. Twist boots one-half turn before removing. 2. When removing the boot, do not use pliers or other tools that could tear the boot. 3. Do not force anything between the wire and the boot, or through the silicone jacket of the wiring. 4. Do not pull on the wires to remove the boot. Pull on the boot or use a tool designed for this purpose. 5. Special care should be used when installing spark plug boots to ensure the metal terminal within the boot is fully seated on the spark plug terminal and the boot has not moved on the wire. SPARK PLUG WIRE REPLACEMENT Spark plug wire routings must be kept intact during service and followed exactly when spark plug wires have been disconnected or when replacement of the spark plug wires is necessary. Failure to route the spark plug wires properly can lead to radio noise and crossfiring of the spark Page 2481 Spark Plug: Service Precautions WARNING: If you smoke while handling coated spark plugs, wear gloves to prevent transfer of coating to cigarette and subsequent burning of coating. Always wash hands after handling coated plugs. CAUTION: Observe service precautions: - Allow engine to cool BEFORE removing spark plugs. Attempting to remove spark plugs from a hot engine may cause plug to seize, causing damage to cylinder head threads. - Clean spark plug recess area BEFORE removing plug. Failure to do so can result in engine damage due to dirt or foreign material entering cylinder head, or in contamination of cylinder head threads. Contaminated threads may prevent proper seating of new plug. - Use only spark plugs specified for use in the vehicle. DO NOT install spark plugs that are either "hotter" or "colder" than those specified for the vehicle. Installing plugs of another type can severely damage the engine. Page 2725 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1483 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3715 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3702 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3215 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Locations Heater Control Valve: Locations This vehicle does not use a Heater Control Valve (Coolant Valve) and the OEM service manual does not provide any information for this component. Refer to Heater Hose / Locations. Page 963 MAP Sensor Circuit Page 359 12. Using template (Figure 4), mark cutting lines on the upper evaporator case using a china marker or equivalent. Do not remove the locating tabs from the templates, they are needed to position the cut area for the access doors (Figure 1). Component Locations Data Link Connector: Component Locations The Data Link Connector is located under the left side of the instrument panel. Page 2324 Remove the drive axle (halfshaft) completely from the vehicle to gain access to the output shaft. DO NOT try to remove the output shaft without first removing the drive axle (halfshaft) from the vehicle. Damage to halfshaft boots (seals) may result. Furthermore, attempts to reinstall the output shaft into the differential with the halfshaft pushed off to one side may result In damage to the output shaft seal. ^ Avoid contact between the inboard and outboard halfshaft boots (seals) and any surface which could cause a cut, nick, or abrasion. ^ When loosening or tightening the 6 bolts which secure the halfshaft to the output shaft, care should be taken to prevent tools from contacting the inboard halfshaft boot (seal). Page 3627 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Specifications Camshaft: Specifications Engine Liter/CID .................................................................................................................................. ............................................................. 7.4L/V8-454 All specifications given in inches. Camshaft Journal Diameter ................................................................................................................. ............................................................ 1.9482-1.9492 Camshaft Bearing Clearance ......................... .................................................................................................................................................. 0.0015-0.0035 Camshaft Runout (Max.) ............................................................................................. ................................................................................................ 0.0015 Lifter Bore Diameter ............... .............................................................................................................................................................. .......... 0.8432-0.8442 Lifter Diameter .................................................................................................. ............................................................................................. 0.8420-0.8427 Lifter To Bore Clearance .............................................................................................................................................................. .................. 0.0008-0.0025 Lobe lift ± 0.002 in. Intake ................................................................................................................................................... .............................................................. 0.2487 in. Exhaust ................................................................ ............................................................................................................................................... 0.2537 in. Specifications Compression Check: Specifications Minimum, 698 kPa (100 psi) @ 200 rpm. The lowest cylinder reading should not be less than 80% of the highest. Perform compression test with engine at normal operating temperature, spark plugs removed and throttle wide open. Page 814 Fig.1-Symbols (Part 1 Of 3) Page 2979 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2352 Oil Pressure Switch (For Fuel Pump): Description and Operation PURPOSE: As a back-up system to the fuel pump relay, the fuel pump is also turned ON by the oil pressure switch. OPERATION: When the engine oil pressure reaches about 28 kPa (4 psi), through cranking the oil pressure switch will close to complete the circuit to the fuel pump. Page 3380 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Locations ABS Main Relay: Locations The relay is located inside the Brake Pressure Modulator Valve (BPMV) and cannot be serviced. Harness View Engine Page 76 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Diagram Information and Instructions Coolant Temperature Sensor/Switch (For Computer): Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3200 Oxygen Sensor: Service and Repair Oxygen Sensor NOTE: - The Oxygen Sensor (O2S) has a permanently attached pig-tail and connector. This pig-tail should not be removed, since removal will affect proper operation of the O2S. - Take care when handling the O2S. The in-line electrical connector and louvered end must be kept free of grease, dirt, or other contaminants. Also, avoid using cleaning solvents of any type. Do not drop or roughly handle the O2S. REMOVE OR DISCONNECT: ^ The O2S may be difficult to remove when engine temperature is below 48°C (120°F). Use caution, since excessive force may damage threads in exhaust manifold or pipe. - Disconnect negative battery cable. - Disconnect electrical connector releasing locking tab. - Using suitable wrench, carefully back out sensor. INSTALL OR CONNECT: IMPORTANT: ^ A special anti-seize compound is used on the 02S threads. The compound consists of liquid graphite and glass beads. The graphite will tend to burn away, but the glass beads will remain, making the sensor easier to remove. ^ New, or service replacement sensors will already have the compound applied to the threads. If a sensor is removed from an engine, and if for any reason it is to be reinstalled, the threads must have anti-seize compound applied before reinstallation. - Coat threads of 02S with anti-seize compound (GM P/N 5613695 or equivalent), if necessary. - Install and torque oxygen sensor to 41 Nm (30 lb.ft.). - Reconnect electrical connector. - Reconnect negative battery cable. Page 2597 Fig.2-Symbols (Part 2 Of 3) Valve Specifications Valve: Specifications Valve Specifications Engine Liter/CID .................................................................................................................................. ........................................................... 7.4L/V8-454 All specifications given in inches. Stem Diameter Std. Intake ................................................................................................................................................... ...................................................... 0.3715-0.3722 Exhaust ................................................................ ...................................................................................................................................... 0.3715-0.3722 Maximum Tip Refinish ......................................................................................................................... ........................................................................ [03] Face Angle .......................................................... ....................................................................................................................................................... 45 deg. Margin [01] Intake ................................................................................................................................................... .................................................................. 0.0315 Exhaust ................................................................. .................................................................................................................................................. 0.0315 Valve Lash ........................................................................................................................................... ........................................................................... [06] [01] Minimum. [03] Grind only enough to provide true surface. After grinding valve stems, ensure sufficient clearance remains between rocker arm & valve spring cap or rotator. [06] Torque rocker arm bolt to 40 ft. lbs Page 1419 Neutral Safety Switch: Connector Views Transmission Range Switch (C1) Transmission Range Switch (C2) Page 1569 5-Speed Manual Transmission W/4WD Page 313 Service and Repair Crankshaft Main Bearing Seal: Service and Repair REMOVAL 1. Remove transmission, then the clutch and flywheel or flexplate, as equipped. 2. Carefully remove seal as not to nick the crankshaft sealing surface. 3. Inspect chamfer on crankshaft for grit, loose rust and burrs. Correct as necessary. INSTALLATION 1. Using rear crankshaft seal installer tool No. J-38841 or equivalent, install crankshaft rear oil seal as follows: a. Using clean engine oil, lubricate inner and outer diameter of seal. b. Install new seal onto tool. c. Thread attaching screws into the tapped holes in the crankshaft. d. Using a screwdriver, tighten attaching screws. This will ensure that the seal is installed properly over crankshaft assembly. e. Turn tool handle until it bottoms out. f. Remove tool. Page 1462 Brake Switch - TCC: Electrical Diagrams Antilock Brakes (Part 1 Of 2) Page 680 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3331 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 913 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1828 Fluid - A/T: Technical Service Bulletins A/T - DEXRON III Fluid Introduction File In Section: 0 - General Information Bulletin No.: 57-02-01 Date: March, 1995 SERVICE MANUAL UPDATE Subject: Section 0 - General Information - DEXRON(R)-III Transmission Fluid Introduction Models: 1995 and Prior Passenger Cars and Trucks General Motors has phased in a new automatic transmission fluid, DEXRON(R)-III, that does not need replacing under normal service. DEXRON(R)-III is designed to help the transmission deliver the best possible performance under all conditions. Refer to Figure 1. The improvements in DEXRON(R)-III include better friction stability, more high temperature oxidation stability and better material compatibility. DEXRON(R)-III has the same low temperature fluidity as DEXRON(R)-IIE, for better transmission performance in cold weather. DEXRON(R)-IIE and DEXRON(R)-III are fully compatible. DEXRON(R)-III is fully compatible with any General Motors passenger vehicle or light truck with automatic transmission and built since 1949. Dealers should require their supplier to include the DEXRON(R)-III license number on all automatic transmission fluid invoices. Starting February 1, 1994 DEXRON(R)-III was phased into all North American assembly plants. DEXRON(R)-III fluid is available from GMSPO (see fluid numbers below): U.S. 1 Quart 12346143 A/C Compressor - Loud Knocking Noise Refrigerant Filter: All Technical Service Bulletins A/C Compressor - Loud Knocking Noise File in Section: 1 - HVAC Bulletin No.: 56-12-01 Date: February, 1995 SUBJECT: Loud Knock from A/C Compressor (Replace Compressor and Thermal Expansion Valve) MODELS: 1994-95 Chevrolet C/K Models built before VIN breakpoint SJ300349 1994-95 GMC Truck C/K Models built before VIN breakpoint SJ701253 with Rear A/C (RPO C69) or Rear Heater and A/C (RPOs C36, C69) CONDITION Some owner's of the above listed vehicles may comment that the A/C compressor has developed a loud knocking noise. The A/C system will continue to cool. CAUSE When the rear A/C system is shut off, a refrigerant flood back condition may occur through the rear A/C system. This flooding degreases the internal parts of the compressor resulting in rapid slider block wear and the resulting loud knocking noise. A poor contact between the TXV capillary tube and the rear evaporator outlet tube can allow the TXV to remain open when the rear system is not in use. The open TXV may allow liquid refrigerant to flood back through the rear system (liquid line, TXV, evaporator, rear suction line) and subsequently flood the compressor. CORRECTION Replace the A/C compressor, the thermal expansion valve (TXV), and add an in-line filter. Service Procedure 1. Recover the R-134a refrigerant charge (Section 1-B of Service Manual). 2. Replace the compressor and balance the PAG lubricant in the system following the procedures in the vehicle service manual. 3. Install an in-line filter in the liquid line after the condenser and before the "Y" in the line separating the front and rear systems. 4. Remove, inspect and clean the orifice tube for the front system. It is located in the liquid line after the "Y" joint. 5. Replace the orifice tube. 6. Disconnect seat belt and remove rear bench seat. 7. Remove the right second passenger seat shoulder belt retainer from the right side C-pillar. 8. Remove the (5) screws from the right side C-pillar trim. 9. Remove the (2) screws securing the right side lower trim panel to the C-pillar. 10. Remove the (5) screws securing the D-pillar covers. 11. Lift the right side lower trim panel and roll forward to remove, this exposes the rear HVAC evaporator case module. Page 3942 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3865 Fig.2-Symbols (Part 2 Of 3) Page 3030 Fig.2-Symbols (Part 2 Of 3) Page 844 Coolant Temperature Sensor/Switch (For Computer): Description and Operation Engine Coolant Temperature (ECT) Sensor PURPOSE The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40° C (-40° F) while high temperature causes low resistance (70 ohms at 130° C (266° F). OPERATION The control module supplies a 5 volt signal to the ECT sensor through a resistor in the control module and measures the voltage. The voltage will be high when the engine is cold, and low when the engine is hot. Engine coolant temperature affects most systems controlled by the control module. Page 232 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Ignition Firing Order Page 3395 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3028 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3831 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 1309 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 324 Transfer Case Shift Control Relay Page 3368 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 73 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 452 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 837 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Specifications Throttle Position Sensor: Specifications Idle (normal) ........................................................................................................................................ ....................................................... 0.45 to 0.95 volts (maximum) ........................................................................................................................................... .......................................................... 1.25 volts Wide Open Throttle ............................................................................................................................. ........................................................... 4.0 to 4.5 volts The Throttle position Sensor is not adjustable on this engine but should read below 1.25 volts at closed throttle and about 4.5 volts at wide open throttle. Page 1264 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3671 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 278 Air Bag Control Module: Locations Diagnostic Energy Reserve Module (DERM) Page 2853 Engine Control Module: Description and Operation Powertrain Control Module (PCM) PURPOSE The Powertrain Control Module (PCM) is the control center of the fuel injection system. It constantly looks at the information from various sensors (inputs) and controls the systems (outputs) that affect vehicle performance. The control module also performs the diagnostics of the system. It can recognize operational problems, alert the driver through the Malfunction Indicator Lamp (MIL) "Service Engine Soon" light on the instrument panel and store a Diagnostic Trouble Code(s) (DTC) in the control module memory. The DTC identifies the problem areas to aid the technician in performing repairs. OPERATION The PCM is an electronic computer designed to process the various input information, and send the necessary electrical response to control fuel delivery, spark control, and other emission control systems. The control module can control these devices through the use of Quad Driver Modules (QDM). When the control module is commanding a device or a component "ON," the voltage potential of the output is "LOW" or near zero volts. When the control module is commanding a device or component "OFF," the voltage potential of the circuit will be "HIGH," or near 12 volts. The primary function of the QDM is to supply the ground for the component being controlled. The input information has an interrelation between sensor output. If one of the input devices failed, such as the oxygen sensor, this could affect more than one of the systems controlled by the computer. The PCM has two parts for service: - Controller which is the control module without the PROM (MEM-CAL). - PROM (Programmable Read Only Memory) which is a separate memory calibrator unit LEARNING ABILITY The PCM has a "learning" ability which allows it to make corrections for minor variations in the fuel system to improve driveability. If the battery is disconnected, to clear diagnostic trouble codes or for other repairs. The "learning" process resets and begins again. A change may be noted in the vehicle's performance. To "teach" the vehicle, ensure the engine is at operating temperature. The vehicle should be driven at part throttle, with moderate acceleration and idle conditions until normal performance returns. NOTE: The PCM must be maintained at a temperature below 85°C (185°F) at all times. This is most essential if the vehicle is put through a baking process. The control module will become inoperative if it's temperature exceeds 85°C (185°F). It is recommended that temporary insulation be placed around the control module during the time the vehicle is in a paint oven or other high temperature processes. Page 936 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 192 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Harness View Engine Page 2606 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3235 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Description and Operation Oil Pressure Warning Lamp/Indicator: Description and Operation Many trucks use a warning light on the instrument panel in place of the conventional dash indicating gauge to warn the driver when the oil pressure is dangerously low. The warning light is wired in series with the ignition switch and the engine unit--which is an oil pressure switch. The oil pressure switch contains a diaphragm and a set of contacts. When the ignition switch is turned on, the warning light circuit is energized and the circuit is completed through the closed contacts in the pressure switch. When the engine is started, build-up of oil pressure compresses the diaphragm, opening the contacts, thereby breaking the circuit causing the light to go out. Page 2811 PCM Connector Pin-Out Page 3518 Knock Sensor: Description and Operation PURPOSE: The Knock Sensor (KS) is used to detect engine detonation (ping). OPERATION A 5 volt reference is applied to the knock sensor which has an internal resistance of about 3900 ohms. This resistance will lower the applied voltage to about half or 2.5 volts. When a knock is present, a small AC voltage is produced by the knock sensor and transmitted to the control module riding on top of the already existing 2.5 volts. An AC voltage monitor inside the control module will detect the knock and trigger the control module to start retarding the spark incrementally. A control module (ECM or PCM) is used in conjunction with one or two knock sensors to control detonation. A KS module will be found on ECM applications. On PCM application no KS module will be found as it is internal to the control module. Page 3952 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1782 13. Using template (Figure 5), mark cutting lines on the lower evaporator case using a china marker or equivalent (Figure 1). 14. Cut through the plastic upper evaporator case and the lower evaporator case following the marked outlines of the templates to create two access doors (Figure 1). Do not cut rear edge of either access door (Figure 4 and 5). Use a hot knife or a small (1/2" dia.) rotary abrasive cutting wheel. Page 2672 Temperature Gauge: Testing and Inspection Gauge Reads High 1. Remove lead at sensor, measure resistance using an ohmmeter. 2. At 104 degrees F resistance should be approximately 1200-1350 ohms, and at 125 degrees F resistance should be approximately 53-55 ohms. 3. If resistance is not within specifications, replace sensor. 4. Disconnect lead at sensor and gauge, check for a high resistance using an ohmmeter. Repair wiring if necessary. Page 3239 TP Sensor Circuit Page 1938 Coolant Level Indicator Lamp: Testing and Inspection Indicator Lamp Will Not Illuminate 1. Turn ignition switch to the crank position, and proceed as follows: a. If lamp illuminates, lamp is satisfactory and connector is properly installed. Proceed to step 2. b. If lamp does not illuminate, check bulb, socket and wiring between socket and module connector. Replace or repair as necessary. 2. Turn ignition switch to the On position and disconnect electrical lead at coolant level sensor mounted on the radiator. If lamp fails to illuminate, check wiring between coolant level sensor connector and ECM for a short circuit to ground. If circuit is satisfactory, replace the ECM. Page 2887 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1242 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1733 1992 LB4 VIN Z with "cold knock" only 1992-93 LB4 VIN Z with "cold knock" and installed field fix PROM OR with "cold knock" and detonation 1990-95 LB4 VIN Z Install check valve oil filter P/N 12555891 (FRAM PH3980). If the filter does not cure the condition, install the appropriate calibration from the tables (calibrations are available for all 1992 and some 1993 LB4 applications). If a calibration is not offered or does not cure the short duration cold knock Page 1140 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1056 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3397 Fig.2-Symbols (Part 2 Of 3) Page 491 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Base Idle Speed Idle Speed: Specifications Base Idle Speed Transmission Gear Engine Speed [1] OPEN/CLOSED Loop [2] Manual N 625 +/- 25 CL Automatic D 625 +/- 25 CL [1] If the engine has less than 500 miles or is checked at altitudes above 1500 feet, the idle rpm with a seated IAC valve should be lower than above values. [2] Let engine idle until proper fuel control status (OPEN/CLOSED loop) is reached. Page 1113 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1866 Refrigerant: Technical Service Bulletins A/C - Contaminated R134A Refrigerant Bulletin No.: 06-01-39-007 Date: July 25, 2006 INFORMATION Subject: Contaminated R134a Refrigerant Found on Market for Automotive Air-Conditioning Systems Models: 2007 and Prior GM Passenger Cars and Trucks (including Saturn) 2007 and Prior HUMMER H2, H3 2007 and Prior Saab 9-7X Attention: This bulletin should be directed to the Service Manager as well as the Parts Manager. Commercially Available Contaminated R134a Refrigerant Impurities have been found in new commercially available containers of R134a. High levels of contaminates may cause decreased performance, and be detrimental to some air-conditioning components. Accompanying these contaminates has been high levels of moisture. Tip: Excessive moisture may cause system concerns such as orifice tube freeze-up and reduced performance. Industry Reaction: New Industry Purity Standards Due to the potential availability of these lower quality refrigerants, the Society of Automotive Engineers (SAE), and the Air Conditioning and Refrigeration Industry (ARI) are in the process of instituting reliable standards that will be carried on the labels of future R134a refrigerant containers. This identifying symbol will be your assurance of a product that conforms to the minimum standard for OEM Automotive Air-Conditioning use. How Can You Protect Yourself Today? It is recommended to use GM or ACDelco(R) sourced refrigerants for all A/C repair work. These refrigerants meet General Motors own internal standards for quality and purity, insuring that your completed repairs are as good as the way it left the factory. Parts Information The part numbers shown are available through GMSPO or ACDelco(R). The nearest ACDelco(R) distributor in your area can be found by calling 1-800-223-3526 (U.S. Only). Page 1005 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 673 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 1209 Throttle Position Sensor: Testing and Inspection This check should be performed when TP sensor attaching parts have been replaced. A Tech 1 scan tool can be used to read the TP sensor output voltage, or: 1. Connect digital voltmeter J 39200 or equivalent, from TP sensor connector terminal "B" (BLK wire) to terminal "C" (DK BLU wire). 2. With ignition "ON," engine stopped, the TP sensor voltage should be less than 0.85 volt if more than 0.85 volt verify free throttle movement. If still more than 0.85 volt, replace TP sensor. 3. Remove the voltmeter and jumpers, reconnect the TP sensor connector to the sensor. Page 1246 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 777 Fig.2-Symbols (Part 2 Of 3) Page 3833 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3378 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2884 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3123 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3838 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 859 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 828 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 2607 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Tires - Correct Inflation Pressure Information Tires: All Technical Service Bulletins Tires - Correct Inflation Pressure Information INFORMATION Bulletin No.: 00-00-90-002J Date: January 28, 2009 Subject: Information on Proper Tire Pressure Models: 2010 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2009 and Prior HUMMER H2, H3, H3T 2005-2009 Saab 9-7X Supercede: This bulletin is being revised to add model years and clarify additional information. Please discard Corporate Bulletin Number 00-00-90-002I (Section 00 - General Information). Important: ^ Adjustment of tire pressure for a customer with a Low Tire Pressure Monitor (TPM) light on and no codes in the TPM system is NOT a warrantable repair. Claims to simply adjust the tire pressure will be rejected. ^ ALL tires (including the spare tire) MUST be set to the recommended inflation pressure stated on the vehicle's tire placard (on driver's door) during the PRE-DELIVERY INSPECTION (PDI). Recommended inflation pressure is not the pressure printed on tire sidewall. ^ Tires may be over-inflated from the assembly plant due to the mounting process. ^ Generally a 5.6°C (10°F) temperature change will result in (is equivalent to) a 6.9 kPa (1 psi) tire pressure change. ^ 2008-2009 HUMMER H2 Only - The H2 comes standard with Light Truck "D" Load Range tires with a recommended cold inflation pressure of 289 kPa (42 psi). These tires will alert the driver to a low pressure situation at roughly 262 kPa (38 psi) due to a requirement in FMVSS 138 which specifies a Minimum Activation Pressure for each tire type. This creates a relatively narrow window of "usable" pressure values and the warning will be more sensitive to outside temperature changes during the colder months. As with other cold temperature/tire pressure issues, there is nothing wrong with the system itself. If a vehicle is brought in with this concern, check for tire damage and set all tires to the Recommended Cold Inflation Pressure shown on the vehicle placard. Accurate tire pressures ensure the safe handling and appropriate ride characteristics of GM cars and trucks. It is critical that the tire pressure be adjusted to the specifications on the vehicle¡C■s tire placard during PDI. Ride, handling and road noise concerns may be caused by improperly adjusted tire pressure. The first step in the diagnosis of these concerns is to verify that the tires are inflated to the correct pressures. The recommended tire inflation pressure is listed on the vehicle¡C■s tire placard. The tire placard is located on the driver¡C■s side front or rear door edge, center pillar, or the rear compartment lid. Tip ^ Generally a 5.6°C (10°F) temperature increase will result in (is equivalent to) a 6.9 kPa (1 psi) tire pressure increase. ^ The definition of a "cold" tire is one that has been sitting for at least 3 hours, or driven no more than 1.6 km (1 mi). ^ On extremely cold days, if the vehicle has been indoors, it may be necessary to compensate for the low external temperature by adding additional air to the tire during PDI. ^ During cold weather, the Tire Pressure Monitor (TPM) indicator light (a yellow horseshoe with an exclamation point) may illuminate. If this indicator turns off after the tires warm up (reach operating temperature), the tire pressure should be reset to placard pressure at the cold temperature. ^ The TPM system will work correctly with nitrogen in tires. ^ The TPM system is compatible with the GM Vehicle Care Tire Sealant but may not be with other commercially available sealants. Important: ^ Do not use the tire pressure indicated on the tire itself as a guide. Page 405 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 906 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 2623 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 200 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3768 Fig.1-Symbols (Part 1 Of 3) Page 657 TCC/Stoplamp Switch Wiring Page 2393 Oil Pressure Switch Page 1450 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 3086 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 2195 Warranty Information Tires/Wheels - Tire Puncture Repair Procedures Tires: All Technical Service Bulletins Tires/Wheels - Tire Puncture Repair Procedures INFORMATION Bulletin No.: 04-03-10-001F Date: April 27, 2010 Subject: Tire Puncture Repair Procedures For All Cars and Light Duty Trucks Models: 2011 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 04-03-10-001E (Section 03 - Suspension). This bulletin covers puncture repair procedures for passenger car and light duty truck radial tires in the tread area only. The tire manufacturer must be contacted for its individual repair policy and whether or not the speed rating is retained after repair. Caution - Tire changing can be dangerous and should be done by trained professionals using proper tools and procedures. Always read and understand any manufacturer's warnings contained in their customers literature or molded into the tire sidewall. - Serious eye and ear injury may result from not wearing adequate eye and ear protection while repairing tires. - NEVER inflate beyond 275 kPa (40 pounds) pressure to seat beads. Some run flat tires, such as the Goodyear Extended Mobility Tire (EMT) used on the Corvette, may require more than 275 kPa (40 psi) to seat the bead. In such a case, a tire safety cage must be used. Consult the tire manufacturer for its individual repair policy. - NEVER stand, lean or reach over the assembly during inflation. Repairable area on a radial tire. Important - NEVER repair tires worn to the tread indicators 1.59 mm (2/32") remaining depth). - NEVER repair tires with a tread puncture larger than 6.35 mm (1/4"). - NEVER substitute an inner tube for a permissible or non-permissible repair. - NEVER perform an outside-in tire repair (plug only, on the wheel). - Every tire must be removed from the wheel for proper inspection and repair. - Regardless of the type of repair used, the repair must seal the inner liner and fill the injury. - Consult with repair material supplier/manufacturer for repair unit application procedures and repair tools/repair material recommendations. Three basic steps for tire puncture repair: 1. Remove the tire from the wheel for inspection and repair. Tires/Wheels - Tire Puncture Repair Procedures Tires: All Technical Service Bulletins Tires/Wheels - Tire Puncture Repair Procedures INFORMATION Bulletin No.: 04-03-10-001F Date: April 27, 2010 Subject: Tire Puncture Repair Procedures For All Cars and Light Duty Trucks Models: 2011 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 04-03-10-001E (Section 03 - Suspension). This bulletin covers puncture repair procedures for passenger car and light duty truck radial tires in the tread area only. The tire manufacturer must be contacted for its individual repair policy and whether or not the speed rating is retained after repair. Caution - Tire changing can be dangerous and should be done by trained professionals using proper tools and procedures. Always read and understand any manufacturer's warnings contained in their customers literature or molded into the tire sidewall. - Serious eye and ear injury may result from not wearing adequate eye and ear protection while repairing tires. - NEVER inflate beyond 275 kPa (40 pounds) pressure to seat beads. Some run flat tires, such as the Goodyear Extended Mobility Tire (EMT) used on the Corvette, may require more than 275 kPa (40 psi) to seat the bead. In such a case, a tire safety cage must be used. Consult the tire manufacturer for its individual repair policy. - NEVER stand, lean or reach over the assembly during inflation. Repairable area on a radial tire. Important - NEVER repair tires worn to the tread indicators 1.59 mm (2/32") remaining depth). - NEVER repair tires with a tread puncture larger than 6.35 mm (1/4"). - NEVER substitute an inner tube for a permissible or non-permissible repair. - NEVER perform an outside-in tire repair (plug only, on the wheel). - Every tire must be removed from the wheel for proper inspection and repair. - Regardless of the type of repair used, the repair must seal the inner liner and fill the injury. - Consult with repair material supplier/manufacturer for repair unit application procedures and repair tools/repair material recommendations. Three basic steps for tire puncture repair: 1. Remove the tire from the wheel for inspection and repair. Page 1698 Drive Belt: Technical Service Bulletins Engine - Serpentine Drive Belt Wear Information Bulletin No.: 04-06-01-013 Date: April 29, 2004 INFORMATION Subject: Information on Serpentine Belt Wear Models: 2004 and Prior Passenger Cars and Trucks 2003-2004 and Prior HUMMER H2 All current GM vehicles designed and manufactured in North America were assembled with serpentine belts that are made with an EPDM material and should last the life of the vehicle. It is extremely rare to observe any cracks in EPDM belts and it is not expected that they will require maintenance before 10 years or 240,000 km (150,000 mi) of use. Older style belts, which were manufactured with a chloroprene compound, may exhibit cracks depending on age. However, the onset of cracking typically signals that the belt is only about halfway through its usable life. A good rule of thumb for chloroprene-based belts is that if cracks are observed 3 mm (1/8 in) apart, ALL AROUND THE BELT, the belt may be reaching the end of its serviceable life and should be considered a candidate for changing. Small cracks spaced at greater intervals should not be considered as indicative that the belt needs changing. Any belt that exhibits chunking should be replaced. Disclaimer Page 1402 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Clutch Fluid Leak Fan Clutch: Testing and Inspection Clutch Fluid Leak Small fluid leaks do not generally affect the operation of the unit. These leaks generally occur around the area of the bearing assembly, but if the leaks appear to be excessive, engine overheating may occur. Clutch and fan free-wheeling can cause overheating. To check for clutch and fan free-wheeling, turn the motor "OFF." Spin the fan and clutch assembly by hand. If the fan spins five or more times before it stops, replace the clutch. Page 3787 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Locations Underhood Fuse/Relay Center Page 1986 campaign bulletin before customers take possession of these vehicles. Dealers are to service all vehicles subject to this campaign at no charge to customers, regardless of mileage, age of vehicle, or ownership, from this time forward. Customers who have recently purchased vehicles sold from your vehicle inventory, and for which there is no customer information indicated on the dealer listing, are to be contacted by the dealer. Arrangements are to be made to make the required correction according to the instructions contained in this bulletin. This could be done by mailing to such customers a copy of the appropriate divisional customer letter accompanying this bulletin. Campaign follow up cards should not be used for this purpose, since the customer may not as yet have received the notification letter. In summary, whenever a vehicle subject to this campaign enters your vehicle inventory, or Is in your dealership for service in the future, please take the steps necessary to be sure the campaign correction has been made before selling or releasing the vehicle. Service Procedure 1. Verify the truck is equipped with General Ameri*550 AS LT225/75R16D tires. (Some trucks may come from the factory with General tires on front, and another brand on the rear. Proceed with service procedure on General Tires only. 2. Mark the orientation of the tire to the wheel. 3. Raise the vehicle on the hoist. Check the sidewalls of the tires including the spare for any bulge, if a bulge is found, that tire will need to be replaced. Whether a bulge is found or not, totally deflate all General Tires. 4. Remove the deflated tire/wheel assemblies from the truck. Dismount the tire from the wheel Carefully inspect the tire bead's for any cuts, tears or other damage (See Figure 2). 5. If no damage is found, remount the tire on the wheel using the orientation marks made in Step # 2 and install the tire/wheel assembly on the truck. Torque wheel to specification. Proceed to step # 7. CAUTION: Over tightening of wheel lugs could distort brake rotors resulting brake pulsation. Use an accurate torque wrench and refer to Section 3E-8 Tires and Wheels of the service manual for proper tightening sequence and torque specifications. 6. If damage is found, replace the tire. Mount & balance new tire & install on truck. Torque wheel to specification by following torque procedure specified in step # 5. 7. Install the GM Campaign Identification Label. Page 2677 Temperature Warning Lamp/Indicator: Testing and Inspection If the light is not lit when the engine is being cranked, check for a burned out bulb, an open in the light circuit, or a defective ignition switch. If the light is lit when the engine is running, check the wiring between light and switch for a ground, defective temperature switch, or overheated cooling system. As a test circuit to check whether the bulb is functioning properly, connect a wire from the ground terminal of the ignition switch to the temperature indicator light circuit. When the ignition is in the START (engine cranking) position, the ground terminal is grounded inside the switch and the bulb will be lit. When the engine is started and the ignition switch is in the ON position, the test circuit is opened and the bulb is then controlled by the temperature switch. Page 764 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1022 Oxygen Sensor: Service and Repair Oxygen Sensor NOTE: - The Oxygen Sensor (O2S) has a permanently attached pig-tail and connector. This pig-tail should not be removed, since removal will affect proper operation of the O2S. - Take care when handling the O2S. The in-line electrical connector and louvered end must be kept free of grease, dirt, or other contaminants. Also, avoid using cleaning solvents of any type. Do not drop or roughly handle the O2S. REMOVE OR DISCONNECT: ^ The O2S may be difficult to remove when engine temperature is below 48°C (120°F). Use caution, since excessive force may damage threads in exhaust manifold or pipe. - Disconnect negative battery cable. - Disconnect electrical connector releasing locking tab. - Using suitable wrench, carefully back out sensor. INSTALL OR CONNECT: IMPORTANT: ^ A special anti-seize compound is used on the 02S threads. The compound consists of liquid graphite and glass beads. The graphite will tend to burn away, but the glass beads will remain, making the sensor easier to remove. ^ New, or service replacement sensors will already have the compound applied to the threads. If a sensor is removed from an engine, and if for any reason it is to be reinstalled, the threads must have anti-seize compound applied before reinstallation. - Coat threads of 02S with anti-seize compound (GM P/N 5613695 or equivalent), if necessary. - Install and torque oxygen sensor to 41 Nm (30 lb.ft.). - Reconnect electrical connector. - Reconnect negative battery cable. Service and Repair Fuel Pressure Release: Service and Repair PROCEDURE: NOTE: A constant bleed feature in the pressure regulator relieves pressure when engine is turned "OFF." - Disconnect negative battery terminal to avoid possible fuel discharge if an accidental attempt is made to start the engine. - Loosen fuel filler cap to relieve tank vapor pressure. - The internal constant bleed feature of the TBI relieves fuel pump system pressure when the engine is turned "OFF." Therefore, NO further pressure relief procedure is required. Page 2189 1992 LB4 VIN Z with "cold knock" only 1992-93 LB4 VIN Z with "cold knock" and installed field fix PROM OR with "cold knock" and detonation 1990-95 LB4 VIN Z Install check valve oil filter P/N 12555891 (FRAM PH3980). If the filter does not cure the condition, install the appropriate calibration from the tables (calibrations are available for all 1992 and some 1993 LB4 applications). If a calibration is not offered or does not cure the short duration cold knock Page 3365 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1918 Instrument Panel Wiring, LH Side Page 3939 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 111 Blower Motor Relay: Service and Repair Blower Motor Relay Resistor Remove or Disconnect 1. Negative battery cable. 2. Instrument panel compartment. 3. Electrical connectors, as necessary. 4. Relay (76) from relay bracket. Install or Connect 1. Relay (76) to relay bracket. 2. Electrical connectors, as necessary. 3. Instrument panel compartment. 4. Negative battery cable. - Check circuit operation. Page 485 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 2260 The dexos (TM) specification and trademarks are exclusive to General Motors, LLC. Only those oils displaying the dexos (TM) trademark and icon on the front label meet the demanding performance requirements and stringent quality standards set forth in the dexos (TM)specification. Look on the front label for any of the logos shown above to identify an authorized, licensed dexos 2(TM) engine oil. GM dexos 2(TM) Engine Oil Specification - dexos 2(TM) is approved and recommended by GM for use in Europe starting in model year 2010 vehicles, regardless of where the vehicle was manufactured. - dexos 2(TM) is the recommended service fill oil for European gasoline engines. Important The Duramax(TM) diesel engine is the exception and requires lubricants meeting specification CJ-4. - dexos 2(TM) is the recommended service fill oil for European light-duty diesel engines and replaces GM-LL-B-025 and GM-LL-A-025. - dexos 2(TM) protects diesel engines from harmful soot deposits and is designed with limits on certain chemical components to prolong catalyst life and protect expensive emission reduction systems. It is a robust oil, resisting degradation between oil changes and maintaining optimum performance longer. Disclaimer Service and Repair Water Pump: Service and Repair Water Pump Replacement. 7.4L/V8-454 Engine 1. Disconnect battery ground cable. 2. Drain coolant from radiator. 3. Remove upper fan shroud. 4. Remove drive belt. 5. Remove fan assembly from engine. 6. Lower radiator and heater hose from the water pump. 7. Remove bypass hose. 8. Remove water pump attaching bolts and water pump, Fig. 16. 9. Reverse procedure to install. Tighten water pump attaching bolts to specifications. Page 182 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Starting - Revised Procedures for Inop Ignition Cylinder Technical Service Bulletin # 73-01-09 Date: 971001 Starting - Revised Procedures for Inop Ignition Cylinder File In Section: 0 - General Information Bulletin No.: 73-01-09 Date: October, 1997 INFORMATION Subject: New Tumblers for Cylinder Recoding, Revised Repair Procedures for Inoperative Ignition Cylinders (Seized/Won't Rotate), Labor Operation/Time Allowances Models: 1995-97 Buick Skylark, Riviera 1995-97 Chevrolet Cavalier 1997 Chevrolet Corvette, Malibu, Venture 1995-97 Oldsmobile Achieva 1997 Oldsmobile Aurora, Cutlass, Silhouette 1995-97 Pontiac Grand Am, Sunfire 1997 Pontiac Grand Prix, Trans Sport 1995-97 Chevrolet and GMC C/K, S/T Models 1996-97 Chevrolet and GMC G, M/L Vans 1996-97 Oldsmobile Bravada The information in this bulletin concerns new designed tumblers for recoding lock cylinders that use double sided reversible keys, revised procedures for servicing ignition lock cylinders that are seized or not able to rotate and revised labor time guide information and allowances. Parts Information Parts are currently available from GMSPO. Warranty Information Page 553 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 819 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Engine, A/T - Shift/Driveability Concerns/MIL ON Air Filter Element: All Technical Service Bulletins Engine, A/T - Shift/Driveability Concerns/MIL ON Bulletin No.: 04-07-30-013B Date: February 01, 2007 INFORMATION Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007 HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X Supercede: This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 04-07-30-013A (Section 07 - Transmission/Transaxle). The use of an excessively/over-oiled aftermarket, reusable air filter may result in: Service Engine Soon (SES) light on Transmission shift concerns, slipping and damaged clutch(es) or band(s) Engine driveability concerns, poor acceleration from a stop, limited engine RPM range The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur. When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared to a like vehicle with an OEM air box and filter under the same driving conditions to verify the concern. The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty. If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and the air induction hose for contamination of oil prior to making warranty repairs. Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not considered to be warrantable repair items. Page 3057 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3151 C Series - 2 Wheel Drive 1994-1995 C/K TRUCK 3A-72 Page 3957 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3004 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 2673 Temperature Gauge: Testing and Inspection Gauge Reads Low 1. Ensure terminals are clean and connections are tight. 2. Remove lead at sensor, measure resistance using an ohmmeter. 3. At 104 degrees F resistance should be approximately 1200-1350 ohms, and at 125 degrees F resistance should be approximately 53-55 ohms. 4. If resistance is not within specifications, replace sensor. Page 3828 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3008 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Diagram Information and Instructions Manifold Absolute Pressure (MAP) Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1565 HD 5-Speed Manual Transmission W/4WD Page 594 Refrigerant Pressure Sensor / Switch: Description and Operation Pressure Cycling Switch COMPONENTS The refrigeration cycle (on and off operation of the compressor) is controlled by a switch that senses the low-side pressure as an indicator of evaporator temperature. The pressure cycling switch is the freeze protection device in the system and senses refrigerant pressure on the suction side of the system. This switch is mounted on a standard service low-side fitting. This switch also provides compressor cutoff during cold weather. OPERATION Additional compressor protection results from the operating characteristics of the low-side pressure cycling system. If a massive discharge occurs in the low side of the system, or the orifice tube becomes plugged, low-side pressures could be insufficient to close the contacts of the pressure switch. In the event of a low charge, insufficient cooling accompanied by rapid compressor clutch cycling will be noticed at high outside (ambient) air temperatures. If replacement of the pressure cycling switch is necessary, it is important to note that this may be done without removing the refrigerant charge. A service fitting is located in the pressure switch fitting. During replacement of the pressure switch. a new O-ring seal must be installed and the switch assembled to 4.5 Nm (40 lb in.). Starting - Revised Procedures for Inop Ignition Cylinder Technical Service Bulletin # 73-01-09 Date: 971001 Starting - Revised Procedures for Inop Ignition Cylinder File In Section: 0 - General Information Bulletin No.: 73-01-09 Date: October, 1997 INFORMATION Subject: New Tumblers for Cylinder Recoding, Revised Repair Procedures for Inoperative Ignition Cylinders (Seized/Won't Rotate), Labor Operation/Time Allowances Models: 1995-97 Buick Skylark, Riviera 1995-97 Chevrolet Cavalier 1997 Chevrolet Corvette, Malibu, Venture 1995-97 Oldsmobile Achieva 1997 Oldsmobile Aurora, Cutlass, Silhouette 1995-97 Pontiac Grand Am, Sunfire 1997 Pontiac Grand Prix, Trans Sport 1995-97 Chevrolet and GMC C/K, S/T Models 1996-97 Chevrolet and GMC G, M/L Vans 1996-97 Oldsmobile Bravada The information in this bulletin concerns new designed tumblers for recoding lock cylinders that use double sided reversible keys, revised procedures for servicing ignition lock cylinders that are seized or not able to rotate and revised labor time guide information and allowances. Parts Information Parts are currently available from GMSPO. Warranty Information Wheels - Chrome Wheel Brake Dust Accumulation/Pitting Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Brake Dust Accumulation/Pitting Bulletin No.: 04-03-10-012B Date: February 01, 2008 INFORMATION Subject: Pitting and Brake Dust on Chrome wheels Models: 2008 and Prior GM Passenger Cars and Trucks (including Saturn) 2008 and Prior HUMMER H2, H3 2005-2008 Saab 9-7X Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 04-03-10-012A (Section 03 - Suspension). Analysis of Returned Wheels Chrome wheels returned under the New Vehicle Limited Warranty for pitting concerns have recently been evaluated. This condition is usually most severe in the vent (or window) area of the front wheels. This "pitting" may actually be brake dust that has been allowed to accumulate on the wheel. The longer this accumulation builds up, the more difficult it is to remove. Cleaning the Wheels In all cases, the returned wheels could be cleaned to their original condition using GM Vehicle Care Cleaner Wax, P/N 12377966 (in Canada, P/N 10952905). When using this product, you should confine your treatment to the areas of the wheel that show evidence of the brake dust build-up. This product is only for use on chromed steel or chromed aluminum wheels. Parts Information Warranty Information Wheel replacement for this condition is NOT applicable under the terms of the New Vehicle Limited Warranty. Disclaimer Page 2353 Oil Pressure Switch (For Fuel Pump): Service and Repair Oil Pressure Switch REMOVE OR DISCONNECT 1. Electrical connector. 2. Oil pressure switch using wrench J 35748. INSTALL OR CONNECT 1. Oil pressure switch. 2. Electrical connector. Page 442 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 2276 EXAMPLE 2: The lower insert is stamped STD (standard) and the upper is stamped 0.0010". The undersize for a STD bearing is 0. Divide 0 by 2 to get 0. Divide 0.0010" by 2 to get 0.0005". Add 0 and 0.0005" together to calculate the bearing undersize, which is 0.0005" in this case. 13. Add the original bearing undersize calculated in step 12 to the clearance measured and written down in step 9. For example, if a clearance of 0.0030" was measured with plastigage in step 9 and the calculated bearing undersize from step 12 was 0.0005", the bearing clearance for that particular main journal is equal to 0.0030" plus 0.0005". The bearing clearance would be 0.0035" in this case. 14. Determine which of the combinations of two sizes of replacement bearings will produce the desired clearance. The two sizes available are 0.001" and 0.002". One insert of each size may be combined to produce an intermediate undersize of 0.0015". Subtract the replacement bearing size from the actual clearance to determine which bearing should be used. The bearing that should be used is the one which gives a clearance closer to 0.0008" than to 0.0028". The clearance must not be less than 0.0008". Using the example from step 11, the actual clearance is 0.0035". Subtracting 0.001" from 0.0035" will give a clearance of 0.0025", just barely within the required range. Subtracting 0.002" from 0.0035" will give a clearance of 0.0015". The 0.002" undersize bearing set would be the one to use in this case since it gives a clearance closer to 0.0008", but not less. 15. Install the replacement upper main bearing insert using tool J 8080. 16. Install the replacement lower main bearing insert in the main bearing cap. Lay a piece of plastigage across the width of the lower main bearing insert (same as step 5). 17. Repeat steps 7, 8 and 9. 18. Measuring the plastigage with the scale on the envelope, verify the clearance of the replacement bearings is within the range of 0.001" to 0.003". 19. Repeat steps 4 through 16 for each main bearing. 20. Thrust the crankshaft forward and backward several times to seat the thrust bearing. 21. Reinstall oil pump; torque to 88 N.m (65 lb ft). 22. Reinstall the oil pan and other hardware. 23. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 24. Install fuel pump fuse, start engine, check for leaks or unusual noises. 25. Road test vehicle, check for leaks or unusual noises. THE FOLLOWING PROCEDURE IS TO BE USED FOR VEHICLES REQUIRING MAIN BEARING REPLACEMENT WITH THE ENGINE OUT OF THE VEHICLE Recommended for K, S and T vehicles. 1. Remove the engine from the vehicle using the appropriate service manual procedure. 2. Mount the engine on an engine stand, flip the engine so the oil pan is facing up. 3. Remove the oil pan. 4. Remove the oil pump and shield. 5. Remove the dipstick tube. 6. Remove one (1) main bearing cap (must do one at a time). 7. Plasti-gage bearing. 8. If the bearing clearance is out of specification (clearance greater than 0.003 inches), remove upper main bearing from the block. 9. Check the size of the original bearing. 10. Determine what combination of new bearings are required to get the clearance in the acceptable range of 0.0008 inches to 0.0028 inches. See steps Page 2177 1992 LB4 VIN Z with "cold knock" only 1992-93 LB4 VIN Z with "cold knock" and installed field fix PROM OR with "cold knock" and detonation 1990-95 LB4 VIN Z Install check valve oil filter P/N 12555891 (FRAM PH3980). If the filter does not cure the condition, install the appropriate calibration from the tables (calibrations are available for all 1992 and some 1993 LB4 applications). If a calibration is not offered or does not cure the short duration cold knock Page 1318 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3405 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 692 Fig. 20 Four Wheel Anti-Lock Brake Wiring Circuit. Four wheel anti-lock brake wiring circuit. Additional Wiring Diagrams For additional Lighting and Horns wiring diagrams, See: Lighting and Horns/Diagrams/Electrical Diagrams Page 1062 Throttle Position Sensor: Description and Operation TP Sensor PURPOSE: The Throttle Position (TP) sensor is connected to the throttle shaft on the throttle body unit. It is a potentiometer with one end connected to 5 volts from the control module and the other to ground. A third wire is connected to the control module to measure the voltage from the TP sensor. As the throttle valve angle is changed (accelerator pedal moved), the output of the TP sensor also changes. At a closed throttle position, the output of the TP signal is low (approximately 0.5 volt). As the throttle valve opens, the output increases so that, at Wide Open Throttle (WOT), the output voltage should be approximately 4.5 volts. By monitoring the output voltage from the TP sensor, the control module can determine fuel delivery based on throttle valve angle (driver demand). Page 3434 Crankshaft Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1561 ^ For 1995-97 vehicles, splice into CKT 241 (BRN) between connectors C120 and C100 (Figure 7). Notice: Connections must be water tight in order to prevent water from entering the circuit and causing damage to the components. 9. On K3 models, install the delay relay, included as part of the wiring harness kit, at the engine side of the bulkhead, adjacent to the existing relay. Mount the new relay with self-drilling fastener, P/N 22510339. Route and secure the relay wire harness behind the right oxygen sensor heat shield. 10. Verify system operation. When shifting the transfer case, you should hear the actuator motor operate. Important: Page 1319 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1043 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 949 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 794 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Service and Repair Braking Sensor/Switch: Service and Repair Stop Lamp Switch Remove or Disconnect 1. Negative battery cable. 2. Retainer from brake pedal pin. 3. Switch by unsnapping from pushrod. 4. Electrical connector from switch. Install or Connect 1. Electrical connector into switch. 2. Switch by snapping it onto pushrod. 3. Retainer onto brake pedal pin. 4 Negative battery cable. Page 2494 Valve Clearance: Adjustments These models have a through bolt instead of a stud and adjusting nut. No adjustment is necessary. Page 3930 Fig.2-Symbols (Part 2 Of 3) Page 3719 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Specifications Temperature Vs Resistance Value Page 3667 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Harness View Engine Page 3725 Coolant Temperature Sensor/Switch (For Computer): Service and Repair Engine Coolant Temperature (ECT) Sensor NOTE: Care must be taken when handling engine coolant temperature sensor. Damage to the Engine Coolant Temperature (ECT) sensor will affect proper operation of the fuel injection system. REMOVAL 1. Disconnect negative battery cable. 2. Drain cooling system below level of sensor. 3. Disconnect electrical connector. 4. Remove ECT sensor. INSTALLATION 1. Install sensor in engine. 2. Connect electrical connector. 3. Refill cooling system. 4. Connect negative battery cable. 4L60-E Neutral Safety Switch: Service and Repair 4L60-E PARK/NEUTRAL BACKUP SWITCH REPLACEMENT/ADJUSTMENT Remove - Apply parking brake. - Shift transmission to neutral. 1. Negative battery cable. 2. Transmission control lever to manual shaft nut 3. Transmission control lever from manual shaft. - Let shift cable and control lever drop out of the way. 4. Wiring harness connector from switch. 5. Switch to transmission bolts. 6. Switch from transmission. - Slide switch from manual shaft. lnstall 1. Install Tool J-41384A to Park Neutral Back Up Switch. Be sure that the two detentes on the switch (where manual shaft is inserted) are lined up with the lower two tabs on tool. Rotate tool until upper locator pin on tool is lined up with locator on switch. 2. Switch to transmission. - Before sliding the switch on to the shaft, it may be necessary to lightly file the outer edge of the manual shaft to remove any burrs from the shaft. 3. Switch to transmission bolts. - Tighten Switch to transmission bolts to 27 Nm (20 lbs. ft.). 4. Remove Tool J-41364-A from switch. 5. Wiring harness connectors to switch. 6. Transmission control lever to manual shaft. 7. Transmission control lever to manual shaft nut. Page 1876 Refrigerant: Fluid Type Specifications A/C Refrigerant Type Refrigerant-134a Page 554 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 571 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3680 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Diagram Information and Instructions Knock Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 484 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1456 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3877 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 915 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1143 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 947 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 406 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2892 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2716 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3749 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids A/C - New PAG Oil Refrigerant Oil: Technical Service Bulletins A/C - New PAG Oil Bulletin No.: 02-01-39-004B Date: November 16, 2005 INFORMATION Subject: New PAG Oil Released Models: 2006 and Prior GM Passenger Cars and Trucks (Including Saturn) 2003-2006 HUMMER H2 2006 HUMMER H3 2005-2006 Saab 9-7X Built With R-134a Refrigeration System All Air Conditioning Compressor Types (Excluding R4 and A6 Type Compressors) Supercede: This bulletin is being revised to change the PAG oil part number used for R4 and A6 compressors with R-134a refrigerant systems. Please discard Corporate Bulletin Number 02-01-39-004A (Section 01 - HVAC). All General Motors vehicles built with R-134a refrigerant systems shall now be serviced with GM Universal PAG Oil (excluding vehicles equipped with an R4 or A6 compressor). R4 and A6 compressors with R-134a refrigerant systems shall use PAG OIL, GM P/N 12356151 (A/C Delco part number 15-118) (in Canada, use P/N 10953486). Important: The PAG oil referenced in this bulletin is formulated with specific additive packages that meet General Motors specifications and use of another oil may void the A/C systems warranty. Use this new PAG oil when servicing the A/C system on the vehicles listed above. Oil packaged in an 8 oz tube should be installed using A/C Oil Injector, J 45037. Refer to the HVAC Section of Service Information for detailed information on Oil Balancing and Capacities. Disclaimer Page 676 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3792 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3065 Knock Sensor Page 2545 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3225 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3069 Fig.1-Symbols (Part 1 Of 3) Page 1398 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 2333 INSPECT - All fittings, connectors, and cooler lines for damage or distortion. INSTALL OR CONNECT NOTICE: Do not use more than 690 kPa (100 psi) air to clean the cooler and lines. Exceeding 690 kPa (100 psi) could damage the cooler or lines. Installing Oil Cooler Line Clip Into Connector - Using your thumb and forefinger, insert the connector clip into one of the three recesses in the connector (C in image). With one end of the clip engaged in the connector slot, use your thumb and rotate the clip around the connector until it snaps into place (D and E in image). NOTICE: Make sure the connector clip engages all three slots in the connector. Failure to properly install the connector clip could cause the oil cooler line to come loose and cause damage to the engine. 1. Oil cooler lines to the oil cooler. TIGHTEN - Oil cooler line fittings to 23 Nm (17 lbs. ft.). 2. Oil cooler lines to the clip or strap. TIGHTEN - Bolt to 6 Nm (53 lbs. in.). 3. Bolt or nut to bracket or clamp. TIGHTEN - Bolt to 9 Nm (80 lbs. in.). - Nut to 13 Nm (115 lbs. in.). 4. New oil filter. - Test the flow of oil through the cooler before connecting the lines. - If the flow is not restricted, connect the oil lines to the connector. - A distinct "snap" should be heard when assembling the oil cooler line to the quick connector. The oil cooler line must be fully inserted into the quick connector. Check this by applying a forceful pull to the fitting. - If the flow is restricted, replace the radiator. 5. Run the engine and check for leaks. Page 1995 2. Fill the injury (puncture) to keep moisture out. 3. Seal the inner liner with a repair unit to prevent air loss. External Inspection 1. Prior to demounting, inspect the tire surface, the valve and the wheel for the source of the leak by using a water and soap solution. Mark the injured area and totally deflate the tire by removing the valve core. 2. Demount the tire from the wheel and place the tire on a well-lighted spreader. Internal Inspection 1. Spread the beads and mark the puncture with a tire crayon. 2. Inspect the inner tire for any signs of internal damage. 3. Remove the puncturing object, noting the direction of the penetration. 4. Probe the injury with a blunt awl in order to determine the extent and direction of the injury. 5. Remove any loose foreign material from the injury. 6. Punctures exceeding 6.35 mm (1/4") should not be repaired. Cleaning 1. Clean the area around the puncture thoroughly with a proper liner cleaner, clean cloth and a scraper. This step serves to remove dirt and mold lubricants to insure proper adhesion and non-contamination of the buffing tool. 2. Refer to information on the product or manufacturer's Material Safety Data Sheet and follow guidelines for handling and disposal. Clean the Injury Channel Page 3775 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3076 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1053 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3470 4. Locate the surface for the cylinder release button on the plastic ignition switch housing and center punch a location on the "rib" approximately 3/8" rearward (toward the key entry end) from the cylinder release button, see Figure 3. 5. Using a 1/8" drill bit, carefully drill a pilot hole through the plastic housing only. 6. Using a 9/32" drill bit, carefully drill a larger hole at the pilot location, and slightly into the lock cylinder surface to break the release button retaining spring. 7. Remove portions of the broken spring from the hole using a small pair of needle nose pliers (or other suitable tool) and turn switch over to shake out the release button. 8. Grasp the lock cylinder, remove it from the switch housing. 9. Remove any plastic "flash" from the drilling operations and, using compressed air, blow out the ignition switch assembly. 10. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 11. Install the new cylinder(s) as required by rotating both the cylinder and ignition switch to the "ON" position and pushing the cylinder into the switch. It may be necessary to depress the release button slightly as it passes by the 9/32" hole previously drilled in the housing. 12. Reassemble the ignition switch and instrument panel components as indicated by the appropriate Service Manual. Wheels - Plastic Wheel Nut Covers Loose/Missing Wheel Fastener: All Technical Service Bulletins Wheels - Plastic Wheel Nut Covers Loose/Missing Bulletin No.: 01-03-10-009A Date: July 27, 2004 TECHNICAL Subject: Plastic Wheel Nut Covers Missing and/or Loose (Replace Missing Covers and Add Sealant to All Covers) Models: 2005 and All Prior Passenger Cars (Except All Cadillac Models and Pontiac GTO) with Plastic Wheel Nut Covers Supercede: This bulletin is being revised to add additional models years. Please discard Corporate Bulletin Number 01-03-10-009. Condition Some customers may comment that the plastic wheel nut covers are missing and/or loose. Correction Important: ^ DO NOT USE a silicone-based adhesive. ^ Do not apply the *permatex(R) around the threads in a circular pattern. ^ Apply a single bead across the threads approximately 10 mm (0.4 in) in length, 5 mm (0.2 in) in height and 5 mm (0.2 in) in width. Replace any missing plastic wheel nut covers with the appropriate covers and apply Permatex(R) # 2 Form A Gasket Sealant(R) to the threads of all the plastic wheel nut covers. Tighten finger tight plus a 1/4 turn with a hand wrench. *We believe this source and their products to be reliable. There may be additional manufacturers of such material. General Motors does not endorse, indicate any preference for or assume any responsibility for the products from this firm or for any other such items which may be available from other sources. Permatex(R) # 2 Form A Gasket Sealant(R) part numbers (available at your local parts supplier) ^ P/N 80009 (2A/2AR) - 44 ml (1.5 oz) tube boxed ^ P/N 80015 (2AR) - 44 ml (1.5 oz) tube carded ^ P/N 80010 (2B/2BR) - 89 ml (3 oz) tube boxed ^ P/N 80016 (2BR) - 89 ml (3 oz) tube carded ^ P/N 80011 (2C) - 325 ml (11 oz) tube boxed Warranty Information For vehicles repaired under warranty, use the table. Page 3505 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Component Locations Vehicle Speed Sensor: Component Locations HD Electronic 4-Speed Automatic Overdrive Transmission Page 228 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 716 1. Remove push nail from upper forward area of door panel (Figure 1). 2. Place shim on push nail stem (Figure 2). 3. Install push nail on door panel. Parts Information P/N Description Qty 15730041 Shim, Gray 1 15730042 Shim, Navy Blue 1 15730043 Shim, Ruby Red 1 Page 2121 Wheel Bearing: Service and Repair Rear Dana/Spicer Full Floating Axle REAR WHEEL BEARINGS 1. Raise and support vehicle. 2. Remove axle shaft. 3. Remove hub and drum. 4. Remove oil seal, inner bearing and retaining ring. 5. Remove outer bearing. 6. Reverse procedure to install. Bearing & Cup REAR HUB AND/OR BEARINGS Fig. 7 Removing Outer Bearing & Cup 1. Using a hammer and suitable drift, drive inner bearing, cup and seal from hub assembly. 2. Remove outer bearing snap ring using suitable pliers. 3. Using tools J-24426 and J-8092, Fig. 7, drive outer bearing and cup from hub assembly. 4. Install new outer bearing into hub assembly. 5. Install outer bearing cup using tools mentioned in Step 3. Drive cup beyond snap ring groove. Install outer bearing cup with tool J-8092 positioned upside down to prevent chamfer on tool from damaging cup. 6. Install snap ring into groove using suitable pliers. 7. Using tool J-24426, drive cup against snap ring. 8. Install inner bearing cup using tools J-24427 and J-8092. Drive cup into position until it seats against shoulder of hub bore. 9. Install new oil seal. Hub & Drum REAR HUB AND/OR BEARINGS Fig. 6 Removing Or Installing Wheel Bearing Adjusting Nut 1. Remove wheel and axle shaft. 2. Disengage tang of locknut from slot or flat of locknut, then remove locknut from housing tube, using appropriate tool, Fig. 6. 3. Disengage tang of locknut from slot or flat of adjusting nut and remove locknut from housing tube. 4. Use appropriate tool, Fig. 6, to remove adjusting nut from housing tube. Remove thrust washer from housing tube. Page 2873 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1397 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Stepper Motor Cruise Control - Will Not Resume/Reset Cruise Control Module: All Technical Service Bulletins Stepper Motor Cruise Control - Will Not Resume/Reset FILE IN SECTION: 9 - Accessories BULLETIN NO.: 56-90-02A DATE: July, 1995 SUBJECT: Stepper Motor Cruise Control will not Resume or Reset (Replace SMCC Module) MODELS: 1993-95 Chevrolet Camaro 1993-95 Pontiac Firebird with 3.4L V6 Engine (VIN S - RPO L32) and Automatic Transmission (M30) only OR with 5.7L V8 Engine (VIN P - RPO LT1) and any Transmission 1994-95 Chevrolet and GMC Truck C/K, S/T, M/L Models This bulletin is being revised to add F car information. Please discard Corporate Bulletin Number 56-90-02 (Section 9 - Accessories). CONDITION Some owners may comment that the Stepper Motor Cruise Control (SMCC) will intermittently cut out and will not resume or reset unless the ignition key is cycled. CAUSE The SMCC is sensitive to any brake switch contact bounce of less than 32 milliseconds. This contact bounce may cause the SMCC to go into a diagnostic shut down mode until the module is reset by turning the ignition off. For trucks, the 1994 Zero Adjust Brake switches tend to aggravate this sensitivity. CORRECTION Replace the SMCC module only if the diagnosis in the Service Manual, Section 8A Cruise Control does not resolve the concern. Service Procedure For 1994-95 Chevrolet and GMC Truck C/K, S/T, M/L Models: Follow the SMCC MODULE remove and install procedure using the appropriate service manual. For F-car models, use the following procedure. Remove Before removing cruise control module, disconnect cruise control cable to obtain the necessary clearance. 1. Disconnect cruise control cable end fitting from throttle body lever stud. If vehicle is equipped with accelerator control/cruise control cable adjuster (throttle relaxer), remove cruise control cable end fitting from adjuster. Note location of pulley for end fitting. 2. Unlock cruise control cable conduit by pulling up on unlock button. 3. Push conduit together to obtain the additional cable slack. 4. Remove cruise control module per Section 9B of the Service Manual. Important: It is not necessary to remove cruise control cable from vehicle. Install 1. Install cruise control cable to cruise control module per Section 9B of the Service Manual, Page 868 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3075 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3640 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 662 Fig.2-Symbols (Part 2 Of 3) Page 2711 Coolant Temperature Sensor/Switch (For Computer): Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1208 Throttle Position Sensor: Description and Operation TP Sensor PURPOSE: The Throttle Position (TP) sensor is connected to the throttle shaft on the throttle body unit. It is a potentiometer with one end connected to 5 volts from the control module and the other to ground. A third wire is connected to the control module to measure the voltage from the TP sensor. As the throttle valve angle is changed (accelerator pedal moved), the output of the TP sensor also changes. At a closed throttle position, the output of the TP signal is low (approximately 0.5 volt). As the throttle valve opens, the output increases so that, at Wide Open Throttle (WOT), the output voltage should be approximately 4.5 volts. By monitoring the output voltage from the TP sensor, the control module can determine fuel delivery based on throttle valve angle (driver demand). Diagram Information and Instructions Air Flow Meter/Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1797 leak. - It is important to use the proper wrenches when making connections on O-ring seal fittings. The use of improper wrenches may damage the connection. The opposing fitting should always be backed up with a wrench to prevent distortion of connecting lines or components. When connecting the flexible hose connections, it is important that the swaged fitting and the flare nut, as well as the coupling to which it is attached, be held at the same time using three different wrenches to prevent turning the fitting and damaging the seat. - Tighten tubing connections to the specified torque. Page 1042 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 1738 12 through 14 in the "in-vehicle" service outlined above. 11. Reinstall the upper main bearing. 12. Reinstall the main cap and lower bearing; torque to 110 N.m (80 lb ft). 13. Repeat for each main bearing. 14. Reinstall oil pump and shield; torque to 88 N.m (65 lb ft). 15. Reinstall dipstick tube. 16. Reinstall oil pan. 17. Reinstall engine in vehicle. 18. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 19. Install fuel pump fuse, start engine, check for leaks or unusual noises. 20. Road test vehicle, check for leaks or unusual noises. Correction Category B: Valve Train Clatter, Tick or Click For 1992-94 vehicles equipped with a 4.3L V6 (LB4 VIN Z or L35 VIN W) engine see Corporate Bulletin 376006 for information on converting from net lash to adjustable lash and/or re-lashing the valves on an adjustable lash system. Investigation of "cold knock" is continuing. Updates will continue to be provided when available. Parts Information Check-Valve Filters Description Part Number V6, V8 (Four-Wheel Drive) FRAM PH3980 12555891 V8 (Two-Wheel Drive), Mark V8 PF1218 25160561 The FRAM PH3980 is to be used in place of the PF52. The PH3980 provides superior anti-drainback performance, a key factor in reducing cold knock. FRAM filters are to be procured locally until 08-15-95. After this date the filters may be ordered from GMSPO using the supplied part number. Orders placed to GMSPO prior to this date will not be placed on backorder. Bearings Description Part Number 0.001" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 10120992 0.001" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 10120994 0.002" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 12329758 0.002" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 12329792 Main bearing kits are currently available from GMSPO. All calibrations are currently available from GMSPO. Page 2009 ^ Always inspect and adjust the pressure when the tires are cold. ^ Vehicles that have different pressures for the front and the rear need to be adjusted after tire rotation. Improper tire inflation may result in any or all of the following conditions: ^ Premature tire wear ^ Harsh ride ^ Excessive road noise ^ Poor handling ^ Reduced fuel economy ^ Low Tire Pressure Monitor (TPM) Light ON ^ Low Tire Pressure Message on the Drivers Information Center (DIC) Disclaimer Page 1280 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3214 Throttle Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1197 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2958 Camshaft Position Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3487 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 83 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3401 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Engine - Cold Knock, Replace Oil Filter/Bearings/PROM Oil Filter: All Technical Service Bulletins Engine - Cold Knock, Replace Oil Filter/Bearings/PROM File In Section: 6 - Engine Bulletin No.: 37-61-05A Date: October, 1995 Subject: Cold Engine Knock (Replace Oil Filter/Bearings/PROM) Models: 1990-95 Chevrolet and GMC Truck C/K, R/V, S/T, M/L, G, P Models 1991-92 Oldsmobile Bravada with 4.3L (VIN Z - RPO LB4), 5.7L (VIN K - RPO L05), 7.4 (VIN N - RPO L19) Engine This bulletin is being revised to add the 1995 model year information. Please discard Corporate Bulletin Number 37-61-05 (Section 6 - Engine). Condition Some late model truck engines have been reported to exhibit "cold knock" on start up. "Cold Knock" usually occurs after the vehicle has been completely warmed up, then parked for 8 or more hours in ambient temperatures of 35° F or less. "Cold knock" can be separated into three distinct categories. 1. Short Duration - Harsh, deep metallic knock that usually lasts from 1 to 10 seconds. Generally classified as a bearing or rod knock. 2. Valve Train - Light clatter, tick or click that may last up to 1 minute. 3. Piston Slap - Metallic knock that occurs only under load. Piston slap may last as long as 5 minutes. Correction Category A: Short Duration Knock This matrix describes the repair for each affected model year and engine. Specific information for each affected model year and engine is supplied. Page 871 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1697 Disclaimer Page 1442 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Gauge Does Not Move From Cold When Engine Is Hot Temperature Gauge: Testing and Inspection Gauge Does Not Move From Cold When Engine Is Hot This condition is generally caused by a blown fuse, open circuit or faulty sensor. 1. Check fuse, replace if necessary. 2. Turn ignition switch to On position, then remove lead at sensor unit. 3. Connect test lamp from sensor lead to ground, lamp should glow. Short sensor lead to ground, gauge should indicate "Hot." 4. If gauge indicated HOT, check lead on sensor. If satisfactory, replace sensor. If gauge indicates COLD, replace cluster. Page 877 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 763 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. A/T - 4L80-E 2nd Gear only After A Cold Start/DTC 87 Control Module: All Technical Service Bulletins A/T - 4L80-E 2nd Gear only After A Cold Start/DTC 87 Bulletin No.: 67-71-53B Date: November 10, 2003 TECHNICAL Subject: No Upshift/2nd Gear Only After Cold Start-Intermittent DTC 87-High Ratio Error (Replace EPROM) Models: 1994-1995 Chevrolet and GMC C, K, P Truck, G Van 1996 Chevrolet and GMC P Truck, G Van Equipped with HYDRA-MATIC 4L80E Automatic Transmission (RPO MT1) Supercede: This bulletin is being revised to correct the electronic formatting. There have been no changes to the content of the bulletin. Please discard Corporate Bulletin Number 67-71-53A (Section 7 Transmission). Condition Some owners may comment about no transmission upshift after a cold start. In conjunction, Diagnostic Trouble Code (DTC) 87 is setting intermittently causing the PCM to command the default action of second gear only. Cause The commanded shift to third gear or fourth gear has taken longer than 2 seconds with a minimum 25% TP Sensor reading which has caused DTC 87 to set. Correction If normal diagnostics fail to lead to a resolution or the condition cannot be duplicated, replace the EPROM. Service Information/Procedure Check the PCM for a current or history DTC 87. If DTC 87 is present, refer to the appropriate Service Manual for diagnosis of DTC 87. Refer to corporate bulletin # 577115 for additional information on diagnosing DTC 87. If the diagnosis fails to lead to a resolution and DTC 87 only sets after a cold start, replace the EPROM. Refer to the appropriate Service Manual for EPROM replacement. It is a good idea to verify the new EPROM I.D. with a scan tool against the application listed below. The service EPROM raises the DTC 87 shift time parameter to 4 seconds and the code enabling temperature to 20°C (68°F). Page 3499 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 651 Electronic 4-Speed Automatic Overdrive Transmission Page 3417 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 2771 Vehicle Ride (Trim) Height Specifications Alignment: Specifications Vehicle Ride (Trim) Height Specifications Vehicle Ride Height Location & Specifications "Z" HEIGHT 1. Lift front bumper of vehicle up approximately 1.5 inches. 2. Gently remove hands and allow vehicle to settle on its own. 3. Repeat this operation twice more for a total of three times. 4. Measure "Z" height, Fig. 1. 5. Push front bumper on vehicle down approximately 1.5 inches. 6. Gently remove hands and allow vehicle to rise on its own. 7. Repeat this operation twice more for a total of three times. 8. Measure "Z" height. 9. Find the average of the high and low measurements. This is the "Z" height. "Z" height should be 3.74 inches. "D" HEIGHT IP Dimmer Control - Proper Setting Dimmer Switch: Technical Service Bulletins IP Dimmer Control - Proper Setting File In Section: 08 - Body and Accessories Bulletin No.: 99-08-42-009 Date: November, 1999 INFORMATION Subject: Proper Setting of I/P Dimmer Control to View PRNDL Display with Automatic Headlamp Control Models: 2000 and Prior All Passenger Cars and Trucks With Automatic Headlamp Control and Electronic PRNDL Display Under certain conditions, if the instrument panel dimmer control is turned relatively low, the PRNDL will not be visible until the automatic headlamp control turns the headlamps off and the daytime running lamps (DRL) are turned back on. Such a condition may be if the vehicle is first started in an environment where the headlamp control turns on the headlamps and then the vehicle is driven out into a brighter environment (for example, when a vehicle is backed out of a dark garage into the bright sunlight). This condition is normal and any repair attempt will not be successful. Demonstrate this condition to the customer using the service lane and then turn the instrument panel dimmer control to a higher setting. This will enable the driver to see the PRNDL display Page 3519 Knock Sensor: Testing and Inspection Knock Sensor Check Page 1047 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Diagram Information and Instructions Knock Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1769 Page 918 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 2075 Important: 3. Mask off all wheel nut mounting surfaces and wheel mounting surfaces. 4. Apply 1-1/2 coats of Permahyd 1:1 Primer 4070. Mix 1:1 with Permahyd Hardener 3070 as per TDS. 5. Allow to flash for 30 minutes. 6. Apply two (2) coats of Permahyd 2:1 Surfacer 5080. Mix 2:1 with Permahyd Hardener 3071 as per TDS. 7. Bake for 60 minutes at 140°F (60°C) or allow to flash for 3 hours at 68°F (20°C). 8. Apply Permahyd Base Coat Series 280/285 as per TDS. 9. Allow to flash 10 to 15 minutes. 10. Apply 1 to 2 coats of Permacron High Solid Clear Coat 8060 as per TDS. 11. Allow to flash 10 minutes. Then bake at 140°F (60°C) for 40 minutes. For more information, contact your SPIES HECKER Jobber. We believe these sources and their products to be reliable. There may be additional manufacturers of such products. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or equipment from these firms or for any such items which may be available from other sources. Wheels - Chrome Wheel Brake Dust Accumulation/Pitting Wheels: All Technical Service Bulletins Wheels - Chrome Wheel Brake Dust Accumulation/Pitting Bulletin No.: 04-03-10-012B Date: February 01, 2008 INFORMATION Subject: Pitting and Brake Dust on Chrome wheels Models: 2008 and Prior GM Passenger Cars and Trucks (including Saturn) 2008 and Prior HUMMER H2, H3 2005-2008 Saab 9-7X Supercede: This bulletin is being revised to add model years. Please discard Corporate Bulletin Number 04-03-10-012A (Section 03 - Suspension). Analysis of Returned Wheels Chrome wheels returned under the New Vehicle Limited Warranty for pitting concerns have recently been evaluated. This condition is usually most severe in the vent (or window) area of the front wheels. This "pitting" may actually be brake dust that has been allowed to accumulate on the wheel. The longer this accumulation builds up, the more difficult it is to remove. Cleaning the Wheels In all cases, the returned wheels could be cleaned to their original condition using GM Vehicle Care Cleaner Wax, P/N 12377966 (in Canada, P/N 10952905). When using this product, you should confine your treatment to the areas of the wheel that show evidence of the brake dust build-up. This product is only for use on chromed steel or chromed aluminum wheels. Parts Information Warranty Information Wheel replacement for this condition is NOT applicable under the terms of the New Vehicle Limited Warranty. Disclaimer Page 3038 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3458 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 301 Parts Information Important: In 1994, the L65 and L56 engines changed fuel injection pumps that required a new EPROM. The current fuel injection pump will service prior models. Be sure to match the EPROM with the proper engine fuel injection pump. Parts are currently available through GMSPO. Warranty Information For vehicles repaired under warranty, use the table. Oversize Availability Piston: Service and Repair Oversize Availability A 0.001 inch oversize piston is available for service use so that proper clearances can be obtained for slightly worn cylinder bores requiring only light honing. In addition, oversizes of 0.020 inch, 0.030 inch and 0.040 inch are available. If the cylinders have less than 0.005 inch taper or wear, they can be reconditioned with a hone and fitted with the 0.001 inch oversize piston. Page 669 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 2911 Ignition Control Module: Description and Operation DI Control Module DESCRIPTION The distributor ignition system has a distributor module with four terminals for the IC system that are connected by the control module. To properly control ignition / combustion timing, the control module needs to know: - Crankshaft position. - Engine speed (rpm). - Engine load (manifold pressure or vacuum). - Atmospheric (barometric) pressure. - Engine coolant temperature. IC SYSTEM The IC system consists of the distributor module, a control module, and connecting wires. The four terminals for IC are lettered in the module. The distributor four terminal connector is lettered A-B-C-D. These circuits perform the following functions: Terminal "A" - Reference Ground Lo This wire may be grounded in the distributor. It makes sure the ground circuit, between the module and control module has no voltage drop which could affect performance. If it is open, it may cause poor performance. Terminal "B" - Bypass At about 400 rpm, the control module applies 5 volts to this circuit to switch spark timing control from the module to the control module. An open or grounded bypass circuit will set a DTC 42 and the engine will be at base timing, plus a small amount of advance built into the module. Terminal "C" - Distributor Reference Hi This provides the control module with rpm and crankshaft position information. Terminal "D" - IC This circuit triggers the module. The control module does not know what the actual timing is, but it does know when it gets the reference signal. It then advances or retards the spark from that point. Therefore, if the base timing is set incorrectly, the engine spark curve will be incorrect. Page 2712 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3638 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1107 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 1810 Clutch Fluid: Fluid Type Specifications Hydraulic Clutch Fluid ........................................................................................................................................................... DOT 3 or DOT 4 Brake Fluid With 4L80-E Transmission HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 1020 Oxygen Sensor: Description and Operation Oxygen Sensor PURPOSE: The Oxygen Sensor (O2S) is essentially a small variable battery; it has the ability to produce a low voltage signal that feeds information on engine exhaust oxygen content to the control module. CONSTRUCTION: The O2 Sensor is constructed from a zirconia/platinum electrolytic element. Zirconia is an electrolyte that conducts electricity under certain chemical conditions. The element is made of a ceramic material and is an insulator when cold. At operating temperature, 315°C (600°F), the element becomes a semiconductor. A platinum coating on the outer surface of the element stimulates further combustion of the exhaust gases right at the surface and this helps keep the element up to the desired temperature. Due to the electrolytic properties of the element the oxygen concentration differences between the reference air and the exhaust gases produce small voltages. OPERATION: A rich exhaust (excessive fuel) has almost no oxygen. When there is a large difference in the amount of oxygen touching the inside and outside surfaces, there is more conduction, and the sensor puts out a voltage signal above 0.6 volt (600 mV). With lean exhaust (excessive oxygen) there is about two percent oxygen in the exhaust. This is a smaller difference in oxygen from the outside surfaces which results in less conduction and a voltage signal below 0.3 volt (300 mV). The voltages are monitored and used by the control module to "fine tune" the air/fuel ratio to achieve the ideal mixture desired. The control module puts out a reference signal of 0.45 volt (450 mV). The reference signal serves two purposes. The first is to run the engine when it is in "Open Loop" mode of operation. When the air/fuel ratio is correct the control module "senses" 450 mV. When the engine is operating with a rich air/fuel ratio there is a reduction of free oxygen in the exhaust stream and the oxygen sensor voltage rises above the reference voltage. When the engine is running lean the voltage drops below the reference voltage due to excess oxygen in the exhaust stream. The oxygen sensor provides the feedback information for the "Closed Loop" operating mode of the fuel delivery system. The oxygen sensor indicates to the control module what is happening in the exhaust. It does not cause things to happen. It is a type of gauge: Low voltage output = lean mixture = high oxygen content in exhaust; high voltage output = rich mixture = low oxygen content in the exhaust. CONDITIONS THAT CAN SET CODES: An open oxygen sensor, should set a DTC 13. A constant low voltage in the oxygen sensor circuit should set a DTC 44. A constant high voltage in the circuit should set a DTC 45. DTC 44 and DTC 45 could also be set as a result of fuel system problems. Refer to "DTC Charts" for conditions that can cause a lean or rich system. Page 1331 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 1916 Instrument Panel Wiring, LH Side Auxiliary Battery Wiring Engine, A/T - Shift/Driveability Concerns/MIL ON Air Filter Element: All Technical Service Bulletins Engine, A/T - Shift/Driveability Concerns/MIL ON Bulletin No.: 04-07-30-013B Date: February 01, 2007 INFORMATION Subject: Automatic Transmission Shift, Engine Driveability Concerns or Service Engine Soon (SES) Light On as a Result of the Use of an Excessively/Over-Oiled Aftermarket, Reusable Air Filter Models: 2007 and Prior GM Cars and Light Duty Trucks 2007 and Prior Saturn Models 2003-2007 HUMMER H2 2006-2007 HUMMER H3 2005-2007 Saab 9-7X Supercede: This bulletin is being revised to add models and model years. Please discard Corporate Bulletin Number 04-07-30-013A (Section 07 - Transmission/Transaxle). The use of an excessively/over-oiled aftermarket, reusable air filter may result in: Service Engine Soon (SES) light on Transmission shift concerns, slipping and damaged clutch(es) or band(s) Engine driveability concerns, poor acceleration from a stop, limited engine RPM range The oil that is used on these air filter elements may be transferred onto the Mass Air Flow (MAF) sensor causing contamination of the sensor. As a result, the Grams per Second (GPS) signal from the MAF may be low and any or all of the concerns listed above may occur. When servicing a vehicle with any of these concerns, be sure to check for the presence of an aftermarket reusable, excessively/over-oiled air filter. The MAF, GPS reading should be compared to a like vehicle with an OEM air box and filter under the same driving conditions to verify the concern. The use of an aftermarket reusable air filter DOES NOT void the vehicle's warranty. If an aftermarket reusable air filter is used, technicians should inspect the MAF sensor element and the air induction hose for contamination of oil prior to making warranty repairs. Transmission or engine driveability concerns (related to the MAF sensor being contaminated with oil) that are the result of the use of an aftermarket reusable, excessively/over-oiled air filter are not considered to be warrantable repair items. Page 3714 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1135 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1471 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3068 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 856 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3264 HD 5-Speed Manual Transmission 5-Speed Manual Transmission Diagrams Idle Air Control Valve, Dist.ignition Control Module Page 1291 A. On G, J and N Models: DO NOT REMOVE THE STEERING COLUMN as indicated in the Service Manual procedure. 1. Remove the tilt lever, upper and lower column covers. 2. Drill hole in module housing as indicated in the illustration using a short drill bit (1/8" followed by 9/32") and 90 degree drill motor or go degree drill attachment to break or access the retaining spring for the lock cylinder button, see Figure 2. 3. Using a pick or needle nose pliers, remove the retaining spring from the hole. 4. Using pliers, grasp and remove the retaining button for the cylinder. 5. Remove the cylinder from the housing. 6. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 7. Install the new cylinder and reinstall the steering column components. B. On U, W, and light duty trucks, follow the Service Manual procedure for keys missing, or cylinders won't rotate. Procedure: Instrument Panel Mounted Switches Important: This new procedure involves drilling a hole through the plastic ignition switch and into the lock cylinder slightly to break or access a cylinder release button retaining spring (similar to G, J and N models). The removal of the broken spring and then the release button will allow the switch to be reused. 1. Remove the necessary trim panels to gain access to the instrument panel mounted switch (refer to information in "Body and Accessories Section, Instrument Panel, Gauges and Consoles"). a. On instrument panel mounted N models (Malibu and Cutlass), the switch and cylinder can be accessed after removing the instrument cluster assembly and positioning the switch/cylinder upward in the cavity for the cluster assembly. b. On Corvette models, the switch and cylinder can be accessed after removing the knee bolster from the lower instrument panel area and positioning the switch/cylinder downward from its location on the instrument panel. 2. Loosen switch from instrument panel and disconnect the electrical connections, BUT NOT the cable connection for BTSI (Brake/Transmission Shift Interlock). 3. Protect the immediate work area with a fender cover or other suitable material. Page 352 11. Install either the original sensor or a new one in the hub and secure the sensor. Ensure that the sensor is seated flush against the hub. 12. Install the rotor, the caliper and the wheel. 13. Place the DVM across the sensor terminals and recheck the voltage while rotating the wheel by hand. The voltage should now read at least 350 ACmV's. Parts Information Warranty Information For vehicles repaired under warranty, use the table. Disclaimer Page 3297 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 2929 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1019 Oxygen Sensor: Electrical Diagrams Oxygen Sensor (O2S) Circuit HO2S Sensor Circuit Page 1160 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1260 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3712 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Locations Diagnostic Connector - Fuel Pump: Locations FUEL PUMP PRIME CONNECTOR The Fuel Pump Prime Connector is located in the Instrument Panel (I/P) harness, approximately 20 cm into the Fuse-Relay Center. NOTE: The OEM service manual does not provide a location image for this component. Page 743 Fig.2-Symbols (Part 2 Of 3) Diagram Information and Instructions Throttle Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1202 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Aluminum Wheels - Refinishing Technical Service Bulletin # 531703A Date: 960501 Aluminum Wheels - Refinishing File In Section: 10 - Body Bulletin No.: 53-17-03A Date: May, 1996 INFORMATION Subject: Aluminum Wheel Refinishing Models: 1991-96 Passenger Cars and Trucks This bulletin is being revised to delete the 1990 model year and add the 1996 model year. Please discard Corporate Bulletin Number 53-17-03 (Section 10 - Body). This bulletin supersedes and cancels all previous service bulletins concerning the refinishing of aluminum wheels. The purpose of this service bulletin is to assist dealerships in repairing the discoloration or surface degradation that has occurred on styled aluminum wheels. This bulletin provides NEW PROCEDURES AND SPECIFIC MATERIALS for the refinishing of painted aluminum wheels or aluminum wheels with discoloration or surface degradation. Important: THE RE-MACHINING OF ALUMINUM WHEELS IS NOT RECOMMENDED. THE RE-CLEAR COATING OF ALUMINUM WHEELS IS NO LONGER RECOMMENDED DUE TO CONCERNS OF REPAIR DURABILITY The new procedure requires the wheel surface be plastic media blasted to remove old paint or clear coat. CHEMICAL STRIPPERS ARE NOT RECOMMENDED. Material Required System 1: DuPont Products 3939-S Cleaning Solvent 615/616 Etching Primer URO 5000 Primer Surfacer IMRON 6000 Basecoat 3440-S IMRON Clear System 2: PPG Products DX533 Aluminum Cleaner DX503 Aluminum Conditioner DP Epoxy Primer Deltron Basecoat (DBC) Concept 2001 Clear Acrylic Urethane System 3: Spies Hecker Permahyd Silicone Remover 7090 Permahyd 1:1 Primer 4070 Permahyd 2:1 Surfacer 5080 Permahyd Base Coat Series 280/285 Permahyd H.S. Clearcoat 8060 Color Selection If the wheels being painted were previously clearcoated aluminum, we would recommend using Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle SILVER WA9967 for a very bright look. As an option to the customer, you may also use body color. For color Door Switch - Dome Light Stays On/Dead Battery/No Start Door Switch: All Technical Service Bulletins Door Switch - Dome Light Stays On/Dead Battery/No Start File In Section: 8 - Chassis/Body Electrical Bulletin No.: 56-82-05 Date: September, 1995 Subject: Dome Lamp Stays On, Dead Battery, No Start (Shim Door Trim Panel Push Nail) Models: 1995 Chevrolet and GMC Truck C/K Models 1995 Topkick/Kodiak Models Condition Dome lamp stays on, with doors closed and headlight rotary wheel in the off position. Cause Dome lamp switch plunger is not pushed in far enough. There is too large a gap between the dome lamp switch plunger and the door panel convex push nail. Correction Shim out door panel push nail with color keyed shims available through GMSPO. Service Procedure Page 1379 A. On G, J and N Models: DO NOT REMOVE THE STEERING COLUMN as indicated in the Service Manual procedure. 1. Remove the tilt lever, upper and lower column covers. 2. Drill hole in module housing as indicated in the illustration using a short drill bit (1/8" followed by 9/32") and 90 degree drill motor or go degree drill attachment to break or access the retaining spring for the lock cylinder button, see Figure 2. 3. Using a pick or needle nose pliers, remove the retaining spring from the hole. 4. Using pliers, grasp and remove the retaining button for the cylinder. 5. Remove the cylinder from the housing. 6. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 7. Install the new cylinder and reinstall the steering column components. B. On U, W, and light duty trucks, follow the Service Manual procedure for keys missing, or cylinders won't rotate. Procedure: Instrument Panel Mounted Switches Important: This new procedure involves drilling a hole through the plastic ignition switch and into the lock cylinder slightly to break or access a cylinder release button retaining spring (similar to G, J and N models). The removal of the broken spring and then the release button will allow the switch to be reused. 1. Remove the necessary trim panels to gain access to the instrument panel mounted switch (refer to information in "Body and Accessories Section, Instrument Panel, Gauges and Consoles"). a. On instrument panel mounted N models (Malibu and Cutlass), the switch and cylinder can be accessed after removing the instrument cluster assembly and positioning the switch/cylinder upward in the cavity for the cluster assembly. b. On Corvette models, the switch and cylinder can be accessed after removing the knee bolster from the lower instrument panel area and positioning the switch/cylinder downward from its location on the instrument panel. 2. Loosen switch from instrument panel and disconnect the electrical connections, BUT NOT the cable connection for BTSI (Brake/Transmission Shift Interlock). 3. Protect the immediate work area with a fender cover or other suitable material. Page 3826 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3717 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Diagram Information and Instructions Brake Light Switch: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 2044 service operation. A simple distraction or time constraint that rushes the job may result in personal injury if the greatest of care is not exercised. Make it a habit to double check your work and to always side with caution when installing wheels. Disclaimer Page 1146 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3137 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2772 Catalytic Converter: Description and Operation Three Way Converter Cutaway DESCRIPTION There are two types of Tree-way Catalytic Converters, Close-Couple and the typical 3-way CAT. Both work the same, the difference is the converter and Y-pipe assembly are one unit on the Close-Couple. PURPOSE The purpose of three-way catalytic converters is to neutralize carbon monoxide, hydrocarbons and oxides of nitrogen in the exhaust gases. This is achieved by converting carbon monoxide and hydrocarbons to carbon dioxide and water. Oxides of nitrogen are converted to nitrogen and water. OPERATION This chemical conversion is caused by the platinum and rhodium metals in the converter. The exhaust gases are forced by these noble metals in the converter, inducing the chemical reaction. The noble metal content is about two grams. OPERATING TEMPERATURE The effective conversion of pollutants begins at an operating temperature of about 250°C (450°F). The ideal operating temperature is 400°C to 800°C (750°F to 1500°F). Engine malfunctions such as misfires can cause the temperature of the converter to increase to more than 1400°C (2500 °F). Such temperatures lead to the complete destruction of the converter through the melting of the substrate material. CAUTION: Using leaded fuel will damage the converter and quickly render it ineffective by coating the noble metals with lead deposits. Drivetrain - Updated Transfer Case Speed Sensor Conn. Speed Sensor: Technical Service Bulletins Drivetrain - Updated Transfer Case Speed Sensor Conn. Bulletin No.: 06-04-21-001 Date: May 17, 2006 INFORMATION Subject: Updated Transfer Case Connector Service Kit Now Available For Transfer Case Speed Sensor Wire Harness Connector that Comes Loose Or Connector Retainer Clip Breaks Models: 2007 and Prior GM Light Duty Trucks 2007 and Prior HUMMER H2, H3 2005-2007 Saab 9-7X with Four-Wheel Drive or All-Wheel Drive Technicians may find that when the transfer case speed sensor wire harness connector is removed, the connector lock flexes/bends and does not return to the original position. The transfer case speed sensor wire harness connector then has no locking device. On older vehicles, the plastic connector retainer becomes brittle and the clip may break as soon as it is flexed. In the past, the only service fix was to install a wire harness connector service pack, P/N 88987183. This repair procedure involved splicing a new service connector with an integral connector lock. This connector service kit is of the same design and was still prone to failure over time. A new connector service repair kit is now available, P/N 15306187, that is an updated design. This new kit should be used whenever the speed sensor wire harness connector requires replacement. Parts Information Disclaimer Drivetrain - Rear Axle Lubricant Compatibility & Usage Fluid - Differential: Technical Service Bulletins Drivetrain - Rear Axle Lubricant Compatibility & Usage File in Section: 04 - Driveline Axle Bulletin No.: 99-04-20-001 Date: June, 1999 INFORMATION Subject: Rear Axle Lubricant Compatibility and Usage Models: 1999 Cadillac Escalade 1988-99 Chevrolet and GMC C/K, G Van and P1-3 Series Models Built after the VIN Breakpoints (C/K) listed. This bulletin is being revised to add the 1999 Model Year, VIN Breakpoint information, and additional text Please discard Corporate Bulletin Number 86-42-04 (Section 4 - Driveline/Axle). This bulletin is being issued to inform dealers about the compatibility and usage of the new Fuel Efficient SAE 75W-90 Synthetic Axle Lubricant, GM P/N 12378261 (In Canada use P/N 10953455), with current axles, and with the non-synthetic axle lubricant, GM P/N 1052271 (In Canada use P/N 10950849), for the rear axles on the above light-duty trucks. Testing has shown that the new synthetic lubricant will chemically attack the Room Temperature Vulcanizing (RTV) sealant. Use only the non-synthetic lubricant, P/N 1052271, in axles using RTV sealant (See 9.5 and 10.5 information below). American Axle and Manufacturing (A.A.M.) has approved the use of the new Fuel Efficient SAE 75W-90 synthetic axle lubricant for rear axles with the following restrictions: ^ All 8.6 inch axles are compatible as originally built. Page 1075 Transmission Range Switch (C2) Page 3477 A. On G, J and N Models: DO NOT REMOVE THE STEERING COLUMN as indicated in the Service Manual procedure. 1. Remove the tilt lever, upper and lower column covers. 2. Drill hole in module housing as indicated in the illustration using a short drill bit (1/8" followed by 9/32") and 90 degree drill motor or go degree drill attachment to break or access the retaining spring for the lock cylinder button, see Figure 2. 3. Using a pick or needle nose pliers, remove the retaining spring from the hole. 4. Using pliers, grasp and remove the retaining button for the cylinder. 5. Remove the cylinder from the housing. 6. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 7. Install the new cylinder and reinstall the steering column components. B. On U, W, and light duty trucks, follow the Service Manual procedure for keys missing, or cylinders won't rotate. Procedure: Instrument Panel Mounted Switches Important: This new procedure involves drilling a hole through the plastic ignition switch and into the lock cylinder slightly to break or access a cylinder release button retaining spring (similar to G, J and N models). The removal of the broken spring and then the release button will allow the switch to be reused. 1. Remove the necessary trim panels to gain access to the instrument panel mounted switch (refer to information in "Body and Accessories Section, Instrument Panel, Gauges and Consoles"). a. On instrument panel mounted N models (Malibu and Cutlass), the switch and cylinder can be accessed after removing the instrument cluster assembly and positioning the switch/cylinder upward in the cavity for the cluster assembly. b. On Corvette models, the switch and cylinder can be accessed after removing the knee bolster from the lower instrument panel area and positioning the switch/cylinder downward from its location on the instrument panel. 2. Loosen switch from instrument panel and disconnect the electrical connections, BUT NOT the cable connection for BTSI (Brake/Transmission Shift Interlock). 3. Protect the immediate work area with a fender cover or other suitable material. Page 2919 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 746 Air Flow Meter/Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 3197 Oxygen Sensor: Electrical Diagrams Oxygen Sensor (O2S) Circuit HO2S Sensor Circuit Diagrams Knock Sensor Module Page 3437 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1861 Engine Oil: Fluid Type Specifications GM Goodwrench motor oil or equivalent for API Service SG or SG/CE of the recommended viscosity. Notes on Engine Oil Viscosity: Engine oil viscosity (thickness) has an effect on fuel economy and cold-weather operation (starting and oil flow). Lower viscosity engine oils can provide better fuel economy and cold weather performance; however a rise in temperature may require higher viscosity engine oils for satisfactory lubrication. Notice: Using oils of any viscosity other than those viscosities recommended could result in engine damage. When choosing an oil, consider the range of temperatures the vehicle is operated in before the next oil change. Then, select the recommended oil viscosity. Page 3042 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 477 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Cooling System, A/C - Aluminum Heater Cores/Radiators Radiator: Technical Service Bulletins Cooling System, A/C - Aluminum Heater Cores/Radiators INFORMATION Bulletin No.: 05-06-02-001A Date: July 16, 2008 Subject: Information On Aluminum Heater Core and/or Radiator Replacement Models: 2005 and Prior GM Passenger Cars and Light Duty Trucks (including Saturn) 2003-2005 HUMMER H2 Supercede: This bulletin is being revised to update the Warranty Information. Please discard Corporate Bulletin Number 05-06-02-001 (Section 06 - Engine/Propulsion System). Important: 2004-05 Chevrolet Aveo (Pontiac Wave, Canada Only) does not use DEX-COOL(R). Refer to the flushing procedure explained later in this bulletin. The following information should be utilized when servicing aluminum heater core and/or radiators on repeat visits. A replacement may be necessary because erosion, corrosion, or insufficient inhibitor levels may cause damage to the heater core, radiator or water pump. A coolant check should be performed whenever a heater core, radiator, or water pump is replaced. The following procedures/ inspections should be done to verify proper coolant effectiveness. Caution: To avoid being burned, do not remove the radiator cap or surge tank cap while the engine is hot. The cooling system will release scalding fluid and steam under pressure if the radiator cap or surge tank cap is removed while the engine and radiator are still hot. Important: If the vehicle's coolant is low, drained out, or the customer has repeatedly added coolant or water to the system, then the system should be completely flushed using the procedure explained later in this bulletin. Technician Diagnosis ^ Verify coolant concentration. A 50% coolant/water solution ensures proper freeze and corrosion protection. Inhibitor levels cannot be easily measured in the field, but can be indirectly done by the measurement of coolant concentration. This must be done by using a Refractometer J 23688 (Fahrenheit scale) or J 26568 (centigrade scale), or equivalent, coolant tester. The Refractometer uses a minimal amount of coolant that can be taken from the coolant recovery reservoir, radiator or the engine block. Inexpensive gravity float testers (floating balls) will not completely analyze the coolant concentration fully and should not be used. The concentration levels should be between 50% and 65% coolant concentrate. This mixture will have a freeze point protection of -34 degrees Fahrenheit (-37 degrees Celsius). If the concentration is below 50%, the cooling system must be flushed. ^ Inspect the coolant flow restrictor if the vehicle is equipped with one. Refer to Service Information (SI) and/or the appropriate Service Manual for component location and condition for operation. ^ Verify that no electrolysis is present in the cooling system. This electrolysis test can be performed before or after the system has been repaired. Use a digital voltmeter set to 12 volts. Attach one test lead to the negative battery post and insert the other test lead into the radiator coolant, making sure the lead does not touch the filler neck or core. Any voltage reading over 0.3 volts indicates that stray current is finding its way into the coolant. Electrolysis is often an intermittent condition that occurs when a device or accessory that is mounted to the radiator is energized. This type of current could be caused from a poorly grounded cooling fan or some other accessory and can be verified by watching the volt meter and turning on and off various accessories or engage the starter motor. Before using one of the following flush procedures, the coolant recovery reservoir must be removed, drained, cleaned and reinstalled before refilling the system. Notice: ^ Using coolant other than DEX‐COOL(R) may cause premature engine, heater core or radiator corrosion. In addition, the engine coolant may require changing sooner, at 30,000 miles (50,000 km) or 24 months, whichever occurs first. Any repairs would not be covered by your warranty. Always use DEX‐COOL(R) (silicate free) coolant in your vehicle. ^ If you use an improper coolant mixture, your engine could overheat and be badly damaged. The repair cost would not be covered by your warranty. Too much water in the mixture can freeze and crack the engine, radiator, heater core and other parts. Page 3834 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3770 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 898 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3128 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 2394 Oil Pressure Switch (For Fuel Pump): Description and Operation PURPOSE: As a back-up system to the fuel pump relay, the fuel pump is also turned ON by the oil pressure switch. OPERATION: When the engine oil pressure reaches about 28 kPa (4 psi), through cranking the oil pressure switch will close to complete the circuit to the fuel pump. Page 1115 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1580 Rear Door Wiring Page 3424 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3020 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3816 Vehicle Speed Sensor Buffer Page 100 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1496 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 543 Fig.1-Symbols (Part 1 Of 3) Page 3219 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1391 Fig.2-Symbols (Part 2 Of 3) Locations Diagnostic Connector - Fuel Pump: Locations FUEL PUMP PRIME CONNECTOR The Fuel Pump Prime Connector is located in the Instrument Panel (I/P) harness, approximately 20 cm into the Fuse-Relay Center. NOTE: The OEM service manual does not provide a location image for this component. Page 3594 Spark Plug: Service and Repair REMOVE OR DISCONNECT Make sure the ignition switch is "OFF." CAUTION: Twist the spark plug boot one-half turn to release It. Pull on the spark plug boot only. Do not pull on the wire or the spark plug lead may be damaged. 1. Spark plug wires and boots. - Label the plug wires. NOTE: These spark plugs have a ceramic Insulator that Is about 1/8 Inch longer than earlier model spark plugs. Be sure to use a spark plug socket that Is deep enough for this longer length spark plug. Failure to do so could cause cracking of the Insulator and arcing In side the spark plug, resulting in engine miss. 2. Spark plugs using a 5/8-inch socket. Inspect Each spark plug for wear and gap. Refer to Testing and Inspection. Spark plugs should be gapped to 0.035 inch. INSTALL OR CONNECT CAUTION: Make sure each plug threads smoothly Into the cylinder head and is fully seated. Cross-threading or failing to fully seat spark plugs can cause overheating of the spark plugs, exhaust blow-by, or thread damage. 1. Spark plugs. Tighten Spark plugs to 15 Nm (11 lbs. ft.). 2. Wire and boot assemblies. Refer to Ignition Cable / Service and Repair for precautions. Page 782 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 786 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 977 1995 P TRUCK 3A-68 Change these steps on facing page: "DTC 45 Will Set When:" 1st bullet: ^ Remains above 750 mV for 61-71 seconds and in "Closed Loop." 3rd bullet: Wheels - Changing Procedures/Precautions Wheels: All Technical Service Bulletins Wheels - Changing Procedures/Precautions INFORMATION Bulletin No.: 06-03-10-010A Date: June 09, 2010 Subject: Information on Proper Wheel Changing Procedures and Cautions Models: 2011 and Prior GM Passenger Cars and Trucks 2010 and Prior HUMMER Models 2005-2009 Saab 9-7X 2005-2009 Saturn Vehicles Attention: Complete wheel changing instructions for each vehicle line can be found under Tire and Wheel Removal and Installation in Service Information (SI). This bulletin is intended to quickly review and reinforce simple but vital procedures to reduce the possibility of achieving low torque during wheel installation. Always refer to SI for wheel lug nut torque specifications and complete jacking instructions for safe wheel changing. Supercede: This bulletin is being revised to include the 2011 model year and update the available special tool list. Please discard Corporate Bulletin Number 06-03-10-010 (Section 03 Suspension). Frequency of Wheel Changes - Marketplace Driven Just a few years ago, the increasing longevity of tires along with greater resistance to punctures had greatly reduced the number of times wheels were removed to basically required tire rotation intervals. Today with the booming business in accessory wheels/special application tires (such as winter tires), consumers are having tire/wheel assemblies removed - replaced - or installed more than ever. With this increased activity, it opens up more of a chance for error on the part of the technician. This bulletin will review a few of the common concerns and mistakes to make yourself aware of. Proper Servicing Starts With the Right Tools The following tools have been made available to assist in proper wheel and tire removal and installation. - J 41013 Rotor Resurfacing Kit (or equivalent) - J 42450-A Wheel Hub Resurfacing Kit (or equivalent) Corroded Surfaces One area of concern is corrosion on the mating surfaces of the wheel to the hub on the vehicle. Excessive corrosion, dirt, rust or debris built up on these surfaces can mimic a properly tightened wheel in the service stall. Once the vehicle is driven, the debris may loosen, grind up or be washed away from water splash. This action may result in clearance at the mating surface of the wheel and an under-torqued condition. Caution Before installing a wheel, remove any buildup on the wheel mounting surface and brake drum or brake disc mounting surface. Installing wheels with poor metal-to-metal contact at the mounting surfaces can cause wheel nuts to loosen. This may cause a wheel to come off when the vehicle is moving, possibly resulting in a loss of control or personal injury. Whenever you remove the tire/wheel assemblies, you must inspect the mating surfaces. If corrosion is found, you should remove the debris with a die grinder equipped with a fine sanding pad, wire brush or cleaning disc. Just remove enough material to assure a clean, smooth mating surface. The J 41013 (or equivalent) can be used to clean the following surfaces: - The hub mounting surface - The brake rotor mounting surface - The wheel mounting surface Use the J 42450-A (or equivalent) to clean around the base of the studs and the hub. Lubricants, Grease and Fluids Page 3267 Electronic 4-Speed Automatic Overdrive Transmission Locations Instrument Panel Wiring, LH Side Page 1478 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 3236 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 403 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1261 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 1867 Disclaimer Diagram Information and Instructions Knock Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3731 Fig.1-Symbols (Part 1 Of 3) Page 3641 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3730 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 1343 Knock Sensor: Service and Repair REMOVE OR DISCONNECT 1. Negative battery cable. 2. Drain cooling system. NOTE: On knock sensors which are mounted in the end of the cylinder head draining the cooling system will not be necessary. 3. Wiring harness connector from knock sensor. 4. Knock sensor from cylinder head or block. INSTALL OR CONNECT 1. Knock sensor into cylinder head or block. Apply water base caulk to sensor threads. Do not use silicon tape as this will insulate sensor from engine block. Tighten to 19 Nm (14 lb. ft.). 2. Wiring harness connector to the knock sensor. 3. Negative battery cable. 4. Refill cooling system if required. Page 3777 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 2858 Idle/Throttle Speed Control Unit: Adjustments Idle Speed Control Actuator Adjustment Procedure: - Before adjusting ISC actuator you must first check the minimum idle speed to be within specifications. Refer to SPECIFICATIONS/IDLE SPEED. (ISC actuator must have vacuum applied so that it is not contacting the throttle lever.) See image VIEW A. - Remove vacuum hose on ISC actuator on warm engine. - Adjust ISC actuated idle speed to 1300 +/- 50 rpm. See image VIEW B. - Install vacuum hose. Page 3206 Throttle Position Sensor: Locations Component View Throttle Position (TP) Sensor The Throttle Position (TP) Sensor is attached to the right hand side of the throttle body. Page 905 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Specifications Engine Oil Pressure: Specifications Normal Oil Pressure, psi .............................................................................................................. 10 psi @ 500 RPM minimum; 40-60 psi @ 2000 RPM. Page 1139 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 582 Oil Pressure Switch (For Fuel Pump): Description and Operation PURPOSE: As a back-up system to the fuel pump relay, the fuel pump is also turned ON by the oil pressure switch. OPERATION: When the engine oil pressure reaches about 28 kPa (4 psi), through cranking the oil pressure switch will close to complete the circuit to the fuel pump. Page 904 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3796 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Locations Brake Switch (Cruise Control): Locations Instrument Panel Wiring, LH Side Page 461 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Locations Underhood Fuse/Relay Center Page 1664 Spark Plug Wire: Testing and Inspection VISUAL INSPECTION 1. Inspect the routing of the wires. Improper routing can cause crossfiring. 2. Inspect each wire for any signs of cracks or splits in the wire. 3. Inspect each boot for signs of tears, piercing, arc through, or carbon tracking. If the boot needs to be replaced, twist it a half-turn in either direction to break the seal before pulling on the boot to remove the wire. SPARK PLUG WIRE RESISTANCE TEST 1. Disconnect both ends of each wire. Make sure the wire terminals are clean. 2. Set J 39200 on the high scale and connect it to each end of the wire being tested. Twist the wire gently while watching J 39200. 3. If J 39200 reads above 30,000 ohms (no matter how long the wire is), or fluctuates from infinity any value, replace the wire. 4. If the resistance of any wire is not within the following ranges, replace the wire being tested. - 0 to 381 mm (0 to 15 in.) wire - 3,000 to 10,000 ohms. - 381 mm to 635 mm (15 in. to 25 in.) wire - 4,000 to 15,000 ohms. - 635 mm to 889 mm (25 in. to 35 in.) wire - 6,000 to 20,000 ohms. - Longer wire - should measure about 5,000 to 10,000 ohms per foot. Page 726 Harness Connector Faces Locations Engine Page 1884 Refrigerant Oil: Fluid Type Specifications REFRIGERANT OIL TYPE - R-134a PAG (Polyalkaline Glycol) synthetic refrigerant oil (GM Part No. 12345923) or equivalent. Page 3369 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 2666 Coolant Level Indicator Lamp: Testing and Inspection Indicator Lamp Will Not Illuminate 1. Turn ignition switch to the crank position, and proceed as follows: a. If lamp illuminates, lamp is satisfactory and connector is properly installed. Proceed to step 2. b. If lamp does not illuminate, check bulb, socket and wiring between socket and module connector. Replace or repair as necessary. 2. Turn ignition switch to the On position and disconnect electrical lead at coolant level sensor mounted on the radiator. If lamp fails to illuminate, check wiring between coolant level sensor connector and ECM for a short circuit to ground. If circuit is satisfactory, replace the ECM. Diagram Information and Instructions Crankshaft Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1341 Knock Sensor: Testing and Inspection Knock Sensor Check Page 3282 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 439 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Diagram Information and Instructions Oxygen Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3046 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 1922 Fuse Block: Application and ID Underhood Fuse/Relay Center Underhood Fuse/Relay Center Page 3576 Spark Plug Wire: Testing and Inspection VISUAL INSPECTION 1. Inspect the routing of the wires. Improper routing can cause crossfiring. 2. Inspect each wire for any signs of cracks or splits in the wire. 3. Inspect each boot for signs of tears, piercing, arc through, or carbon tracking. If the boot needs to be replaced, twist it a half-turn in either direction to break the seal before pulling on the boot to remove the wire. SPARK PLUG WIRE RESISTANCE TEST 1. Disconnect both ends of each wire. Make sure the wire terminals are clean. 2. Set J 39200 on the high scale and connect it to each end of the wire being tested. Twist the wire gently while watching J 39200. 3. If J 39200 reads above 30,000 ohms (no matter how long the wire is), or fluctuates from infinity any value, replace the wire. 4. If the resistance of any wire is not within the following ranges, replace the wire being tested. - 0 to 381 mm (0 to 15 in.) wire - 3,000 to 10,000 ohms. - 381 mm to 635 mm (15 in. to 25 in.) wire - 4,000 to 15,000 ohms. - 635 mm to 889 mm (25 in. to 35 in.) wire - 6,000 to 20,000 ohms. - Longer wire - should measure about 5,000 to 10,000 ohms per foot. Page 3690 Coolant Temperature Sensor/Switch (For Computer): Locations Component View Engine Coolant Temperature (ECT) Sensor The Engine Coolant Temperature (ECT) Sensor is located on the intake manifold next to the thermostat housing. Page 1400 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 1488 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 2813 PCM Connector Pin-Out Page 1869 Disclaimer Page 1227 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 361 Notice: Cut through plastic case material only. Aluminum tubes are located approximately 1/8" behind the case wall (Figure 2, view 1). Do not use a larger diameter cutting wheel. 15. Using a heat gun to soften the plastic case, pull back the access door on the upper evaporator case carefully to prevent breaking the case. Reach in carefully and remove the holding clamp securing the capillary tube to the evaporator outlet tube. Be careful not to damage the capillary tube. Discard clamp. 16. Using a heat gun to soften the plastic case, pull back the access door on the lower evaporator case carefully to prevent breaking the case (Figure 2). Reach in carefully with two small adjustable wrenches and loosen the fitting attaching the TXV to the evaporator inlet tube. It will require a 7/8" crows foot extension to loosen the TXV outlet joint fitting hidden behind the TXV itself. Remove and discard the TXV. 17. Remove original O-rings from the evaporator tubes and replace with new O-rings that have been oiled with 525 viscosity refrigerant mineral oil. DO NOT USE PAG LUBRICANT. 18. Install the new TXV to the evaporator tubes being careful not to damage the O-rings. Finger tighten the joints and then torque the joints, using a backup wrench to hold the TXV in position to: INLET 20-35 Nm (14-25 lb.ft.) OUTLET 15-22 Nm (11-16 lb.ft.) Service and Repair Oil Pan: Service and Repair 1. Disconnect battery ground cable. 2. Loosen fan shroud, then remove air cleaner assembly. 3. Remove distributor cap. 4. Raise and support vehicle, then drain oil pan. 5. On models equipped with manual transmission, remove starter. 6. Remove torque converter or clutch cover as applicable. 7. Remove oil filter. 8. If equipped with oil pressure gauge, disconnect oil pressure line from side of cylinder block to prevent damaging line. 9. Remove engine mount through bolts, then raise engine. 10. Remove oil pan attaching bolts, then the oil pan. 11. Reverse procedure to install, noting the following: a. Apply sealant approximately 1 inch in both directions from each of the four corners. b. Tighten oil pan attaching bolts to specifications. Specifications Valve Guide: Specifications Valve guides in these engines are an integral part of the head and, therefore, cannot be removed. For service, guide holes can be reamed oversize to accommodate one of several service valves with oversize stems. Check the valve stem clearance of each valve (after cleaning) in its respective valve guide. If the clearance exceeds the service limits of .004 inch on the intake or .005 inch on the exhaust, ream the valve guide to accommodate the next oversize diameter valve stem. Select the reamer for the smallest oversize which will provide a clean straight bore through the valve guide. After reaming, a new seat should be cut into the head to assure perfect seating of the new valve. Page 593 Refrigerant Pressure Sensor / Switch: Description and Operation High Pressure Cut-Off Switch COMPONENTS The system is also equipped with a high pressure cut off switch. This switch is normally closed, and opens at 2827-3103 kPa (410-450 psi) to interrupt the voltage to the compressor clutch coil. This will stop the compressor from cycling and prevent the pressure relief valve from discharging refrigerant and oil. Page 1138 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 775 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2962 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Bearing Undersize Availability Crankshaft Main Bearing: Specifications Bearing Undersize Availability Shell type bearings are used, and if worn excessively, should be replaced. No attempt should be made to shim, file or otherwise take up worn bearings. Main bearings are available in standard and undersizes of .001, .002, .009, .010 and .020 inch. Page 3345 Oil Pressure Switch (For Fuel Pump): Description and Operation PURPOSE: As a back-up system to the fuel pump relay, the fuel pump is also turned ON by the oil pressure switch. OPERATION: When the engine oil pressure reaches about 28 kPa (4 psi), through cranking the oil pressure switch will close to complete the circuit to the fuel pump. Page 2507 Coolant: Technical Service Bulletins Extended Life Engine Coolant - DEX-COOL(TM) FILE IN SECTION: 6 - Engine BULLETIN NO.: 53-62-01 DATE: June, 1995 SUBJECT: New Extended Life Engine Coolant Known as DEX-COOL(TM) MODELS: 1995 Passenger Cars and Trucks A new extended life engine coolant known as "DEX-COOL(TM)" will be used in all General Motors vehicles. Some trucks will be filled with DEX-COOL TM beginning in late May; most vehicles will convert in July, 1995 with the remaining vehicles to convert by January, 1996. Most of these vehicles will be 1995 models. All production for 1996 models will utilize DEX-COOL(TM). It is imperative to note the following about DEX-COOL(TM) engine coolant: ^ IT IS ORANGE IN COLOR TO DISTINGUISH IT FROM CONVENTIONAL COOLANT. ^ THE SERVICE CHANGE INTERVAL ON VEHICLES WHICH ARE BUILT WITH DEX-COOL(TM) IS 5 YEARS/100,000 MILES, WHICHEVER OCCURS FIRST. ^ TO MAINTAIN FULL CORROSION PROTECTION DURABILITY, DEX-COOL (TM) MUST NOT BE MIXED WITH CONVENTIONAL (CONTAINING SILICATE) ENGINE COOLANTS. ^ DEX-COOL(TM) IS AN ETHYLENE GYLCOL BASED PRODUCT, THEREFORE, BOIL AND FREEZE PROTECTION ARE MEASURED IN THE SAME FASHION AS CONVENTIONAL COOLANTS. TO FULLY REALIZE ITS MANY ADVANTAGES, DEX-COOL(TM) MUST NEVER BE MIXED WITH CONVENTIONAL COOLANTS. It is particularly important to top-off new vehicles with DEX-COOL(TM) DEX-COOL(TM) forms a protective film on aluminum surfaces, however, if a vehicle with less than 3,000 miles is topped-off with conventional coolant, aluminum corrosion may occur. DEX-COOL(TM) CAN BECOME CONTAMINATED BY INADVERTENTLY TOPPING-OFF WITH CONVENTIONAL COOLANT, ADDING CONVENTIONAL COOLANT TO THE RADIATOR, OR EVEN IF FILL/DRAIN CONTAINERS ARE SHARED BETWEEN COOLANTS. If contamination occurs on a new vehicle (i.e. during vehicle prep), the cooling system must be immediately drained and refilled with DEX-COOL(TM) If contamination with conventional coolant occurs after the vehicle has been driven for at least 3,000 miles, no short-term problems will occur; however, the service change interval will be reduced from 5 years/100,000 miles to 2 years/30,000 miles. More information on DEX-COOL(TM) engine coolant service procedures can be found in the 1996 Service Manuals and a video tape which will be issued by STG. Vehicles which contain DEX-COOL(TM) can be identified by a special underhood label which states "USE DEX-COOL(TM) COOLANT ONLY. .. meeting Spec. 6277M". They may also be identified by the coolant's orange color and the information contained in the Owner's Manual. REGARDING COOLANT RECYCLING Engine coolant recycling is affected by DEX-COOL(TM) as follows. Used DEX-COOL(TM) can be mixed into your "used" conventional coolant storage vessel and the mixture recycled in the same manner as you are accustomed to. This recycled mixture of conventional and DEX-COOL(TM) coolant must be used as a 2 year/30,000 mile conventional coolant and should not be used in vehicles originally equipped with DEX-COOL(TM) When servicing vehicles originally equipped with DEX-COOL(TM), use only Goodwrench-DEX-COOL(TM) Additional research will be conducted to evaluate the feasibility of recycling DEX-COOL(TM) to DEX-COOL(TM) in the near future. Page 1306 Knock Sensor Page 386 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2342 Oil Pressure Gauge: Testing and Inspection Gauge Reads Low 1. Check oil level, add if necessary. 2. Turn ignition switch to the On position. 3. Remove oil pressure sensor lead at sensor, gauge should read high. 4. If gauge stays low, remove sensor lead at gauge. Gauge should read high. If gauge reads high, locate and repair short to ground between gauge and sensor. 5. If gauge still reads low, replace cluster. 6. With lead removed at sensor, connect an ohmmeter to sensor. With engine stopped resistance should be one ohm, and approximately 44 ohms with engine running. 7. If sensor reads significantly lower than 44 ohms with engine running, replace sensor. Page 446 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 552 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 965 Manifold Absolute Pressure (MAP) Sensor: Testing and Inspection Manifold Absolute Pressure (MAP) Output Check Page 2886 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1816 Processes shown in the Table 3 are capable of recycling waste engine coolants (DEX-COOL(R) or conventional) to a conventional (green) coolant. Recycling conventional coolant can be accomplished at your facility by a technician using approved EQUIPMENT (listed by model number in Table 3), or by an approved coolant recycling SERVICE which may recycle the coolant at your facility or at an offsite operation. Refer to the table for GM approved coolant recyclers in either of these two categories. Should you decide to recycle the coolant yourself, strict adherence to the operating procedures is imperative. Use ONLY the inhibitor chemicals supplied by the respective (GM approved) recycling equipment manufacturer. Sealing Tablets Cooling System Sealing Tablets (Seal Tabs) should not be used as a regular maintenance item after servicing an engine cooling system. Discoloration of coolant can occur if too many seal tabs have been inserted into the cooling system. This can occur if seal tabs are repeatedly used over the service life of a vehicle. Where appropriate, seal tabs may be used if diagnostics fail to repair a small leak in the cooling system. When a condition appears in which seal tabs may be recommended, a specific bulletin will be released describing their proper usage. Water Quality The integrity of the coolant is dependent upon the quality of DEX-COOL(R) and water. DEX-COOL(R) is a product that has enhanced protection capability as well as an extended service interval. These enhanced properties may be jeopardized by combining DEX-COOL(R) with poor quality water. If you suspect the water in your area of being poor quality, it is recommended you use distilled or de-ionized water with DEX-COOL(R). "Pink" DEX-COOL(R) DEX-COOL(R) is orange in color to distinguish it from other coolants. Due to inconsistencies in the mixing of the dyes used with DEX-COOL(R), some batches may appear pink after time. The color shift from orange to pink does not affect the integrity of the coolant, and still maintains the 5 yr/150,000 mile (240,000 km) service interval. Back Service Only use DEX-COOL(R) if the vehicle was originally equipped with DEX-COOL(R). Page 22 For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon the module/component connection that the dielectric lubricant was applied to refer to the table above. Disclaimer Page 3476 The existing labor operation (E7200) has been changed to include "Add" conditions for cylinders that will not rotate. New Tumblers New tumblers are available from GMSPO for recoding lock cylinders that use double-sided reversible keys. These new tumblers should be used immediately and information about the disposition of original tumblers will be provided by GMSPO. Figure 1 shows the new tumbler profile. The shaded area was part of the original tumbler profile, and is removed on the new tumblers. The new part numbers for the tumblers are as follows: Part No. 2852732 = Tumbler # 1 Part No. 2852733 = Tumbler # 2 Part No. 2852734 = Tumbler # 3 Part No. 2852735 = Tumbler # 4 Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. New Procedures For Seized/Won't Rotate Column Mounted Ign. CYL. Page 3240 Throttle Position Sensor: Description and Operation TP Sensor PURPOSE: The Throttle Position (TP) sensor is connected to the throttle shaft on the throttle body unit. It is a potentiometer with one end connected to 5 volts from the control module and the other to ground. A third wire is connected to the control module to measure the voltage from the TP sensor. As the throttle valve angle is changed (accelerator pedal moved), the output of the TP sensor also changes. At a closed throttle position, the output of the TP signal is low (approximately 0.5 volt). As the throttle valve opens, the output increases so that, at Wide Open Throttle (WOT), the output voltage should be approximately 4.5 volts. By monitoring the output voltage from the TP sensor, the control module can determine fuel delivery based on throttle valve angle (driver demand). Page 1410 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 2578 DISCLAIMER Page 87 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1424 - The engine must start in the "P" (Park) or "N" (Neutral) positions only. Adjust if needed. Refer to 'Park Neutral Backup Switch Adjustment." Page 1619 Idle Speed: Specifications Controlled Idle Speed Transmission Gear Idle Speed IAC Counts [1] OPEN/CLOSED Loop [2] Manual N 750 +/- 25 5-30 CL Automatic D 675 +/- 25 5-30 CL [1] On manual transmission vehicles the SCAN tool will display RDL in Neutral. Add 2 counts for engines with less than 500 miles. Add 2 counts for every 1000 ft. above sea level. [2] Let engine idle until proper fuel control status is reached (OPEN/CLOSED loop). Service Precautions Hose/Line HVAC: Service Precautions Proper O-Ring Installation Improper O-Ring Installation IMPORTANT - Before opening the refrigeration system to the atmosphere, make sure the work area is well ventilated. Welding or steam-cleaning operations should not be done on or near refrigeration system lines or other air conditioning parts on the vehicle. - All metal tubing lines should be free of dents or kinks to prevent loss of system capacity due to line restriction. - The flexible hose lines should never be bent to a radius of less than four times the diameter of the hose. - The flexible hose lines should never be allowed to come within a distance of 6.5 mm (2.5 inches) of the exhaust manifold. - Flexible hose lines should be inspected regularly for leaks or brittleness and replaced with new lines if deterioration or leaking is found. - When disconnecting any fitting in the refrigerant system, the system must be discharged of all Refrigerant-134a. However, proceed very cautiously, regardless of the gage readings. Open very slowly, keeping your face and hands away so that no injury can occur, If pressure is noticed when a fitting is loosened, allow it to bleed off very slowly. NOTICE: Alcohol should never be used In the refrigeration system In an attempt to remove moisture. Damage to system components could occur. - If any refrigerant line is opened to the atmosphere, it should be immediately capped to prevent the entrance of moisture and dirt. These contaminants can cause internal compressor wear or plugged lines in the condenser and evaporator core and expansion (orifice) tubes or compressor inlet screens. - Remove sealing caps from subassemblies just before making connections for final assembly. Use a small amount of clean 525 viscosity refrigerant oil on all tube and hose joints. Use new O-ring seals dipped in 525 viscosity refrigerant oil when assembling joints. The oil will aid in assembly and help to provide a leakproof joint. O-ring seals and seats must be in perfect condition because a burr or a piece of dirt can cause a refrigerant Page 240 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3664 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1608 Caster Measures CAMBER 1. Determine the camber from the alignment equipment. 2. Install adjustment kit No. 15538596, or equivalent. 3. Reset camber to specifications. CASTER All caster specifications are given with the vehicle frame level (zero angle). 1. Position vehicle on a smooth level surface. 2. If necessary, correct "Z" height. 3. Using a bubble protractor or inclinometer, measure frame angle, Figs. 1 and 2. 4. Note frame angle as being up in the rear or down in the rear. 5. Determine caster angle from alignment equipment. 6. Determine actual (corrected) caster reading, Fig. 2. 7. When measuring caster, note the following: a. A decrease in rear frame angle must be subtracted from a positive caster reading. b. An increase in rear frame angle must be added to a positive caster reading. c. A decrease in rear frame angle must be added to a negative caster reading. d. An increase in rear frame angle must be subtracted from a negative caster reading. 8. If the caster angle is incorrect, correct the caster angle by turning the adjustment cam bolts. Front Toe Adjustment 1. Determine toe-in from the alignment equipment. 2. Change length of both tie rod sleeves to effect a toe change. 3. Toe-in can be increased or decreased by changing the length of the tie rod ends. A threaded sleeve is provided for this purpose. When the tie rod ends are mounted ahead of the steering knuckle they must be decreased in length in order to increase toe-in. When the tie rod ends are mounted behind the steering knuckle they must be lengthened in order to increase toe-in. Page 1232 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3949 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3316 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 1059 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 671 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 206 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1444 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Brake Fluid - Level & Filling Recommendations Brake Fluid: Technical Service Bulletins Brake Fluid - Level & Filling Recommendations File In Section: 05 - Brakes Bulletin No.: 00-05-22-004 Date: May, 2000 INFORMATION Subject: Brake Fluid Level and Filling Recommendations Models: 2001 and Prior Passenger Cars and Trucks Many dealers and after-market repair shops advertise multi-point fluid "top-ups" in conjunction with oil changes or regular maintenance packages. These offers often include adding brake fluid to the master cylinder reservoir. There are only two reasons why the brake fluid level in the brake reservoir might go down. The first is that the brake fluid level goes down an acceptable level during normal brake lining wear. When the linings are replaced, the fluid will return to it's original level. The second possible reason for a low fluid level is that fluid is leaking out of the brake system. If fluid is leaking, the brake system requires repair and adding additional fluid will not correct the leak. If the system was properly filled during delivery of the vehicle, no additional fluid should be required under most circumstances between brake pad and/or shoe replacements. This information can be reinforced with the customer by referring them to the Brake Fluid section of their vehicle's Owner's Manual. Guidelines GM vehicles have incorporated a variety of brake fluid reservoir styles. The following guidelines are restricted to the plastic bodied fluid reservoirs and do not affect the original service recommendations for the older style metal bodied units. You may encounter both black plastic and translucent style reservoirs. You may have reservoirs with: ^ A MAX fill mark only ^ A MIN fill mark only ^ Both MAX and MIN marks The translucent style reservoirs do not have to have the covers removed in order to view the fluid level. It is a good practice not to remove the reservoir cover unless necessary to reduce the possibility of contaminating the system. Use the following guidelines to assist in determining the proper fluid level. Important: When adding brake fluid, use Delco Supreme II(R) Brake Fluid, GM P/N 12377967 or equivalent brand bearing the DOT-3 rating only. Important: At no time should the fluid level be allowed to remain in an overfilled condition. Overfilling the brake reservoir may put unnecessary stress on the seals and cover of the reservoir. Use the following guidelines to properly maintain the fluid level. If the reservoir is overfilled, siphon out the additional fluid to comply with the guidelines below. Important: If under any circumstance the brake fluid level is extremely low in the reservoir or the BRAKE warning indicator is illuminated, the brake system should be checked for leaks and the system repaired in addition to bringing the fluid level up to the recommended guidelines outlined below. A leaking brake system will have reduced braking performance and will eventually not work at all. Important: Some vehicles have reservoirs that are very sensitive to brake fluid levels and may cause the BRAKE indicator to flicker on turns as the fluid approaches the minimum required level. If you encounter a vehicle with this concern, increase the fluid level staying within the guidelines outlined below. ^ If the reservoir has a MAX level indicator, the reservoir should be returned to the MAX marking only at the time new brake pads and/or shoes are installed. If the reservoir fluid level is at the half-way point or above do not attempt to add additional brake fluid during routine fluid checks. ^ If the reservoir has both MAX and MIN indicators, the fluid level should be maintained above the MIN indicator during routine fluid checks and returned to the MAX indication only after new brake pads and/or shoes are installed. ^ For reservoirs with only a MIN indication, the fluid level should be maintained above the MIN indicator during routine fluid checks. Return the Page 2611 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Description and Operation Coolant Level Indicator Lamp: Description and Operation This system uses a sensor mounted on the radiator and an indicator light mounted in the instrument panel to warn the driver if coolant level is too low. This light is wired in series with the ignition switch, ECM and the sensor. When the ignition switch is turned to the crank position, the circuit is energized and the indicator light will illuminate. When the ignition switch is turned to the ON position and coolant level is sufficient, the sensor will indicate this to the ECM and the light will turn off. Page 175 Engine Control Module: Locations Powertrain Control Module (PCM) Page 3944 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 1188 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3875 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 2706 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 890 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 681 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 2885 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3785 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 2548 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Heater Inlet Hose Heater Hose: Service and Repair Heater Inlet Hose Heater Hose Routing Quick Connect Heater Inlet Connector Remove or Disconnect Tool Required: J 38723 Heater Line Quick Connect Separator or Equivalent 1. Air cleaner. 2. Engine coolant. 3. Inlet hose mounting screw. 4. Inlet hose clamp at heater core. - Loosen the clamp enough to slide the clamp away from the fitting on the inlet hose 5. Inlet hose from heater core. 6. Push inlet hose into connector and insert J 38723 or equivalent into connector to release locking tabs. 7. Pull retainer and hose from heater inlet connector. Inspect - O-ring sealing surface on hose/pipe. Adjust - If replacing heater inlet connector, remove retainer from hose and discard, as new connector is equipped with retainer. Page 1310 Fig.1-Symbols (Part 1 Of 3) Page 233 Fuel Pump Relay: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 2821 Fig.1-Symbols (Part 1 Of 3) Page 1457 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2659 Heater Hose: Service and Repair Heater Outlet Hose Heater Hose Routing Quick Connect Heater Inlet Connector Remove or Disconnect 1. Engine coolant. 2. Hose clamps. 3. Outlet hose clip. 4. Outlet hose from heater core. 5. Outlet hose from radiator. Install or Connect 1. Outlet hose to radiator. 2. Outlet hose to heater core. 3. Outlet hose clip. 4. Hose clamps. 5. Engine coolant. - Check system for leaks. Page 800 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Specifications Spark Plug: Specifications Spark Plug Gap ................................................................................................................................... ............................................. 0.90 mm (0.035 inches) Spark Plug Torque ............................................................................................................................... ...................................................... 15 Nm (11 lb. ft.) Spark Plug Type .................................................................................................................................. .............................................................. AC CR43TS NOTE: Check the gap specifications found on the Emissions Control Label. If the gap is different from what is listed here, use the information on the label. Page 1265 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3810 PCM Connector Pin-Out Page 2182 12 through 14 in the "in-vehicle" service outlined above. 11. Reinstall the upper main bearing. 12. Reinstall the main cap and lower bearing; torque to 110 N.m (80 lb ft). 13. Repeat for each main bearing. 14. Reinstall oil pump and shield; torque to 88 N.m (65 lb ft). 15. Reinstall dipstick tube. 16. Reinstall oil pan. 17. Reinstall engine in vehicle. 18. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 19. Install fuel pump fuse, start engine, check for leaks or unusual noises. 20. Road test vehicle, check for leaks or unusual noises. Correction Category B: Valve Train Clatter, Tick or Click For 1992-94 vehicles equipped with a 4.3L V6 (LB4 VIN Z or L35 VIN W) engine see Corporate Bulletin 376006 for information on converting from net lash to adjustable lash and/or re-lashing the valves on an adjustable lash system. Investigation of "cold knock" is continuing. Updates will continue to be provided when available. Parts Information Check-Valve Filters Description Part Number V6, V8 (Four-Wheel Drive) FRAM PH3980 12555891 V8 (Two-Wheel Drive), Mark V8 PF1218 25160561 The FRAM PH3980 is to be used in place of the PF52. The PH3980 provides superior anti-drainback performance, a key factor in reducing cold knock. FRAM filters are to be procured locally until 08-15-95. After this date the filters may be ordered from GMSPO using the supplied part number. Orders placed to GMSPO prior to this date will not be placed on backorder. Bearings Description Part Number 0.001" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 10120992 0.001" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 10120994 0.002" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 12329758 0.002" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 12329792 Main bearing kits are currently available from GMSPO. All calibrations are currently available from GMSPO. Page 1673 Distributor: Testing and Inspection INSPECT 1. Distributor cap for cracks or tiny holes. Replace the cap if it is damaged or worn. 2. Metal terminals in the distributor cap for corrosion. Scrape them clean with a knife or replace the cap. 3. Rotor for wear or burning at the outer terminal. The presence of carbon on the terminal indicates rotor wear and the need for replacement. 4. Distributor shaft for shaft-to-bushing looseness. Insert the shaft in the distributor housing. If the shaft wobbles, replace the distributor housing and/or shaft. 5. Distributor housing for cracks or damage. MEASURE Tools Required J 24642-F Module Tester. Electrical performance of the module. The module can only be tested with an approved module tester, such as J 24642-F. Follow the directions that come with the tester. Description and Operation Fuel Pump Signal: Description and Operation PURPOSE The fuel pump voltage signal is a reading of the voltage found at the fuel pump. It is used by the control module as the system voltage. The control module uses fuel pump volts as a reference to determine electrical loading. Page 2941 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3841 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3442 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Locations Instrument Panel Wiring, LH Side Page 1956 campaign bulletin before customers take possession of these vehicles. Dealers are to service all vehicles subject to this campaign at no charge to customers, regardless of mileage, age of vehicle, or ownership, from this time forward. Customers who have recently purchased vehicles sold from your vehicle inventory, and for which there is no customer information indicated on the dealer listing, are to be contacted by the dealer. Arrangements are to be made to make the required correction according to the instructions contained in this bulletin. This could be done by mailing to such customers a copy of the appropriate divisional customer letter accompanying this bulletin. Campaign follow up cards should not be used for this purpose, since the customer may not as yet have received the notification letter. In summary, whenever a vehicle subject to this campaign enters your vehicle inventory, or Is in your dealership for service in the future, please take the steps necessary to be sure the campaign correction has been made before selling or releasing the vehicle. Service Procedure 1. Verify the truck is equipped with General Ameri*550 AS LT225/75R16D tires. (Some trucks may come from the factory with General tires on front, and another brand on the rear. Proceed with service procedure on General Tires only. 2. Mark the orientation of the tire to the wheel. 3. Raise the vehicle on the hoist. Check the sidewalls of the tires including the spare for any bulge, if a bulge is found, that tire will need to be replaced. Whether a bulge is found or not, totally deflate all General Tires. 4. Remove the deflated tire/wheel assemblies from the truck. Dismount the tire from the wheel Carefully inspect the tire bead's for any cuts, tears or other damage (See Figure 2). 5. If no damage is found, remount the tire on the wheel using the orientation marks made in Step # 2 and install the tire/wheel assembly on the truck. Torque wheel to specification. Proceed to step # 7. CAUTION: Over tightening of wheel lugs could distort brake rotors resulting brake pulsation. Use an accurate torque wrench and refer to Section 3E-8 Tires and Wheels of the service manual for proper tightening sequence and torque specifications. 6. If damage is found, replace the tire. Mount & balance new tire & install on truck. Torque wheel to specification by following torque procedure specified in step # 5. 7. Install the GM Campaign Identification Label. Page 1081 HD Electronic 4-Speed Automatic Overdrive Transmission With 4WD Indicator Lamp Remains Illuminated Coolant Level Indicator Lamp: Testing and Inspection Indicator Lamp Remains Illuminated 1. Turn ignition switch to the On position, then check coolant level and add coolant as necessary. If lamp remains illuminated, proceed to step 2. 2. Disconnect electrical connector at the sensor. If lamp does not illuminate replace the sensor. If lamp remains illuminated, proceed to step 3. 3. Connect electrical lead to the sensor and check for an open circuit between the sensor and the module. Repair or replace as necessary. If circuit is satisfactory, replace the ECM. Page 2728 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3743 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3608 A/C Signal: Testing and Inspection A/C Circuit CIRCUIT AND TEST DESCRIPTION Turning "ON" the air conditioning supplies CKT 59 battery voltage to the A/C compressor clutch and to terminal "E12" of the PCM connector to increase and maintain idle speed. The PCM does not control the A/C compressor clutch, therefore, if A/C does not function, refer to A/C diagnosis for diagnosis of the system. If A/C is operating properly and idle speed dips too low when the A/C compressor turns "ON" or flares too high when the A/C compressor turns "OFF," check for an open CKT 59 to the PCM. If circuits are OK, it is a faulty PCM connector terminal "E12" or PCM. Page 3313 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 2942 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1386 Electronic 4-Speed Automatic Overdrive Transmission W/4WD Drivetrain - Slow Or No Engagement of Front Axle Technical Service Bulletin # 76-43-01A Date: 980901 Drivetrain - Slow Or No Engagement of Front Axle File In Section: 4 Drive Axle Bulletin No.: 76-43-01A Date: September, 1998 Subject: Slow or no Engagement of Front Axle when 4WD is selected (Replace Front Axle Actuator) Models: 1988-97 Chevrolet and GMC K Models excluding 1988-93 Models over 8500 # GVW This bulletin is being revised to add information to the Service Procedure, add a new part number, and include schematics. Please discard Corporate Bulletin Number 76-43-01 (Section 4 - Drive Axle). Condition Some owners may comment that the colder the outside temperature is, the longer it takes for the front axle to engage when 4 wheel drive is selected, or the front axle does not engage. Cause The front axle engagement actuator is a thermally activated component. Because of this characteristic, the time required for the actuator to complete 4 wheel drive engagement is extended as the temperature drops. Correction Replace the front axle actuator and include the applicable wiring harness kit. Refer to the Parts Information in order to determine which wiring harness kit is needed. 1996 model trucks with a build date on or after January 2, 1996 are considered as "961". If the build date of the truck is unknown, verify the 3 character "axle code" on the front axle label in order to determine which wire harness to order. This new actuator uses a motor to engage the front axle and is not affected by temperature. On 1988-93 models with a GVW rating over 8500$, the new actuator cannot be installed and the thermal actuator will remain the service part. Parts Information P/N Description Qty 26060073 Actuator Asm, Frt Drive Axle 1 22510339 Fastener 1 15313272 Harness, Jumper (Z Splice) 1 (86-93 K1-3) Parts are currently available from GMSPO. Page 2367 the engine block and intake manifold. See Figures 1 and 2. Wacker T-330 RTV has improved adhesive abilities, is oxygen sensor safe, and is noncorrosive to ferrous metals. Wacker T-330 RW cannot be used in coolant sealing surface areas. Page 2963 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3904 Idle Speed/Throttle Actuator - Mechanical: Description and Operation Purpose: The idle speed control actuator system assists the idle air control system in controlling the idle speed, primarily at cold temperatures. Operation: The idle speed control actuator is a vacuum operated device which opens the throttle slightly (2 to 3 degrees of angle) to increase the cold engine idle speed, to improve the mixing of the air and fuel, and to allow lower warmed up engine idle speeds. The idle speed control actuator is controlled by the idle speed control actuator solenoid, which is controlled by the control module. To increase the idle speed, the solenoid is turned "OFF," and no vacuum is routed to the idle speed control actuator, allowing it to open the throttle slightly. To decrease the idle speed, the solenoid is turned "ON" and vacuum is routed through the solenoid to the idle speed control actuator, allowing the throttle to fully close. In conjunction with the idle speed control actuator system, the idle air control continuously monitors and controls the engine idle speed to the desired idle speed. A Tech 1 scan tool will read the control module commands to the idle speed control actuator system. Page 2830 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3842 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3624 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Number 1 Cylinder Location Page 1556 Page 2332 Auxiliary Engine Oil Cooler Assembly REMOVE OR DISCONNECT - Set the parking brake. 1. Oil cooler lines from the connector. Removing Oil Cooler Line From Connector - Using a small pick-type tool and your thumb (A in image), grasp the connector end and pull the clip from the connector (B in image). This releases the cooler line from the connector. NOTICE: Do not use more than 690 kPa (100 psi) air to clean the cooler and lines. Exceeding 690 kPa (100 psi) could damage the cooler or lines. A. Using clean solvent and compressed air, back-flush the oil cooler and lines. B. Using compressed air, remove the cleaning solvent. C. Flush the system using the same type of oil normally circulated through the cooler. 2. Bolt or nut from bracket or clamp. 3. Oil filter and discard. 4. Oil cooler lines from the clip or strap. 5. Oil cooler lines from the oil cooler at fitting. CLEAN - All components in a suitable solvent and dry with compressed air. Page 790 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Starting - Revised Procedures for Inop Ignition Cylinder Technical Service Bulletin # 73-01-09 Date: 971001 Starting - Revised Procedures for Inop Ignition Cylinder File In Section: 0 - General Information Bulletin No.: 73-01-09 Date: October, 1997 INFORMATION Subject: New Tumblers for Cylinder Recoding, Revised Repair Procedures for Inoperative Ignition Cylinders (Seized/Won't Rotate), Labor Operation/Time Allowances Models: 1995-97 Buick Skylark, Riviera 1995-97 Chevrolet Cavalier 1997 Chevrolet Corvette, Malibu, Venture 1995-97 Oldsmobile Achieva 1997 Oldsmobile Aurora, Cutlass, Silhouette 1995-97 Pontiac Grand Am, Sunfire 1997 Pontiac Grand Prix, Trans Sport 1995-97 Chevrolet and GMC C/K, S/T Models 1996-97 Chevrolet and GMC G, M/L Vans 1996-97 Oldsmobile Bravada The information in this bulletin concerns new designed tumblers for recoding lock cylinders that use double sided reversible keys, revised procedures for servicing ignition lock cylinders that are seized or not able to rotate and revised labor time guide information and allowances. Parts Information Parts are currently available from GMSPO. Warranty Information Specifications Temperature Vs Resistance Value Page 1372 4. Locate the surface for the cylinder release button on the plastic ignition switch housing and center punch a location on the "rib" approximately 3/8" rearward (toward the key entry end) from the cylinder release button, see Figure 3. 5. Using a 1/8" drill bit, carefully drill a pilot hole through the plastic housing only. 6. Using a 9/32" drill bit, carefully drill a larger hole at the pilot location, and slightly into the lock cylinder surface to break the release button retaining spring. 7. Remove portions of the broken spring from the hole using a small pair of needle nose pliers (or other suitable tool) and turn switch over to shake out the release button. 8. Grasp the lock cylinder, remove it from the switch housing. 9. Remove any plastic "flash" from the drilling operations and, using compressed air, blow out the ignition switch assembly. 10. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 11. Install the new cylinder(s) as required by rotating both the cylinder and ignition switch to the "ON" position and pushing the cylinder into the switch. It may be necessary to depress the release button slightly as it passes by the 9/32" hole previously drilled in the housing. 12. Reassemble the ignition switch and instrument panel components as indicated by the appropriate Service Manual. Page 3903 Idle Speed Control Actuator System Page 371 13. Using template (Figure 5), mark cutting lines on the lower evaporator case using a china marker or equivalent (Figure 1). 14. Cut through the plastic upper evaporator case and the lower evaporator case following the marked outlines of the templates to create two access doors (Figure 1). Do not cut rear edge of either access door (Figure 4 and 5). Use a hot knife or a small (1/2" dia.) rotary abrasive cutting wheel. Page 3211 Fig.2-Symbols (Part 2 Of 3) Page 2832 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3040 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 1517 Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 2395 Oil Pressure Switch (For Fuel Pump): Service and Repair Oil Pressure Switch REMOVE OR DISCONNECT 1. Electrical connector. 2. Oil pressure switch using wrench J 35748. INSTALL OR CONNECT 1. Oil pressure switch. 2. Electrical connector. Page 3625 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3152 1994 G VAN 3A-7O Page 79 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 242 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1772 Notice: Cut through plastic case material only. Aluminum tubes are located approximately 1/8" behind the case wall (Figure 2, view 1). Do not use a larger diameter cutting wheel. 15. Using a heat gun to soften the plastic case, pull back the access door on the upper evaporator case carefully to prevent breaking the case. Reach in carefully and remove the holding clamp securing the capillary tube to the evaporator outlet tube. Be careful not to damage the capillary tube. Discard clamp. 16. Using a heat gun to soften the plastic case, pull back the access door on the lower evaporator case carefully to prevent breaking the case (Figure 2). Reach in carefully with two small adjustable wrenches and loosen the fitting attaching the TXV to the evaporator inlet tube. It will require a 7/8" crows foot extension to loosen the TXV outlet joint fitting hidden behind the TXV itself. Remove and discard the TXV. 17. Remove original O-rings from the evaporator tubes and replace with new O-rings that have been oiled with 525 viscosity refrigerant mineral oil. DO NOT USE PAG LUBRICANT. 18. Install the new TXV to the evaporator tubes being careful not to damage the O-rings. Finger tighten the joints and then torque the joints, using a backup wrench to hold the TXV in position to: INLET 20-35 Nm (14-25 lb.ft.) OUTLET 15-22 Nm (11-16 lb.ft.) Locations Headlamp Dimmer Switch: Locations Part of the multifunction switch. Page 3396 Fig.1-Symbols (Part 1 Of 3) Page 1235 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3080 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3824 Engine Control Module: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 804 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3823 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 2538 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 28 - HVAC Actuator - Inflatable Restraint Sensing and Diagnostic Module (SDM) - Any AIR BAG module - Seatbelt Lap Anchor Pretensioner - Seatbelt Retractor Pretensioner - An SIR system connection or connector condition resulting in the following DTCs being set: B0015, B0016, B0019, B0020, B0022, or B0023 - Powertrain Control Module (PCM) - Remote Control Door Lock Receiver (RCDLR) - Transmission Control Module (TCM) Correction Important DO NOT replace the control module, wiring or component for the following conditions: - The condition is intermittent and cannot be duplicated. - The condition is present and by disconnecting and reconnecting the connector the condition can no longer be duplicated. Use the following procedure to correct the conditions listed above. 1. Install a scan tool and perform the Diagnostic System Check - Vehicle. Retrieve and record any existing history or current DTCs from all of the control modules (refer to SI). ‹› If any DTC(s) are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle to identify the connector(s) of the control module/component which may be causing the condition (refer to SI). ‹› If DTCs are not set, refer to Symptoms - Vehicle to identify the connector(s) of the control module/component which may be causing the condition (refer to SI). 2. When identified, use the appropriate DTC Diagnostics, Symptoms, Schematics, Component Connector End Views and Component Locator documents to locate and disconnect the affected harness connector(s) which are causing the condition. Note Fretting corrosion looks like little dark smudges on electrical terminals and appear where the actual electrical contact is being made. In less severe cases it may be unable to be seen or identified without the use of a magnifying glass. Important DO NOT apply an excessive amount of dielectric lubricant to the connectors as shown, as hydrolock may result when attempting to mate the connectors. Use ONLY a clean nylon brush that is dedicated to the repair of the conditions in this bulletin. 3. With a one-inch nylon bristle brush, apply dielectric lubricant to both the module/component side and the harness side of the affected connector(s). 4. Reconnect the affected connector(s) and wipe away any excess lubricant that may be present. 5. Attempt to duplicate the condition by using the following information: - DTC Diagnostic Procedure - Circuit/System Description - Conditions for Running the DTC - Conditions for Setting the DTC - Diagnostic Aids - Circuit/System Verification ‹› If the condition cannot be duplicated, the repair is complete. ‹› If the condition can be duplicated, then follow the appropriate DTC, Symptom or Circuit/System Testing procedure (refer to SI). Repair Order Documentation Page 872 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3332 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 444 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 239 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3724 Coolant Temperature Sensor/Switch (For Computer): Description and Operation Engine Coolant Temperature (ECT) Sensor PURPOSE The Engine Coolant Temperature (ECT) sensor is a thermistor (a resistor which changes value based on temperature) mounted in the engine coolant stream. Low coolant temperature produces a high resistance (100,000 ohms at -40° C (-40° F) while high temperature causes low resistance (70 ohms at 130° C (266° F). OPERATION The control module supplies a 5 volt signal to the ECT sensor through a resistor in the control module and measures the voltage. The voltage will be high when the engine is cold, and low when the engine is hot. Engine coolant temperature affects most systems controlled by the control module. Page 213 Engine Control Module: Service and Repair Fuel Module (Located Above Blower Motor Assembly) Replacement of the Powertrain Control Module (PCM) consists of a service controller, without a PROM (MEM-CAL). If the diagnostic procedures require the PCM to be replaced, the PCM, PROM (MEM-CAL) should be checked for the correct part number. If they are correct, remove the PROM (MEM-CAL), and install them in the control module. The control module will not contain a PROM (MEM-CAL). IMPORTANT: When replacing a production PCM with a control module, transfer the broadcast code and production PCM part number to the control module label. Do not record information on the access cover. NOTE: The ignition must be "OFF," and disconnect negative battery cable when disconnecting or reconnecting the PCM connector, to prevent internal damage to the PCM. NOTE: To prevent possible Electrostatic Discharge damage to the PCM, Do Not touch the connector pins or soldered components on the circuit board. REMOVE OR DISCONNECT 1. Negative battery cable. 2. Glove box. 3. PCM harness connectors. 4. PCM from tray. 5. Mounting brackets and modules if equipped. 6. Access cover PROM (MEM-CAL). INSTALL OR CONNECT 1. PROM (MEM-CAL) access cover in new PCM. 2. Mounting brackets and modules if equipped. 3. PCM into tray until clips lock. 4. PCM harness connectors. 5. Glove box. 6. Negative battery cable. 7. Perform functional check. Page 788 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 2959 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2031 Do not use cleaning solutions that contain hydrofluoric, oxalic and most other acids on chrome wheels (or any wheels). If the customer is unsure of the chemical make-up of a particular wheel cleaner, it should be avoided. For wheels showing signs of milky staining from acidic cleaners, refer to Customer Assistance and Instructions below. Warranty of Stained Chrome Wheels Stained wheels are not warrantable. Most acid based cleaners will permanently stain chrome wheels. Follow-up with dealers has confirmed that such cleaners were used on wheels that were returned to the Warranty Parts Center (WPC). Any stained wheels received by the WPC will be charged back to the dealership. To assist the customer, refer to Customer Assistance and Instructions below. Pitting or Spotted Appearance of Chrome Wheels Figure 2 A second type or staining or finish disturbance may result from road chemicals, such as calcium chloride used for dust control of unpaved roads. The staining will look like small pitting (refer to Figure 2). This staining will usually be on the leading edges of each wheel spoke, but may be uniformly distributed. If a vehicle must be operated under such conditions, the chrome wheels should be washed with mild soap and water and thoroughly rinsed as soon as conveniently possible. Important Road chemicals, such as calcium chloride used for dust control of unpaved roads, can also stain chrome wheels. The staining will look like small pitting. This staining will usually be on the leading edges of each wheel spoke. This is explained by the vehicle traveling in the forward direction while being splashed by the road chemical. If a vehicle must be operated under such conditions, the chrome wheels should be washed with mild soap and water and thoroughly rinsed as soon as conveniently possible. Warranty of Pitted or Spotted Chrome Wheels Wheels returned with pitting or spotting as a result of road chemicals may be replaced one time. Damage resulting from contact with these applied road chemicals is corrosive to the wheels finish and may cause damage if the wheels are not kept clean. Important Notify the customer that this is a one time replacement. Please stress to the customer the vital importance of keeping the wheels clean if they are operating the vehicle in an area that applies calcium chloride or other dust controlling chemicals! "GM of Canada" dealers require prior approval by the District Manager - Customer Care and Service Process (DM-CCSP). "Stardust" Corrosion of Chrome Wheels Figure 3 A third type of finish disturbance results from prolonged exposure to brake dust and resultant penetration of brake dust through the chrome. As brakes are applied hot particles of brake material are thrown off and tend to be forced through the leading edge of the wheel spoke windows by airflow. These Locations Fuel Pump Relay: Locations FUEL PUMP RELAY Underhood Fuse/Relay Center The Fuel Pump Relay is located in Underhood Fuse Relay Center. The Underhood Fuse Relay Center is located on the LH rear of engine compartment, on fender. Locations Convenience Center Page 3018 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1998 1. The tire must be in the relaxed position when the repair unit is installed (Do not spread the beads excessively). Two-Piece Plug and Repair Units 1. If applicable, install the repair unit so that the alignment is correct. 2. Center the repair unit over the injury and stitch down thoroughly with the stitching tool, working from the center out. 3. Being careful not to stretch the plug material, cut the plug flush with the outer tread. Combination Repair/Plug Units 1. Pull the plug through the injury until the repair just reaches the liner. Stitch down thoroughly. 2. Follow the repair material manufacturer's recommendations for further installation instructions. 2. Consult your repair material supplier for the proper stitching tool. Safety Cage Page 3962 Knock Sensor: Service and Repair REMOVE OR DISCONNECT 1. Negative battery cable. 2. Drain cooling system. NOTE: On knock sensors which are mounted in the end of the cylinder head draining the cooling system will not be necessary. 3. Wiring harness connector from knock sensor. 4. Knock sensor from cylinder head or block. INSTALL OR CONNECT 1. Knock sensor into cylinder head or block. Apply water base caulk to sensor threads. Do not use silicon tape as this will insulate sensor from engine block. Tighten to 19 Nm (14 lb. ft.). 2. Wiring harness connector to the knock sensor. 3. Negative battery cable. 4. Refill cooling system if required. Locations Engine Page 2529 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Diagram Information and Instructions Fluid Pressure Sensor/Switch: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 1179 Fig.2-Symbols (Part 2 Of 3) Page 1680 Spark Plug: Description and Operation DESCRIPTION Resistor-type, tapered-seat spark plugs are used on this engine. No gasket is used on these spark plugs. Application and ID explains the letter coding on these spark plugs. A dot before the spark plug code or the letter "C" after the number in the code indicates the spark plug has a copper core. Refer to Specification / Mechanical or to the vehicle emissions control information label for correct gap information. CONSTRUCTION These spark plugs have a ceramic insulator that is approximately 6.35 mm (1/8 inch) longer than conventional spark plugs. The longer length spark plugs magnify the problem of cracked insulators because most spark plug sockets are not of sufficient length to properly engage the shell hex. If the spark plug shell hex is not fully engaged in the spark plug socket wrench, the socket may cause insulator cracking and/or breakage during plug installation or removal. OPERATION When servicing these spark plugs, make sure the spark plug socket being used is deep enough to accommodate the longer length insulator. Use of a spark plug socket that is NOT deep enough may result in the ceramic insulator becoming cracked above the spark plug shell. Normal or average service is assumed to be a mixture of idling, low speed, and high speed operation with some of each making up the total daily driving. Occasional or intermittent high-speed driving is essential to good spark plug performance. It provides increased and sustained combustion heat that burns away excess deposits of carbon or oxide that may have accumulated from frequent idling or continual stop-and-go or slow-speed driving. Spark plugs are protected by an insulating boot made of special heat-resistant material that covers the spark plug terminal and extends downward over a portion of the plug insulation These boots prevent flash-over with resultant missing of the engine. Do not mistake corona discharge for flash-over or a shorted insulator. Corona discharge is a steady blue light appearing around the insulator, just above the shell crimp. It is the visible evidence of a high-tension field and has no effect on ignition performance. Usually it can be detected only in darkness. This discharge may repel dust particles, leaving a clear ring on the insulator just above the shell. This ring is sometimes mistakenly regarded as evidence that combustion gases have blown out between the shell and insulator. Page 1339 Knock Sensor Circuit Page 3586 Distributor: Service and Repair Distributor Replacement Preassembled replacement distributors are not available. Components are available to assemble a new distributor. Some components, such as the air cleaner, may need to be removed to reach the distributor. The distributor has a separate ignition coil that mounts to a bracket on the top of the engine. REMOVE OR DISCONNECT Make sure the ignition switch is "OFF." 1. Air cleaner and hoses. 2. Electrical connectors at the side of the distributor cap. 3. Two screws on the sides of the distributor cap. 4. Ignition coil wire and spark plug wires on either the left or right side of the distributor. 5. Distributor cap and move it aside. A. Use chalk to note the position of the rotor in relation to the engine. B. Use chalk to note the position of the distributor housing in relation to the engine. 6. Distributor bolt and hold-down clamp. 7. Distributor. INSTALL OR CONNECT 1. Distributor. A. To ensure correct timing of the distributor, it must be installed with the rotor correctly positioned as noted in step 5 of the removal procedure. Line up the rotor to the mark on the engine, and the mark on the housing to the engine. B. If the distributor shaft won't drop into the engine, remove the distributor, insert a screwdriver into the hole for the distributor and rotate the oil pump driveshaft so it lines up with the distributor drive gear. 2. Hold-down clamp and bolt. Tighten Bolt to 27 Nm (20 lbs. in.). 3. Distributor cap with two screws. 4. Wiring harness connectors to the sealed ICM connectors at the side of the distributor. 5. Spark plug wires and coil wire. 6. Air cleaner and hoses. Check the ignition base timing. Number 1 Cylinder Location Page 3188 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 1412 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3503 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 2625 Temp Sensor Circuit Wiring Page 3896 Idle Air Control Valve: Testing and Inspection IAC Check Page 3495 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 665 Brake Light Switch: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 490 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 2038 longer. Important Whenever a wheel is refinished, the mounting surface and the wheel nut contact surfaces must not be painted or clearcoated. Coating these surfaces could affect the wheel nut torque. When re-mounting a tire on an aluminum wheel, coated balance weights must be used in order to reduce the chance of future cosmetic damage. Disclaimer Page 3897 IAC Circuit CIRCUIT DESCRIPTION The control module controls engine idle speed with the IAC valve. To increase idle speed, the control module retracts the IAC valve pintle away from it's seat, allowing more air to pass by the throttle bore. To decrease idle speed, it extends the IAC valve pintle towards it's seat, reducing bypass air flow. A Tech 1 scan tool will read the control module commands to the IAC valve in counts. Higher the counts indicate more air bypass (higher idle). The lower the counts indicate less air is allowed to bypass (lower idle). CHART TEST DESCRIPTION Number(s) below refer to circled number(s) on the diagnostic chart. 1. The IAC tester is used to extend and retract the IAC valve. Valve movement is verified by an engine speed change. If no change in engine speed occurs, the valve can be retested when removed from the throttle body. 2. This step checks the quality of the IAC movement in Step 1. Between 700 rpm and about 1500 rpm the engine speed should change smoothly with each flash of the tester light in both extend and retract. If the IAC valve is retracted beyond the control range (about 1500 rpm), it may take many flashes in the extend position before engine speed will begin to drop. This is normal on certain engines, fully extending IAC may cause engine stall. This may be normal. 3. Steps 1 and 2 verified proper IAC valve operation while this step checks the IAC circuits. Each lamp on the node light should flash red and green while the IAC valve is cycled. While the sequence of color is not important if either light is "OFF" or does not flash red and green, check the circuits for faults beginning with poor terminal contacts. IAC VALVE RESET PROCEDURE ^ Disconnect battery cable at battery for 10 seconds then reconnect cable. ^ Ignition "ON," engine "OFF" for 5 seconds. ^ Ignition "OFF" for 10 seconds. DIAGNOSTIC AIDS A slow, unstable, or fast idle may be caused by a non-IAC system problem that cannot be overcome by the IAC valve. Out of control range, IAC Tech 1 scan tool counts will be above 60 if idle is too low, and zero counts if idle is too high. The following checks should be made to repair a non-IAC system problem. ^ VACUUM LEAK (High Idle) - If idle is too high, stop the engine. Fully extend (low) IAC with tester. Start engine. If idle speed is above 800 rpm, locate and correct vacuum leak including crankcase ventilation system. Also, check for binding of throttle blade or linkage. ^ SYSTEM TOO RICH (Low Air/Fuel Ratio) - The idle speed will be too low. Tech 1 scan tool IAC counts will usually be above 80. System is obviously rich and may exhibit black smoke in exhaust. Tech 1 scan tool O2 voltage will be fixed above 800 mV (0.8 volt). Check for high fuel pressure, leaking or sticking injector. Silicone contaminated O2S scan voltage will be slow to respond. ^ THROTTLE BODY - Remove IAC valve and inspect bore for foreign material. ^ IAC VALVE ELECTRICAL CONNECTIONS - IAC valve connections should be carefully checked for proper contact. ^ CRANKCASE VENTILATION VALVE - An incorrect or faulty crankcase ventilation valve may result in an incorrect idle speed. Refer to Diagnosis By Symptom / Rough, Unstable Or Incorrect Idle, Stalling. ^ A/C COMPRESSOR - Refer to A/C diagnosis if circuit is shorted to ground. If the relay is faulty, an idle problem may exist. Refer to Diagnosis By Symptom / Rough, Unstable Or Incorrect Idle, Stalling. ^ If intermittent poor driveablity or idle symptoms are resolved by disconnecting the IAC, carefully recheck connections, valve terminal resistance or replace IAC. Page 3449 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 559 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Compressor Pressure Switch Refrigerant Pressure Sensor / Switch: Service and Repair Compressor Pressure Switch Compressor Pressure Switch Remove or Disconnect 1. Negative battery cable. 2. Electrical connectors, as necessary. 3. Compressor pressure switch. 4. O-Ring seal. Install or Connect 1. New O-ring seal. - Coat O-ring seal with 525 viscosity refrigerant oil. 2. Compressor pressure switch. Tighten Compressor pressure switch to 6 Nm (53 lb in.). 3. Electrical connectors, as necessary. 4. Negative battery cable. Page 198 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 1317 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 3663 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 830 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1137 Air Flow Meter/Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 434 Fig.1-Symbols (Part 1 Of 3) Page 1185 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 180 Fig.1-Symbols (Part 1 Of 3) Page 2722 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3288 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 3413 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 483 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3869 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2735 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3769 Fig.2-Symbols (Part 2 Of 3) Page 3894 Idle Air Control Valve: Electrical Diagrams ISC Actuator Circuit IAC Circuit Page 1780 Page 938 Manifold Absolute Pressure (MAP) Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 441 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1270 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Page 294 Specifications Radiator Cap: Specifications Radiator Cap Relief Pressure, Lbs. ..................................................................................................... ............................................................................... 15 Thermo. Opening Temp., deg.F ..................... .............................................................................................................................................................. .... 195 Page 1033 Fig.2-Symbols (Part 2 Of 3) Page 3339 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 450 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 3577 Spark Plug Wire: Service and Repair SERVICE CAUTIONS 1. Twist boots one-half turn before removing. 2. When removing the boot, do not use pliers or other tools that could tear the boot. 3. Do not force anything between the wire and the boot, or through the silicone jacket of the wiring. 4. Do not pull on the wires to remove the boot. Pull on the boot or use a tool designed for this purpose. 5. Special care should be used when installing spark plug boots to ensure the metal terminal within the boot is fully seated on the spark plug terminal and the boot has not moved on the wire. SPARK PLUG WIRE REPLACEMENT Spark plug wire routings must be kept intact during service and followed exactly when spark plug wires have been disconnected or when replacement of the spark plug wires is necessary. Failure to route the spark plug wires properly can lead to radio noise and crossfiring of the spark Page 3407 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3774 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 408 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 842 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 3320 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3954 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 560 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 3096 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1224 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 519 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Front Wheel Driveshaft Boot - Damage Prevention Constant Velocity Joint Boot: All Technical Service Bulletins Front Wheel Driveshaft Boot - Damage Prevention File In Section: 4 - Drive Axle Bulletin No. 56-43-01 Date: March, 1995 Subject: Preventing Front Wheel Driveshaft Boot Damage Models: 1995 and Prior Light Duty Trucks with Four Wheel Drive (4WD) or All Wheel Drive (AWD) When diagnosing a vehicle for customer concerns such as noise and/or vibrations, it is often necessary to run the vehicle while it is supported in the air by hoists or jack stands. On light duty truck models with four wheel drive (4WD) or All Wheel Drive (AWD) the front suspension should not be allowed to hang free while performing on-hoist testing. It the front suspension is allowed to hang free, the CV joint will be at a very high angle. This will likely result in damage to the front wheel driveshaft boots. In addition, extra vibrations may occur and may damage the front wheel driveshaft joints. When on-hoist testing an AWD or 4WD light duty truck, support the outer end of the lower control arm using jack stands. This will reduce the CV joint angle and prevent damage to the front wheel driveshaft assembly. Page 2850 Engine Control Module: Connector Views Engine Controls - Throttle Body Injection: C1 Pinout Description: C1 (Part 1 Of 2) Page 979 Oxygen Sensor: Technical Service Bulletins Oxygen Sensors - Silica Contamination Model Year: 1981 Bulletin No: 81-I-37 File In Group: 60 Number: 11 Date: Feb. 81 Subject: Silica Contamination of Oxygen Sensors and Gelation of Oil. Models Affected: All Oxygen sensor performance can deteriorate if certain RTV silicone gasket materials are used. Other RTV's when used with certain oils, may cause gelation of the oil. The degree of performance severity depends on the type of RTV and application of the engine involved. Therefore, when repairing engines where this item is involved, it is important to use either cork composition gaskets or RTV silicone gasket material approved for such use. GMS (General Motors Sealant) or equivalent material can be used. GMS is available through GMPD with the following part numbers: 1052366 3 oz. 1052434 10.14 oz. Page 3722 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 1597 A wheel alignment will generally NOT correct vehicles that follow the road crown since this is within "Normal Operation." Mileage Policy The following mileage policy applies for E2020 and E2000 labor operations: Note Wheel Alignment is NOT covered under the New Vehicle Limited Warranty for Express and Savana Cutaway vehicles as these vehicles require Upfitters to set the wheel alignment after completing the vehicles. - 0-800 km (0-500 mi): E2000/E2020 claims ONLY allowed with Call Center Authorization. Due to the tie down during shipping, the vehicle's suspension requires some time to reach normal operating position. For this reason, new vehicles are generally NOT to be aligned until they have accumulated at least 800 km (500 mi). A field product report should accompany any claim within this mileage range. - 801-12,000 km (501-7,500 mi): - If a vehicle came from the factory with incorrect alignment settings, any resulting off-angle steering wheel, lead/pull characteristics or the rare occurrence of excessive tire wear would be apparent early in the life of the vehicle. The following policy applies: - Vehicles 100% Factory Set/Measured for Caster/Camber/Toe - Escalade/ESV/EXT, Tahoe/Suburban, Yukon/XL/Denali, Silverado/Sierra, Express/Savana, Corvette and Colorado/Canyon: E2000/E2020 Claims: Call Center Authorization Required - All Vehicles NOT 100% Factory Set/Measured for Caster/Camber/Toe as noted above: E2000/E2020 Claims: Dealer Service Manager Authorization Required - 12,001 km and beyond (7,501 miles and beyond): During this period, customers are responsible for the wheel alignment expense or dealers may provide on a case-by case basis a one-time customer enthusiasm claim up to 16,000 km (10,000 mi). In the event that a defective component required the use of the subject labor operations, the identified defective component labor operation will include the appropriate labor time for a wheel alignment as an add condition to the component repair. Important Only one wheel alignment labor operation claim (E2000 or E2020) may be used per VIN. Warranty Documentation Requirements When a wheel alignment service has been deemed necessary, the following items will need to be clearly documented on/with the repair order: - Customer concern in detail - What corrected the customer concern? - If a wheel alignment is performed: - Consult SI for proper specifications. - Document the "Before" AND "After" wheel alignment measurements/settings. - Completed "Wheel Alignment Repair Order Questionnaire" (form attached to this bulletin) 1. Document the customer concern in as much detail as possible on the repair order and in the warranty administration system. Preferred examples: - Steering wheel is off angle in the counterclockwise direction by approximately x degrees or clocking position. - Vehicle lead/pulls to the right at approximately x-y mph. Vehicle will climb the road crown. Severe, Moderate or Slight. - RF and LF tires are wearing on the outside shoulders with severe feathering. Important In the event of a lead/pull or steering wheel angle concern, please note the direction of lead/pull (left or right) or direction of steering wheel angle (clockwise or counterclockwise) on the repair order and within the warranty claim verbatim. Important In the event of a tire wear concern, please note the position on the vehicle and where the wear is occurring on the tire; i.e., the RF tire is wearing on the inside shoulder. 2. Document the technician's findings on cause and correction of the issue. Examples: - Reset LF toe from 0.45 degrees to 0.10 degrees and RF toe from -0.25 degrees to 0.10 degrees to correct the steering wheel angle from 5 degrees counterclockwise to 0 degrees. - Reset LF camber from 0.25 degrees to -0.05 degrees to correct the cross-camber condition of +0.30 degrees to 0.00 degrees on the vehicle. - Front Sum toe was found to be 0.50 degrees, reset to 0.20 degrees. 3. Print-out the "Before" and "After" wheel alignment measurements/settings and attach them to the Repair Order or if print-out capability is not Page 3000 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Compressor Pressure Switch Refrigerant Pressure Sensor / Switch: Description and Operation Compressor Pressure Switch PURPOSE This system is equipped with a compressor pressure switch that is normally open. It activates at 2069-2482 kPa (300-360 psi) and releases at 1724 kPa (250 psi). Its function is to drive the recirculation door to the closed position to reduce the system load and decrease system high-side pressure. Page 1446 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 1080 HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 3720 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 2245 Drive Belt: Technical Service Bulletins Engine - Serpentine Drive Belt Wear Information Bulletin No.: 04-06-01-013 Date: April 29, 2004 INFORMATION Subject: Information on Serpentine Belt Wear Models: 2004 and Prior Passenger Cars and Trucks 2003-2004 and Prior HUMMER H2 All current GM vehicles designed and manufactured in North America were assembled with serpentine belts that are made with an EPDM material and should last the life of the vehicle. It is extremely rare to observe any cracks in EPDM belts and it is not expected that they will require maintenance before 10 years or 240,000 km (150,000 mi) of use. Older style belts, which were manufactured with a chloroprene compound, may exhibit cracks depending on age. However, the onset of cracking typically signals that the belt is only about halfway through its usable life. A good rule of thumb for chloroprene-based belts is that if cracks are observed 3 mm (1/8 in) apart, ALL AROUND THE BELT, the belt may be reaching the end of its serviceable life and should be considered a candidate for changing. Small cracks spaced at greater intervals should not be considered as indicative that the belt needs changing. Any belt that exhibits chunking should be replaced. Disclaimer Page 3510 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1911 Underhood Fuse - Relay Center Page 1207 TP Sensor Circuit Page 1157 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 3940 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 3718 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 1332 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3881 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 2032 hot particles embed themselves in the chrome layer and create a small pit. If the material is allowed to sit on the wheel while it is exposed to moisture or salt, it will corrode the wheel beneath the chrome leaving a pit or small blister in the chrome. Heavy brake dust build-up should be removed from wheels by using GM Chrome Cleaner and Polish, P/N 1050173 (in Canada use 10953013). For moderate cleaning, light brake dust build-up or water spots use GM Swirl Remover Polish, P/N 12377965 (in Canada, use Meguiars Plast-X(TM) Clear Plastic Cleaner and Polish #G12310C**). After cleaning, the wheel should be waxed using GM Cleaner Wax, P/N 12377966 (in Canada, use Meguiars Cleaner Wax #M0616C**), which will help protect the wheel from brake dust and reduce adhesion of any brake dust that gets on the wheel surface. For general maintenance cleaning, PEEK Metal Polish† may be used. It will clean and shine the chrome and leave behind a wax coating that may help protect the finish. Warranty of Stardust Corroded Chrome Wheels Wheels returned with pitting or spotting as a result of neglect and brake dust build-up may be replaced one time. Important Notify the customer that this is a one time replacement. Please stress to the customer the vital importance of keeping the wheels clean and free of prolonged exposure to brake dust build-up. "GM of Canada" dealers require prior approval by the District Manager - Customer Care and Service Process (DM-CCSP). Customer Assistance and Instructions GM has looked for ways customers may improve the appearance of wheels damaged by acidic cleaners. The following product and procedure has been found to dramatically improve the appearance of stained wheels. For wheels that have milky stains caused by acidic cleaners try the following: Notice THE 3M CHROME AND METAL POLISH REQUIRED FOR THIS PROCEDURE IS AN EXTREMELY AGGRESSIVE POLISH/CLEANER. THE WHEELS MUST BE CLEANED BEFORE APPLICATION TO AVOID SCRATCHING THE WHEEL SURFACE. THIS PRODUCT WILL REDUCE THE THICKNESS OF THE CHROME PLATING ON THE WHEEL AND IF USED INCORRECTLY OR EXCESSIVELY MAY REMOVE THE CHROME PLATING ALL TOGETHER, EXPOSING A LESS BRIGHT AND BRASSY COLORED SUB-LAYER. FOLLOW INSTRUCTIONS EXACTLY. 1. Wash the wheels with vigorously with soap and water. This step will clean and may reduce wheel staining. Flood all areas of the wheel with water to rinse. 2. Dry the wheels completely. Notice Begin with a small section of the wheel and with light pressure buff off polish and examine results. ONLY apply and rub with sufficient force and time to remove enough staining that you are satisfied with the results. Some wheels may be stained to the extent that you may only achieve a 50% improvement while others may be able to be restored to the original lustre. IN ALL CASES, only apply until the results are satisfactory. 3. Apply 3M Chrome and Metal Polish #39527* with a clean terry cloth towel. As you apply the polish, the staining will be diminished. 4. When dry, buff off the polish with a clean portion of the towel. 5. Repeat application of the 3M Chrome and Metal Polish until satisfied with the results. If continued applications fail to improve the appearance further discontinue use. This procedure will improve the appearance of the wheels and may, with repeated applications, restore the finish dramatically. For wheels that exhibit spotting from road chemicals the above procedure may marginally improve the condition but will not restore the finish or remove the pitting. In this type of staining the wheel finish has actually been removed in spots and no manner of cleaning will restore the finish. †*We believe this source and their products to be reliable. There may be additional manufacturers of such products/materials. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or material from this firm or for any such items that may be available from other sources. Parts Information Locations Engine Page 985 Oxygen Sensor: Connector Locations HD Electronic 4-Speed Automatic Overdrive Transmission W/4WD Page 2294 Warranty Information Page 201 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3175 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 762 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3789 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 400 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Indicator Lamp Remains Illuminated Coolant Level Indicator Lamp: Testing and Inspection Indicator Lamp Remains Illuminated 1. Turn ignition switch to the On position, then check coolant level and add coolant as necessary. If lamp remains illuminated, proceed to step 2. 2. Disconnect electrical connector at the sensor. If lamp does not illuminate replace the sensor. If lamp remains illuminated, proceed to step 3. 3. Connect electrical lead to the sensor and check for an open circuit between the sensor and the module. Repair or replace as necessary. If circuit is satisfactory, replace the ECM. Page 3635 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 3508 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 3323 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 2760 Thermostat: Service and Repair 1. Drain cooling system until radiator coolant level is below thermostat. 2. Remove thermostat housing bolts and/or studs, then the thermostat housing and thermostat. 3. Thoroughly clean gasket surfaces of thermostat housing and intake manifold. 4. Reverse procedure to install, noting the following: a. Torque bolts to 27 ft. lbs. Locations Keyless Entry Module: Locations Control Module Located in left hand instrument panel sound insulator. A/T - Intermittent Downshift/Slip/Cycling Diagnosis Fan Clutch: Technical Service Bulletins A/T - Intermittent Downshift/Slip/Cycling Diagnosis File In Section: 07 Transmission/Transaxle Bulletin No.: 99-07-30-016B Date: October, 2002 INFORMATION Subject: Diagnostic Information For Intermittent Transmission Downshift, Slip, Busy/cycling TCC or Noisy Cooling Fan Models: 1999-2000 Cadillac Escalade 2002-2003 Cadillac Escalade, Escalade EXT 1988-2003 Chevrolet Astro, Blazer, S-10, Silverado, Suburban 1989-2003 Chevrolet/Geo Tracker 1995-2003 Chevrolet Tahoe 1996-2003 Chevrolet Express 1988-1994 GMC S-15 1988-1999 GMC Suburban 1988-2003 GMC Safari, Sierra 1995-2003 GMC Sonoma, Yukon, Yukon XL 1996-2003 GMC Savana 1999-2001 GMC Envoy 1991-2001 Oldsmobile Bravada 2003 HUMMER H2 with Air Conditioning This bulletin is being revised to change the Model information and text. Please discard Corporate Bulletin Number 99-07-30-016A (Section 07 - Transmission/Transaxle) Some customers may comment that at times the transmission seems to slip, or that there is a loud roar from the engine with slow acceleration. This condition is most noticeable after the vehicle has sat idle for 12 or more hours, or on hot days when the A/C is on and the vehicle moves slowly with traffic. Typical comments from customers may include the following conditions: ^ Intermittent slipping ^ Intermittent downshift followed by an upshift, both with no apparent reason ^ Busyness or cycling of the TCC (torque converter clutch) at steady throttle conditions and on a level roadway ^ Noisy cooling fan The type of concern described above requires further definition. The customer should be asked the following questions: ^ Is the situation more pronounced with higher vehicle loads such as when pulling a trailer? ^ Do warmer ambient temperatures make the situation more pronounced? ^ When the condition occurred, did you have the A/C on, and were you driving in stop and go city traffic? ^ Does the condition exhibit itself on the first start-up after sitting more than eight hours? If the customer indicates that these conditions apply, and your observation confirms that the vehicle is operating properly, provide the customer with the vehicle operating description included at the end of this bulletin. Further action may not be necessary. A service procedure follows if further definition is required. Diagnostic Aids Cooling fan operation or the resulting sound varies. The cooling fan clutch may be described as a continuously variable clutch. If the vehicle engine is running, the fan blade is always turning unless the fan clutch is non-functional. The speed of the fan in relation to engine speed is temperature dependent. Crankshaft Balancer - Removal/Installation Tool Harmonic Balancer - Crankshaft Pulley: Technical Service Bulletins Crankshaft Balancer Removal/Installation Tool File In Section: 6 - Engine Bulletin No.: 57-61-38 Date: January, 1996 SERVICE MANUAL UPDATE Subject: Section 6A - Engine Mechanical - Crankshaft Balancer Remover/Installer Tool Incorrectly Referenced Models: 1990-96 Chevrolet and GMC Truck S/T; M/L, C/K, P, G Models 1991-94 Oldsmobile Bravada 1996 Oldsmobile Bravada The crankshaft balancer remover/installer tool J 39046 listed in some 1990-96 service information sections 6A2, 6A3, 6A4, 6A5, 6A6, 6A7, 6A2B, 6A3B, 6A4B, 6A5B, and 6A6B is incorrectly referenced. The correct tool number for the truck models listed above is J 23523-F or equivalent. Page 747 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2584 Fan Clutch: Testing and Inspection Fan Looseness Lateral movement can be observed at the fan blade tip under various temperature conditions because of the type bearing used. This movement should not exceed 1/4 inch (6.5 mm) as measured at the fan tip. If this lateral movement does not exceed specifications, there is no cause for replacement. Page 2532 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Crankshaft Rotation Timing Marks and Indicators: Locations Crankshaft Rotation Crankshaft Rotation (Typical Crankshaft Pulley) Crankshaft rotation is clockwise when viewed from in front of the crankshaft pulley as shown in the generic image. Page 1999 Some run flat tires, such as the Goodyear Extended Mobility Tire (EMT) used on the Corvette, may require more than 275 kPa (40 psi) to seat the bead. In such a case, a tire safety cage must be used. Consult the tire manufacturer for its individual repair policy. Final Inspection 1. After remounting and inflating the tire, check both beads, the repair and the valve with a water and soap solution in order to detect leaks. 2. If the tire continues to lose air, the tire must be demounted and reinspected. 3. Balance the tire and wheel assembly. Refer to Tire and Wheel Assembly Balancing - OFF Vehicle. For additional tire puncture repair information, contact: Rubber Manufacturers Association (RMA) Disclaimer Page 3281 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 745 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 1495 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1585 Harness Connector Faces Page 1833 Fluid - A/T: Testing and Inspection Check fluid at regular intervals. Noticing a change in color, odor or fluid level can serve as a warning of possible transmission problems. To check fluid level, bring fluid to operating temperature of 200°F. With vehicle on a level surface, engine idling in park and parking brake applied, the level on the dipstick should be at the Full mark. To bring the fluid level from the Add mark to the Full mark requires one pint of fluid. If additional fluid is required, use only Dexron II automatic transmission fluid. When adding fluid, do not overfill, as foaming and loss of fluid through the vent may occur as the fluid heats up. Also, If fluid level is too low, complete loss of drive may occur especially when cold, which can cause transmission failure. Page 454 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 2293 12 through 14 in the "in-vehicle" service outlined above. 11. Reinstall the upper main bearing. 12. Reinstall the main cap and lower bearing; torque to 110 N.m (80 lb ft). 13. Repeat for each main bearing. 14. Reinstall oil pump and shield; torque to 88 N.m (65 lb ft). 15. Reinstall dipstick tube. 16. Reinstall oil pan. 17. Reinstall engine in vehicle. 18. Before starting the engine, remove the fuel pump fuse and crank the engine until oil pressure registers on the gauge. Stop cranking, let the starter cool down, then crank for another 15 seconds. 19. Install fuel pump fuse, start engine, check for leaks or unusual noises. 20. Road test vehicle, check for leaks or unusual noises. Correction Category B: Valve Train Clatter, Tick or Click For 1992-94 vehicles equipped with a 4.3L V6 (LB4 VIN Z or L35 VIN W) engine see Corporate Bulletin 376006 for information on converting from net lash to adjustable lash and/or re-lashing the valves on an adjustable lash system. Investigation of "cold knock" is continuing. Updates will continue to be provided when available. Parts Information Check-Valve Filters Description Part Number V6, V8 (Four-Wheel Drive) FRAM PH3980 12555891 V8 (Two-Wheel Drive), Mark V8 PF1218 25160561 The FRAM PH3980 is to be used in place of the PF52. The PH3980 provides superior anti-drainback performance, a key factor in reducing cold knock. FRAM filters are to be procured locally until 08-15-95. After this date the filters may be ordered from GMSPO using the supplied part number. Orders placed to GMSPO prior to this date will not be placed on backorder. Bearings Description Part Number 0.001" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 10120992 0.001" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 10120994 0.002" Main Bearing Kit, Positions 1-4 on V8, 1-3 on V6 12329758 0.002" Main Bearing Kit, Flange # 5 on V8, # 4 on V6 12329792 Main bearing kits are currently available from GMSPO. All calibrations are currently available from GMSPO. Page 1274 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3515 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 685 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Specifications Spark Plug Wire: Specifications RESISTANCE VALUES 0-15 inch cable .................................................................................................................................... ....................................... 3,000 - 10,000 ohms. 15-25 inch cable .................................................................................................................................. ....................................... 4,000 - 15,000 ohms. 25-35 inch cable .................................................................................................................................. ....................................... 6,000 - 20,000 ohms. NOTE: Longer wires should measure about 5,000 to 10,000 ohms per foot. Page 250 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 270 Ignition Control Module: Description and Operation DI Control Module DESCRIPTION The distributor ignition system has a distributor module with four terminals for the IC system that are connected by the control module. To properly control ignition / combustion timing, the control module needs to know: - Crankshaft position. - Engine speed (rpm). - Engine load (manifold pressure or vacuum). - Atmospheric (barometric) pressure. - Engine coolant temperature. IC SYSTEM The IC system consists of the distributor module, a control module, and connecting wires. The four terminals for IC are lettered in the module. The distributor four terminal connector is lettered A-B-C-D. These circuits perform the following functions: Terminal "A" - Reference Ground Lo This wire may be grounded in the distributor. It makes sure the ground circuit, between the module and control module has no voltage drop which could affect performance. If it is open, it may cause poor performance. Terminal "B" - Bypass At about 400 rpm, the control module applies 5 volts to this circuit to switch spark timing control from the module to the control module. An open or grounded bypass circuit will set a DTC 42 and the engine will be at base timing, plus a small amount of advance built into the module. Terminal "C" - Distributor Reference Hi This provides the control module with rpm and crankshaft position information. Terminal "D" - IC This circuit triggers the module. The control module does not know what the actual timing is, but it does know when it gets the reference signal. It then advances or retards the spark from that point. Therefore, if the base timing is set incorrectly, the engine spark curve will be incorrect. Harness View Engine Page 488 Fuse Tester A simple tester (J 34764) can detect a blown fuse. To check a fuse, the tester is applied directly to the fuse in the Fuse Block. Two probes contact the fuse, either into the slots of a flat fuse or to the metal ends of a glass fuse. With power ON, a red Light Emitting Diode (LED) in the tester lights if the fuse is open. The handle of the tester is a tool for removing either type of fuse. Special Tools Diode Replacement Many vehicle electrical systems use a diode to isolate circuits and protect the components from voltage spikes. When installing a new diode, use the following procedure: Page 2618 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Engine Controls - Aftermarket Accessory Usage Engine Control Module: Technical Service Bulletins Engine Controls - Aftermarket Accessory Usage INFORMATION Bulletin No.: 04-06-04-054B Date: November 18, 2010 Subject: Info - Non-GM Parts and Accessories (Aftermarket) Models: 2011 and Prior GM Passenger Cars and Trucks Supercede: This bulletin is being revised to add model years and update to the new U.S. Fixed Operation Manager (FOM) and Canada Warranty Manager (WM) names. Please discard Corporate Bulletin Number 04-06-04-054A (Section 06 - Engine/Propulsion System). The recent rise and expansion of companies selling non-GM parts and accessories has made it necessary to issue this reminder to dealers regarding GM's policy on the use and installation of these aftermarket components. When a dealer is performing a repair under the New Vehicle Limited Warranty, they are required to use only genuine GM or GM-approved parts and accessories. This applies to all warranty repairs, special policy repairs or any repairs paid for by GM. Parts and accessories advertised as being "the same" as parts manufactured by GM, but not sold through GM, do not qualify for use in warranty repairs, special policy repairs or any repairs paid for by GM. During a warranty repair, if a GM original equipment part is not available through GM Customer Care and Aftersales (GM CC&A;), ACDelco(R) distributors, other GM dealers or approved sources, the dealer is to obtain comparable, non-GM parts and clearly indicate, in detail, on the repair order the circumstances surrounding why non-GM parts were used. The dealer must give customers written notice, prior to the sale or service, that such parts or accessories are not marketed or warranted by General Motors. It should also be noted that dealers modifying new vehicles and installing equipment, parts and accessories obtained from sources not authorized by GM are responsible for complying with the National Traffic and Motor Vehicle Safety Act. Certain non-approved parts or assemblies, installed by the dealer or its agent not authorized by GM, may result in a change to the vehicle's design characteristics and may affect the vehicle's ability to conform to federal law. Dealers must fully understand that non-GM approved parts may not have been validated, tested or certified for use. This puts the dealer at risk for potential liability in the event of a part or vehicle failure. If a GM part failure occurs as the result of the installation or use of a non-GM approved part, the warranty will not be honored. A good example of non-authorized modification of vehicles is the result of an ever increasing supply of aftermarket devices available to the customer, which claim to increase the horsepower and torque of the Duramax(TM) Diesel Engines. These include the addition of, but are not limited to one or more of the following modifications: - Propane injection - Nitrous oxide injection - Additional modules (black boxes) that connect to the vehicle wiring systems - Revised engine calibrations downloaded for the engine control module - Calibration modules which connect to the vehicle diagnostic connector - Modification to the engine turbocharger waste gate Although the installation of these devices, or modification of vehicle components, can increase engine horsepower and torque, they may also negatively affect the engine emissions, reliability and/or durability. In addition, other powertrain components, such as transmissions, universal joints, drive shafts, and front/rear axle components, can be stressed beyond design safety limits by the installation of these devices. General Motors does not support or endorse the use of devices or modifications that, when installed, increase the engine horsepower and torque. It is because of these unknown stresses, and the potential to alter reliability, durability and emissions performance, that GM has adopted a policy that prevents any UNAUTHORIZED dealer warranty claim submissions to any remaining warranty coverage, to the powertrain and driveline components whenever the presence of a non-GM (aftermarket) calibration is confirmed - even if the non-GM control module calibration is subsequently removed. Refer to the latest version of Bulletin 09-06-04-026 (V8 Gas Engines) or 06-06-01-007 (Duramax(TM) Diesel Engines) for more information on dealer requirements for calibration verification. These same policies apply as they relate to the use of non-GM accessories. Damage or failure from the use or installation of a non-GM accessory will not be covered under warranty. Failure resulting from the alteration or modification of the vehicle, including the cutting, welding or disconnecting of the vehicle's original equipment parts and components will void the warranty. Additionally, dealers will NOT be reimbursed or compensated by GM in the event of any legal inquiry at either the local, state or federal level that Page 822 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 2073 selection and verification, refer to your paint manufacturer's color book. On wheels that were previous clearcoated aluminum it is recommended that all four wheels and their center caps be refinished to maintain color uniformity. Important: THE PRODUCTS LISTED MUST BE USED AS A SYSTEM. DO NOT MIX OTHER MANUFACTURERS' PRODUCT LINES WITH THE REQUIRED MATERIALS. PRODUCTS LISTED IN THIS BULLETIN HAVE SHOWN THE REQUIRED REPAIR DURABILITY, AND CURRENTLY ARE THE ONLY PAINT SYSTEMS THAT MEET GM SPECIFICATION 4350M-A336. Procedures 1. Remove wheels from vehicle. Tires may remain mounted on wheels. 2. Remove balance weights and mark their location on tire. 3. Wipe excess grease, etc. from wheels with wax and grease remover. 4. Have wheels plastic media blasted to remove clearcoat. FOR FURTHER INFORMATION ON MEDIA BLASTING IN YOUR AREA, CALL US TECHNOLOGIES INC., CONTACT DAVE ROSENBURG AT 1-800-634-9185. Caution: IT IS MANDATORY THAT ADEQUATE RESPIRATORY PROTECTION BE WORN. EXAMPLES OF SUCH PROTECTION ARE: AIR LINE RESPIRATORS WITH FULL HOOD OR HALF MASK. IF NOT AVAILABLE, USE A VAPOR/PARTICULATE RESPIRATOR THAT RESPIRATOR MANUFACTURER RECOMMENDS AS EFFECTIVE FOR ISOCYANATE VAPOR AND MISTS (UNLESS LOCAL REGULATIONS PREVAIL). 5. Painting Process a. Refer to Attachments 1-3 for each System's individual formula and process. b. After following the specific System's individual formula and process, follow these steps: 6. Unmask wheels. 7. Clean all wheel mounting surface of any corrosion, overspray, or dirt. 8. Install new coated balance weights, at marked locations. 9. Replace wheels on vehicle. 10. USE A TORQUE STICK ON AN IMPACT WRENCH, OR A TORQUE WRENCH TO CONSISTENTLY AND UNIFORMLY FASTEN THE WHEEL TO THE SPECIFIED TORQUE FOR THE VEHICLE. THE STAR PATTERN MUST BE FOLLOWED. Important: TORQUE STICKS MUST BE USED ANY TIME AN IMPACT WRENCH IS USED TO TIGHTEN WHEEL NUTS. Warranty Information For vehicles repaired under warranty, use as shown. Attachment 1 - DuPont Products Page 2508 Coolant: Specifications Coolant Capacity, Qts. Less A/C .............................................................................................................................................. ........................................................................... 23 With A/C ............................................................. ........................................................................................................................................................... 25 Radiator Cap Relief Pressure, Lbs. ..................................................................................................... ............................................................................... 15 Thermo. Opening Temp., deg.F ..................... .............................................................................................................................................................. .... 195 Electrical - MIL ON/DTC's Set By Various Control Modules Relay Module: All Technical Service Bulletins Electrical - MIL ON/DTC's Set By Various Control Modules TECHNICAL Bulletin No.: 09-06-03-004D Date: December 08, 2010 Subject: Intermittent No Crank/No Start, No Module Communication, MIL, Warning Lights, Vehicle Messages or DTCs Set by Various Control Modules - Diagnosing and Repairing Fretting Corrosion (Disconnect Affected Connector and Apply Dielectric Lubricant) Models: 2011 and Prior GM Passenger Cars and Trucks Attention: This repair can be applied to ANY electrical connection including, but not limited to: lighting, body electrical, in-line connections, powertrain control sensors, etc. DO NOT over apply lubricant to the point where it prevents the full engagement of sealed connectors. A light coating on the terminal surfaces is sufficient to correct the condition. Supercede: This bulletin is being revised to update the Attention statement and add the 2011 model year. Please discard Corporate Bulletin Number 09-06-03-004C (Section 06 Engine/Propulsion System). Condition Some customers may comment on any of the following conditions: - An intermittent no crank/no start - Intermittent malfunction indicator lamp (MIL) illumination - Intermittent service lamp illumination - Intermittent service message(s) being displayed The technician may determine that he is unable to duplicate the intermittent condition. Cause This condition may be caused by a buildup of nonconductive insulating oxidized debris known as fretting corrosion, occurring between two electrical contact surfaces of the connection or connector. This may be caused by any of the following conditions: - Vibration - Thermal cycling - Poor connection/terminal retention - Micro motion - A connector, component or wiring harness not properly secured resulting in movement On low current signal circuits this condition may cause high resistance, resulting in intermittent connections. On high current power circuits this condition may cause permanent increases in the resistance and may cause a device to become inoperative. Representative List of Control Modules and Components The following is only a representative list of control modules and components that may be affected by this connection or connector condition and DOES NOT include every possible module or component for every vehicle. - Blower Control Module - Body Control Module (BCM) - Communication Interface Module (CIM) - Cooling Fan Control Module - Electronic Brake Control Module (EBCM) - Electronic Brake and Traction Control Module (EBTCM) - Electronic Suspension Control (ESC) Module - Engine Control Module (ECM) - Heating, Ventilation and Air Conditioning (HVAC) Control Module Page 3338 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3550 Disclaimer Diagram Information and Instructions Coolant Temperature Sensor/Switch (For Computer): Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 2531 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 2539 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 565 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 1500 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 2263 Engine Oil: Fluid Type Specifications GM Goodwrench motor oil or equivalent for API Service SG or SG/CE of the recommended viscosity. Notes on Engine Oil Viscosity: Engine oil viscosity (thickness) has an effect on fuel economy and cold-weather operation (starting and oil flow). Lower viscosity engine oils can provide better fuel economy and cold weather performance; however a rise in temperature may require higher viscosity engine oils for satisfactory lubrication. Notice: Using oils of any viscosity other than those viscosities recommended could result in engine damage. When choosing an oil, consider the range of temperatures the vehicle is operated in before the next oil change. Then, select the recommended oil viscosity. Page 3754 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3319 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 480 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3088 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3490 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1013 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1889 Fig. 7 Caliper Bleeding Hose Installation 1. If vehicle is equipped with a vacuum or hydraulic booster, relieve system by applying brakes several times with engine off. 2. Fill master cylinder reservoir with DOT 3 brake fluid. Maintain full level during bleeding procedures. 3. If master cylinder is replaced or suspected to have air in the bore, bleed it before calipers. a. Disconnect forward brake pipe connection at master cylinder and allow brake fluid to flow from connector port, then reconnect pipe but do not tighten. b. Slowly apply brake pedal to allow air to bleed from loose fitting, then tighten fitting before releasing brake pedal. c. Wait 15 seconds, then repeat sequence, including 15 second wait, until all air has been purged from bore. d. After all air has been removed from forward pipe, repeat procedure for rear pipe. 4. If the vehicle is equipped with four wheel anti-lock brakes (4WAL), the Brake Pressure Modular Valve (BPMV) may need to be bled. If the BPMV has been replaced or is suspected of having air trapped inside, bleed system as outlined in "Anti-Lock Brakes chapter." 5. Bleed each wheel in the following sequence: a. Right rear. b. Left rear. c. Right front. d. Left front. 6. Attach a suitable hose to wheel caliper valve and immerse opposite end of hose into a suitable clean container partially filled with clean brake fluid , Fig. 7. 7. Slowly apply brake pedal one time and hold, loosen the bleeder valve to purge air from caliper, then tighten bleeder valve and release pedal. 8. Wait 15 seconds, then repeat sequence, including 15 second wait, until all air is purged from caliper. 9. Repeat bleeding sequence at each wheel until system is bled. 10. Check brake pedal for "sponginess and brake warning lamp for an indication of unbalanced pressure. Repeat bleeding procedure to correct either of these conditions. Pressure Page 758 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 1846 Parts Information Parts are currently available from GMSPO. Shift Indicator Light Application and Operation Air Flow Meter/Sensor Relay: Technical Service Bulletins Shift Indicator Light Application and Operation File In Section: 7 - Transmission Bulletin No.: 36-72-07A Date: February, 1995 Subject: Manual Transmission Shift Indicator Light Application and Operation Models: 1993-95 Chevrolet and GMC Truck C/K and S/T Models with Manual Transmission This bulletin is being revised to add the 1995 model year. Please discard bulletin number 367207 (Group Reference - Transmission). Certain trucks are not equipped with a shift indicator light. The shift light is commonly used to achieve improved fuel economy by prompting the driver when to upshift. Depending on the engine/transmission installed in the vehicle, the shift light can have the following characteristics: ^ Indicates proper shift point for maximum fuel economy. ^ Indicates engine over-speed. ^ Shift light is inoperative. The following charts detail normal shift light operation: 1993 Models: Page 2874 Fuel Pump Relay: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 749 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Controlled Idle Speed Idle Speed: Adjustments Controlled Idle Speed Before performing this check, there should be no DTC(s) displayed, idle air control system has been checked and ignition timing correct. 1. Set parking brake and block drive wheels. 2. Connect a Tech 1 scan tool to the DLC connector with tool in open mode. 3. Start engine and bring it to normal operating temperature. 4. Check for correct state of PRNDL position (R-D-L) switch on Tech 1 scan tool. 5. Check specifications for controlled idle speed and IAC valve pintle position (counts). 6. If within specifications, the idle speed is being correctly controlled by the control module. 7. If not within specifications, refer to Rough, Unstable or Incorrect Idle, Stalling. See: Powertrain Management/Fuel Delivery and Air Induction/Testing and Inspection Page 3374 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Specifications Connecting Rod: Specifications Torque Specification 48 ft.lb Page 234 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 2229 Valve Guide: Service and Repair Valve guides in these engines are an integral part of the head and, therefore, cannot be removed. For service, guide holes can be reamed oversize to accommodate one of several service valves with oversize stems. Check the valve stem clearance of each valve (after cleaning) in its respective valve guide. If the clearance exceeds the service limits of .004 inch on the intake or .005 inch on the exhaust, ream the valve guide to accommodate the next oversize diameter valve stem. Select the reamer for the smallest oversize which will provide a clean straight bore through the valve guide. After reaming, a new seat should be cut into the head to assure perfect seating of the new valve. Page 1924 Fuse Block: Application and ID Convenience Center Convenience Center Cooling System - Coolant Recycling Information Coolant: Technical Service Bulletins Cooling System - Coolant Recycling Information Bulletin No.: 00-06-02-006D Date: August 15, 2006 INFORMATION Subject: Engine Coolant Recycling and Warranty Information Models: 2007 and Prior GM Passenger Cars and Trucks (Including Saturn) 2007 and Prior HUMMER Vehicles 2005-2007 Saab 9-7X Attention: Please address this bulletin to the Warranty Claims Administrator and the Service Manager. Supercede: This bulletin is being revised to adjust the title and Include Warranty Information. Please discard Corporate Bulletin Number 00-06-02-006C (Section 06 - Engine/Propulsion System). Coolant Reimbursement Policy General Motors supports the use of recycled engine coolant for warranty repairs/service, providing a GM approved engine coolant recycling system is used. Recycled coolant will be reimbursed at the GMSPO dealer price for new coolant plus the appropriate mark-up. When coolant replacement is required during a warranty repair, it is crucial that only the relative amount of engine coolant concentrate be charged, not the total diluted volume. In other words: if you are using two gallons of pre-diluted (50:50) recycled engine coolant to service a vehicle, you may request reimbursement for one gallon of GM Goodwrench engine coolant concentrate at the dealer price plus the appropriate warranty parts handling allowance. Licensed Approved DEX-COOL(R) Providers Important: USE OF NON-APPROVED VIRGIN OR RECYCLED DEX-COOL(R) OR DEVIATIONS IN THE FORM OF ALTERNATE CHEMICALS OR ALTERATION OF EQUIPMENT, WILL VOID THE GM ENDORSEMENT, MAY DEGRADE COOLANT SYSTEM INTEGRITY AND PLACE THE COOLING SYSTEM WARRANTY UNDER JEOPARDY. Shown in Table 1 are the only current licensed and approved providers of DEX-COOL(R). Products that are advertised as "COMPATIBLE" or "RECOMMENDED" for use with DEX-COOL(R) have not been tested or approved by General Motors. Non-approved coolants may degrade the Page 1352 Impact Sensor: Service and Repair Forward Discriminating Sensor Prior to performing replacement procedures, disarm air bag system. Refer to, Service and Repair/ Air Bag System Disarming & Air Bag System Arming. Refer to, / Specifications/ Mechanical for torque values when installing components. All sensors and mounting bracket bolts must be carefully torqued to assure proper operation. Never power up the air bag system when any sensor is not rigidly attached to the vehicle, since the sensor could be activated when not attached, causing air bag deployment. 1. Disconnect sensor electrical connector from retainer, then remove connector from Connector Position Assurance (CPA) lock and disconnect. 2. Remove sensor mounting bolts, then the sensor from vehicle. 3. Reverse procedure to install. Ensure arrow is pointed toward front of vehicle. Page 3079 and make the repair. Step 4: Check the repair by performing a System Check on the Headlights Circuit This, of course, means making sure that both HI beams, both LO beams and the HI Beam Indicator are all working. Now suppose that the symptoms were different. You may have operated the Headlamps and found that the LO beams were working, but neither the HI beams nor the HI Beam Indicator were working. Looking at the schematic, you might conclude that it is unlikely that both HI beam filaments and the HI Beam Indicator have all burned out at once. The cause is probably the Headlight Dimmer Switch or its connector. Checking Terminal Contacts DESCRIPTION When diagnosing an electrical system that utilizes Metri-Pack 150/280/480/630 series terminals (refer to Terminal Repair Kit, J 38125-A, J 38125-4 for terminal identification), it is important to check terminal contact between a connector and component, or between in-line connectors, before replacing a suspect component. Frequently, a diagnostic chart leads to a step that reads: Check for poor connection. Mating terminals must be inspected to assure good terminal contact. A poor connection between the male and female terminal at a connector may be the result of contamination or deformation. Contamination is caused by the connector halves being improperly connected, a missing or damaged connector seal, or damage to the connector itself, exposing the terminals to moisture and dirt. Contamination, usually in underhood or underbody connectors, leads to terminal corrosion, causing an open circuit or intermittently open circuit. Page 3453 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 1016 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 1898 Air Bag(s) Arming and Disarming: Service and Repair General Service Precautions CAUTION; When performing service on or around SIR components or SIR wiring, follow the procedures to temporarily disable the SIR system. Failure to follow procedures could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repair. Service and Repair Crankcase Filter: Service and Repair Inspection The crankcase ventilation system should be checked every 30,000 miles and also during regular engine tune-ups. If the crankcase ventilation system includes a breather filter, located in the air cleaner housing, this filter should be replaced whenever the crankcase ventilation valve or air cleaner is replaced. When a periodic inspection indicates the crankcase ventilation is not functioning properly, it should be serviced by replacement only. Page 1479 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1105 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1061 TP Sensor Circuit Page 3164 5-Speed Manual Transmission W/4WD HD Electronic 4-Speed Automatic Overdrive Transmission Page 2921 Fig.2-Symbols (Part 2 Of 3) Page 3504 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 21 Important The following information MUST be documented on the repair order. Failure to do so may result in a chargeback. - Customer vehicle condition. - Was a Service Lamp or Service Message illuminated? If yes, specify which Service Lamp or Service Message. - Was a DTC(s) set? If yes, specify which DTC(s) were set. - After following the procedure contained within this bulletin, could the condition be duplicated? ‹› If the condition was not duplicated, then document the affected module/component connector name and number on the repair order. - If the condition was duplicated after the procedure contained within this bulletin was followed, and additional diagnosis led to the replacement of a module or component, the SI Document ID Number MUST be written on the repair order. Parts Information Alternate Distributor For All of North America Note NyoGel(R) 760G Lubricant* is equivalent to GMSPO P/N 12377900, and P/N 10953529 (Canada), specified for use to correct the condition in this bulletin. *We believe this source and their products to be reliable. There may be additional manufacturers of such products/materials. General Motors does not endorse, indicate any preference for, or assume any responsibility for the products or material from this firm or for any such items that may be available from other sources. Warranty Information (excluding Saab Models) For vehicles repaired under warranty, use the appropriate/closest labor operation depending upon the module/component connection that the dielectric lubricant was applied to: Warranty Information (Saab Models) Page 3512 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Diagram Information and Instructions Engine Control Module: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Page 3083 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Service and Repair Oil Line: Service and Repair ENGINE OIL COOLER LINE REPLACEMENT The optional oil cooler is either an integral pan of the radiator or a separate unit placed in front of the radiator. Cooler lines and hoses are serviceable. OIL COOLER SYSTEM SERVICE If foreign material has entered the oil cooler or if the engine has been damaged internally, flush the oil cooler, connecting lines, and filter adapter assembly in the following manner. Engine Oil Cooler (7.4L Engine Without Heavy Duty Cooling) Engine Oil Cooler (7.4L Engine With Heavy Duty Cooling) Page 3300 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Aluminum Wheels - Refinishing Technical Service Bulletin # 531703A Date: 960501 Aluminum Wheels - Refinishing File In Section: 10 - Body Bulletin No.: 53-17-03A Date: May, 1996 INFORMATION Subject: Aluminum Wheel Refinishing Models: 1991-96 Passenger Cars and Trucks This bulletin is being revised to delete the 1990 model year and add the 1996 model year. Please discard Corporate Bulletin Number 53-17-03 (Section 10 - Body). This bulletin supersedes and cancels all previous service bulletins concerning the refinishing of aluminum wheels. The purpose of this service bulletin is to assist dealerships in repairing the discoloration or surface degradation that has occurred on styled aluminum wheels. This bulletin provides NEW PROCEDURES AND SPECIFIC MATERIALS for the refinishing of painted aluminum wheels or aluminum wheels with discoloration or surface degradation. Important: THE RE-MACHINING OF ALUMINUM WHEELS IS NOT RECOMMENDED. THE RE-CLEAR COATING OF ALUMINUM WHEELS IS NO LONGER RECOMMENDED DUE TO CONCERNS OF REPAIR DURABILITY The new procedure requires the wheel surface be plastic media blasted to remove old paint or clear coat. CHEMICAL STRIPPERS ARE NOT RECOMMENDED. Material Required System 1: DuPont Products 3939-S Cleaning Solvent 615/616 Etching Primer URO 5000 Primer Surfacer IMRON 6000 Basecoat 3440-S IMRON Clear System 2: PPG Products DX533 Aluminum Cleaner DX503 Aluminum Conditioner DP Epoxy Primer Deltron Basecoat (DBC) Concept 2001 Clear Acrylic Urethane System 3: Spies Hecker Permahyd Silicone Remover 7090 Permahyd 1:1 Primer 4070 Permahyd 2:1 Surfacer 5080 Permahyd Base Coat Series 280/285 Permahyd H.S. Clearcoat 8060 Color Selection If the wheels being painted were previously clearcoated aluminum, we would recommend using Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle SILVER WA9967 for a very bright look. As an option to the customer, you may also use body color. For color Page 613 15730044 Shim, Med. Beige 1 15730045 Shim, Neutral Med 1 Parts are currently available from GMSPO. Warranty Information For vehicles repaired under warranty, use: Labor Operation Description Labor Time A9780 Rt. Panel, Front Door Inner Repair 0.2 Hr A9781 Left Panel, Door Inner Repair 0.2 Hr Page 1445 setting to detect intermittents, it is necessary to connect the meter to the circuit. Following are examples of the various methods of connecting the meter to the circuit to be checked: ^ Backprobe both ends of the connector and either hold the leads in place while manipulating the connector or tape the leads to the harness for continuous monitoring while performing other operations or test driving. (Do not backprobe "Weather Pack(R)" type connectors.) ^ Disconnect the harness at both ends of the suspect circuit where it connects either to a component or to other harnesses. ^ Use Connector Test Adapter Kit J 35616-A to connect the meter to the circuit. ^ If the system being diagnosed has a specified Pinout or breakout box, it may be used to simplify connecting the meter to the circuit or for checking multiple circuits quickly. Aftermarket Accessories Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the problems. Some possible causes of vehicle problems related to aftermarket accessories include: 1. Power feeds connected to points other than the Battery. 2. Antenna location. 3. Transceiver wiring located too close to vehicle electronic modules or wiring. 4. Poor shielding or poor connectors on antenna feed line. Probing (Frontprobe & Backprobe) After probing, when reconnecting connectors or replacing terminals, always be sure to reinstall Connector Position Assurance (CPA) and Terminal Position Assurance (TPA). Frontprobe When frontprobing of connectors is required, always use a mating terminal adapter from Connector Test Adapter Kit (J 35616-A). The use of proper adapters will ensure that proper terminal contact integrity is maintained. (refer to Procedures in Checking Terminal Contact). Backprobe Only backprobe connector terminals when specifically called for in diagnostic procedures. Since backprobing can be a source of damage to connector terminals, extra care must be taken to avoid deforming the terminal, either by forcing the test probe too far into the cavity or by using too large a test probe. After backprobing any connector, always check for terminal damage. If terminal damage is suspected, check for proper terminal contact, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Testing For Voltage Voltage Check 1. Connect one lead of a test light to a known good ground. When using a Digital Voltmeter (DVM), be sure the voltmeter's negative lead is connected to ground. 2. Connect the other lead of the test light or voltmeter to a selected test point (connector or terminal). 3. If the test light illuminates, there is voltage present. When using a DVM, note the voltage reading. Page 1086 HD 5-Speed Manual Transmission 5-Speed Manual Transmission Page 3710 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Diagram Information and Instructions Throttle Position Sensor: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Gauge Does Not Move From Cold When Engine Is Hot Temperature Gauge: Testing and Inspection Gauge Does Not Move From Cold When Engine Is Hot This condition is generally caused by a blown fuse, open circuit or faulty sensor. 1. Check fuse, replace if necessary. 2. Turn ignition switch to On position, then remove lead at sensor unit. 3. Connect test lamp from sensor lead to ground, lamp should glow. Short sensor lead to ground, gauge should indicate "Hot." 4. If gauge indicated HOT, check lead on sensor. If satisfactory, replace sensor. If gauge indicates COLD, replace cluster. Locations Engine Page 2592 Coolant Temperature Sensor/Switch (For Computer): Locations Component View Engine Coolant Temperature (ECT) Sensor The Engine Coolant Temperature (ECT) Sensor is located on the intake manifold next to the thermostat housing. Harness View Engine Page 422 Heater And A/C Control Select SW (C2), Stop Lamp & TCC Switch Jumper, Aux Fan Control SW Page 3908 6. Checks for open or grounded CKT 439. 7. Checks for open CKT 543 or faulty control module. DIAGNOSTIC AIDS Check all connections. If OK, refer to Diagnosis By Symptom / Intermittents See: Testing and Inspection/Symptom Related Diagnostic Procedures/Intermittent Condition IAC valve reset procedure: ^ Disconnect battery terminal for 10 seconds, then reconnect terminal. ^ Ignition "ON," engine "OFF" for 5 seconds. ^ Ignition "OFF" for 10 seconds. Page 1233 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3750 ^ Diesel Glow Plug Circuit General Information OPEN CIRCUIT An open circuit is an incomplete circuit. Power cannot reach the load or reach ground. If a circuit is open, active components do not energize. SHORT CIRCUIT A short circuit is an unwanted connection between one part of the circuit and either ground or another part of the circuit. A short circuit causes a fuse to blow or a circuit breaker to open. Heated Oxygen Sensor (O2S) Repair If the Heated Oxygen Sensor pigtail wiring, connector or terminal is damaged, the entire Oxygen Sensor Assembly must be replaced. Do not attempt to repair the wiring, connector or terminals. In order for the sensor to function properly, it must have provided to it a clean air reference. This clean air reference is obtained by way of the Oxygen Sensor signal and heater wires. Any attempt to repair the wires, connectors or terminals could result in the obstruction of the air reference and degraded Oxygen Sensor performance. The following guidelines should be used when servicing the Heated Oxygen Sensor: ^ Do not apply contact cleaner or other materials to the sensor or vehicle harness connectors. These materials may get into the sensor causing poor performance. Also the sensor pigtail and harness wires must not be damaged in such a way that the wires inside are exposed. This could provide a path for foreign materials to enter the sensor and cause performance problems. ^ Neither the sensor or vehicle lead wires should be bent sharply or kinked. Sharp bends, kinks, etc., could block the reference air path through the lead wire. ^ Do not remove or defeat the Oxygen Sensor ground wire (where applicable). Vehicles that utilize the ground wired sensor may rely on this ground as the only ground contact to the sensor. Removal of the ground wire will also cause poor engine performance. ^ To prevent damage due to water intrusion, be sure that the peripheral seal remains intact on the vehicle harness connector. The Engine Harness may be repaired using Packard's Crimp and Splice Seals Terminal Repair Kit J 38125-A. Under no circumstances should repairs be soldered since this could result in the air reference being obstructed. General Information ^ The following general repair procedures can be used to repair most types of connectors. The repair procedures are divided into three general groups: Push-to-Seat, Pull-to-Seat and Weather Pack(R). ^ Use the proper Pick(s) or Tool(s) that apply to the terminal. ^ The Terminal Repair Kit (J 38125-A) contains further information. Push-to-Seat and Pull-to-Seat Connectors Typical Push-to-seat Connector And Terminal Page 3494 Autofuse The Autofuse, normally referred to simply as "Fuse," is the most common circuit protection device in today's vehicle. The Autofuse is most often used to protect the wiring assembly between the Fuse Block and the system components. Maxifuse The Maxifuse was designed to replace the fusible link and Pacific Fuse elements. The Maxifuse is designed to protect cables, normally between the battery and fuse block, from both direct short circuits and resistive short circuits. Compared to a fusible link or a Pacific Fuse element, the Maxifuse performs much more like an Autofuse, although the average opening time is slightly longer. This is because the Maxifuse was designed to be a slower blowing fuse, with less chance of nuisance blows. Minifuse The Minifuse is a smaller version of the Autofuse and has a similar performance. As with the Autofuse, the Minifuse is usually used to protect the wiring assembly between a fuse block and system components. Since the Minifuse is a smaller device, it allows for more system specific fusing to be accomplished within the same amount of space as Autofuses. Pacific Fuse Element/Maxifuse The Pacific Fuse Element and Maxifuse were developed to be a replacement for the fusible link. Like a fusible link, the fuses are designed to protect wiring from a direct short to ground. These elements are easier to service and inspect than a fusible link and will eventually replace fusible links in all future vehicle applications. Fusible Links Good And Damaged Fusible Links In addition to circuit breakers and fuses, some circuits use fusible links to protect the wiring. Like fuses, fusible links are "one-time" protection devices that will melt and create an open circuit. Not all fusible link open Circuits can be detected by observation. Always inspect that there is battery voltage past the fusible link to verify continuity. Page 281 Air Bag Control Module: Description and Operation A function of the DERM is to supply the deployment loop with a 36 volt loop reserve to ensure sufficient energy to deploy the air bag if the ignition feed to the arming sensor is lost during a frontal collision. Another function of the DERM is electrical system diagnostics. The DERM can detect circuit and component malfunctions within the deployment loop. Voltage drops across components within the loop are measured during non-deployment conditions. If the monitored voltages fall outside of the expected limits, the DERM will indicate a malfunction through the storage of a diagnostic trouble code and the illumination of the air bag warning light. Description and Operation Oil Pressure Warning Lamp/Indicator: Description and Operation Many trucks use a warning light on the instrument panel in place of the conventional dash indicating gauge to warn the driver when the oil pressure is dangerously low. The warning light is wired in series with the ignition switch and the engine unit--which is an oil pressure switch. The oil pressure switch contains a diaphragm and a set of contacts. When the ignition switch is turned on, the warning light circuit is energized and the circuit is completed through the closed contacts in the pressure switch. When the engine is started, build-up of oil pressure compresses the diaphragm, opening the contacts, thereby breaking the circuit causing the light to go out. Page 1276 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 2599 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 630 Following the procedure described in Section 8A of the Service Manual, remove the Sender Assembly and replace the original Float and Arm with P/N 25312833 (see Figure 2). Reinstall the Sender Assembly and Tank. Parts Information P/N Description Qty 25312833 Float Kit, Fuel Level Sensor 1 The part is currently available from GMSPO. Warranty Information For vehicles repaired under warranty, use: Labor Operation Description Labor Time L1225 Sender Use published Assembly, Fuel Labor Operation (Tank Unit) - Time Replace Important: Labor operation is coded to base vehicle coverage in the warranty system. Page 1204 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 3668 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 499 Proper Taping Step 5: Tape the Cable Tape over the entire cable using a winding motion. This tape will replace the section of the jacket you removed to make the repair. Terminal Repairs Terminal Repair The following repair procedures can be used to repair Push-to-Seat, Pull-to-Seat or Weather Pack(R) terminals. Some terminals do not require all steps shown. Skip those that don't apply. The Terminal Repair Kit (J 38125-A) contains further information. Step 1: Cut off terminal between core and insulation crimp (minimize wire loss) and remove seal for Weather Pack(R) terminals. Step 2: Apply correct seal per gauge size of wire and slide back along wire to enable insulation removal (Weather Pack(R) terminals only). Step 3: Remove insulation. Step 4: Align seal with end of cable insulation (Weather Pack(R) terminals only). Step 5: Position strip (and seal for Weather Pack(R)) in terminal. Step 6: Hand crimp core wings. Step 7: Hand crimp insulation wings (non-Weather Pack(R)). Hand crimp insulation wings around seal and cable (Weather Pack(R)). Step 8: Solder all hand crimped terminals. Page 2875 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3709 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 387 Fig.1-Symbols (Part 1 Of 3) Page 660 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2750 Temperature Gauge: Testing and Inspection Gauge Indicates Hot When Engine Is Cold This condition is generally caused by a shorted or grounded circuit. 1. Remove sensor lead at sensor unit. Gauge should move to COLD position, if not check unit for a external short. If no external short is found, replace sensor. 2. If gauge stays HOT, check for a short circuit in gauge to sensor wiring. If circuit is satisfactory, replace cluster. Diagram Information and Instructions Brake Switch - TCC: Diagram Information and Instructions Abbreviation A/C Air Conditioning CCM Central Control Module CKT Circuit CONN Connector EBCM Electronic Brake Control Module EBTCM Electronic Brake and Traction Control Module ECM Engine Control Module HARN Harness I/P Instrument Panel LH Left Hand PCM Powertrain Control Module RH Right Hand TERM Terminal Cell References CELL REFERENCES General Motors vehicles often use "CELL" references in their electrical wiring diagrams. These references are used in the Original Equipment Manual to refer to a section in the manual and not a specific diagram(s). GM Sample Diagram W/ Cell Reference For instance, in the diagram illustrated "Cell 20" is not a reference to another diagram but a reference to "Section 20" in the OE manual. In the example, "Section 20" is the engine control section of the manual. To navigate through these "Cell" references start at the vehicle level and go to: Diagrams / Electrical Diagrams - for a complete list of the diagrams available for the vehicle. Choose the system you are working on and view those diagrams. Note: If unsure of the system - try utilizing the search feature. Type a component in the search feature that belongs to the system and when the results are displayed note the path displayed. This will show the system the component belongs in. Electrostatic Discharge (ESD Sensitive Devices) All Electrostatic Discharge (ESD) sensitive components are Solid State and the following information applies to them. Specifications Throttle Position Sensor: Specifications Idle (normal) ........................................................................................................................................ ....................................................... 0.45 to 0.95 volts (maximum) ........................................................................................................................................... .......................................................... 1.25 volts Wide Open Throttle ............................................................................................................................. ........................................................... 4.0 to 4.5 volts The Throttle position Sensor is not adjustable on this engine but should read below 1.25 volts at closed throttle and about 4.5 volts at wide open throttle. Page 1325 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3221 Deformation Of A Typical Metri-Pack 150/280/480/630 Series Female Terminal Deformation is caused by probing the mating side of a connector terminal without the proper adapter, improperly joining the connector halves or repeatedly separating and joining the connector halves. Deformation, usually to the female terminal contact tang, can result in poor terminal contact, causing an open or intermittently open circuit. PROCEDURE Follow the procedure below to check terminal contact. 1. Separate the connector halves. Refer to Terminal Repair Kit, J 38125-A, J 38125-4. 2. Inspect the connector halves for contamination. Contamination will result in a white or green build-up within the connector body or between terminals, causing HI terminal resistance, intermittent contact or an open circuit. An underhood or underbody connector that shows signs of contamination should be replaced in its entirety: terminals, seals and connector body. 3. Using an equivalent male terminal from the Terminal Repair Kit, J 38125-A, check the retention force of the female terminal in question by inserting and removing the male terminal to the female terminal in the connector body. Good terminal contact will require a certain amount of Page 280 Description Page 1773 19. Pull back access door on the upper evaporator case carefully to prevent breaking the case (Figure 1). Align the TXV capillary against the evaporator outlet tube being sure not to damage the capillary line. Place the first holding clamp so it is located 1/4" or less below the crimp in the capillary tube (Figure 3). Install the second clamp 1/4" or less below the first clamp. Be sure the clamps are fully seated on the tube and that the capillary is retained in the formed seat of each clamp (Figure 3, Section 1-1). Notice: After all components are installed, evacuate and charge the A/C system. Leak test all joints that were opened. 20. Using a heat gun to soften the plastic case, close both access doors and align the edges of the plastic. Using a soldering gun, melt both edges of the case together along the full length of the cuts, as smoothly as possible. 21. Cover the soldered closures with duct tape to prevent air leakage. 22. Reinstall the right side trim panel, the D-pillar trim, the C-pillar trim, the C-pillar seat belt retainer and the rear bench seat. Page 2652 Auxiliary Heater Module Install or Connect 1. Heater core. 2. Heater case cover. 3. Blower motor, if necessary. 4. Heater module. 5. Nuts. 6. Bolts. Tighten Nuts to 10 Nm (89 lb in). - Bolts to 1.5 Nm (13 lb in). 7. Drain valve. 8. Electrical connectors, as necessary. 9. Auxiliary heater hoses to heater core. 10. Right rear wheelhouse. 11. Right rear quarter trim panel. 12. Engine coolant. - Check the system for leaks. Page 2379 Oil Pressure Warning Lamp/Indicator: Testing and Inspection The oil pressure warning light should go on when the ignition is turned on. If it does not light, disconnect the wire from the engine unit and ground the wire to the frame or cylinder block. Then if the warning light still does not go on, replace the bulb. If the warning light goes on when the wire is grounded, check the engine unit for a poor ground, or improper installation. (The presence of sealing compound on the threads of the engine unit will cause a poor ground.) If the unit is found to be properly grounded and installed, replace the unit. If the warning light remains lit when it normally should be out, replace the engine unit before proceeding to determine the cause for low pressure indication. The warning light will sometimes light or flicker when the engine is idling, even if oil pressure is adequate. However, the light should go out when the engine speed is increased. Page 710 15730044 Shim, Med. Beige 1 15730045 Shim, Neutral Med 1 Parts are currently available from GMSPO. Warranty Information For vehicles repaired under warranty, use: Labor Operation Description Labor Time A9780 Rt. Panel, Front Door Inner Repair 0.2 Hr A9781 Left Panel, Door Inner Repair 0.2 Hr Page 2905 Idle/Throttle Speed Control Unit: Adjustments Idle Speed Control Actuator Adjustment Procedure: - Before adjusting ISC actuator you must first check the minimum idle speed to be within specifications. Refer to SPECIFICATIONS/IDLE SPEED. (ISC actuator must have vacuum applied so that it is not contacting the throttle lever.) See image VIEW A. - Remove vacuum hose on ISC actuator on warm engine. - Adjust ISC actuated idle speed to 1300 +/- 50 rpm. See image VIEW B. - Install vacuum hose. Page 516 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 69 Important: Cruise control module ribbon must not be twisted when installed to cruise control module. 2. Install cruise control module per Section 9B of the Service Manual. 3. Connect cruise control cable end fitting to throttle body lever stud. If vehicle is equipped with accelerator control/cruise control cable adjuster (throttle relaxer), connect cruise control cable end fitting to adjuster. Note correct location of pulley for end fitting. 4. Adjust cruise cable per "Cable Assembly Adjustment" procedure in Section 9B of the Service Manual. Important: Excessive cable slack in cruise control cable will result in perceived slow module response. PARTS INFORMATION Parts are currently available from GMSPO. WARRANTY INFORMATION For vehicles repaired under warranty, use: Labor Operation Description Labor Time R1220 Module, C/C Replace Use Published Labor Operation time Page 998 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 3421 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 3958 Knock Sensor Circuit Page 1554 Warranty Information Some owners with actuators that are operating as designed (5-30 seconds engagement time) may choose to upgrade to the fast actuator at their own expense. The fast actuator is a new product enhancement and should not be used to replace actuators that are operating as designed. For vehicles repaired under warranty, use: Service Procedure 1. Remove the front differential carrier shield, if equipped. 2. If necessary, clean the axle housing in the area around the existing actuator. Disconnect the actuator's electrical connection at the front axle housing. 3. Remove the front axle actuator by unthreading the actuator from the axle housing. 4. Install the spacer from the wiring kit into the axle tube with the flat side seated against the shift fork. 5. Install the actuator motor and tighten until the shoulder of the actuator seats against the axle tube. Important: If binding occurs before the actuator is seated, remove the actuator and reseat the spacer by pushing on the spacer with a screwdriver. Then reinstall the actuator. On K3 Models with the cast iron axle tube, there may be a casting burr which may contact the edge of the actuator. This should not create a concern and the actuator should seat against the axle tube. If this contact remains a concern, use a die grinder in order to remove the burr. Page 3602 Valve Clearance: Specifications Valve Arrangement FRONT TO REAR 7.4L/V8-454 ......................................................................................................................................... ........................................................... E-I-E-I-E-I-E-I Page 922 Knock Sensor: Testing and Inspection Knock Sensor Check Page 3070 Fig.2-Symbols (Part 2 Of 3) Engine - Noise/Damage Oil Filter Application Importance Oil Filter: All Technical Service Bulletins Engine - Noise/Damage Oil Filter Application Importance INFORMATION Bulletin No.: 07-06-01-016B Date: July 27, 2009 Subject: Information on Internal Engine Noise or Damage After Oil Filter Replacement Models: 2010 and Prior Passenger Cars and Trucks (Including Saturn) 2010 and Prior HUMMER H2, H3 2009 and Prior Saab 9-7X Supercede: This bulletin is being updated to add model years. Please discard Corporate Bulletin Number 07-06-01-016A (Section 06 - Engine/Propulsion System). Important Engine damage that is the result of an incorrect or improperly installed engine oil filter is not a warrantable claim. The best way to avoid oil filter quality concerns is to purchase ACDelco(R) oil filters directly from GMSPO. Oil filter misapplication may cause abnormal engine noise or internal damage. Always utilize the most recent parts information to ensure the correct part number filter is installed when replacing oil filters. Do not rely on physical dimensions alone. Counterfeit copies of name brand parts have been discovered in some aftermarket parts systems. Always ensure the parts you install are from a trusted source. Improper oil filter installation may result in catastrophic engine damage. Refer to the appropriate Service Information (SI) installation instructions when replacing any oil filter and pay particular attention to procedures for proper cartridge filter element alignment. If the diagnostics in SI (Engine Mechanical) lead to the oil filter as the cause of the internal engine noise or damage, dealers should submit a field product report. Refer to Corporate Bulletin Number 02-00-89-002I (Information for Dealers on How to Submit a Field Product Report). Disclaimer Warranty - Guidelines for Using E0420 Wheel Replace Wheels: All Technical Service Bulletins Warranty - Guidelines for Using E0420 Wheel Replace File In Section: Warranty Administration Bulletin No.: 72-05-05 Date: August, 1997 WARRANTY ADMINISTRATION Subject: Guidelines for Using EO42O Wheel Replace Models: 1989-98 Passenger Cars and Light Duty Trucks The purpose of this bulletin is to provide service personnel with guidelines for using the above subject labor operation. Effective with repair orders dated on or after September 1, 1997, dealers are to be guided by the following: ^ Aluminum Wheels (including chrome plated) with Porosity - Wheels that exhibit porosity should be repaired as described in the vehicle service manual. Wheels should not be replaced without wholesale approval. ^ Aluminum Wheels (except chrome plated) with a "Finish Defect" - Wheels that exhibit a defect in the finish, (i.e., discoloration or surface degradation) should be refinished as described in the Corporate Service Bulletin Number 53-17-03A released in May, 1996. ^ Chrome Wheels - Wheels that are chromed and found to have a finish defect can only be replaced. ^ Aluminum and chrome wheels replaced under warranty will be subject to random part review and inspection. Those wheels inspected and found not to be defective and/or should have been repaired, will be subject to charge back. Wheels damaged by normal wear, road hazards, car wash brushes, or other physical or chemical damage are not eligible for warranty coverage. Page 1820 Coolant: Specifications Coolant Capacity, Qts. Less A/C .............................................................................................................................................. ........................................................................... 23 With A/C ............................................................. ........................................................................................................................................................... 25 Radiator Cap Relief Pressure, Lbs. ..................................................................................................... ............................................................................... 15 Thermo. Opening Temp., deg.F ..................... .............................................................................................................................................................. .... 195 Page 2721 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground 4L60-E (M30) Transmission Fluid Pressure Sensor/Switch: Description and Operation 4L60-E (M30) Transmission TRANSMISSION FLUID PRESSURE SWITCH ASSEMBLY Important: Seven valid components and two invalid combinations are available from the PSA: Valid combinations for Circuit A, B and C are shown. Invalid combinations are the following: A=OV, B=Ov AND C=OV - A=OV, B=12v AND C=OV The Transmission Fluid Pressure Switch Assembly (PSA) is a set of five pressure switches on the valve body that sense whether fluid pressure is present in five different valve body passages. The combination of which switches are open and closed is used by the PCM in order to determine actual manual valve position. The PSA assembly, however, cannot distinguish between PARK and NEUTRAL because the monitored valve body pressures are identical in both cases. The switches are wired to provide three signal lines that are monitored by the PCM. These inputs are used to help control the line pressure, the torque converter clutch apply and the shift solenoid operation. Voltage at each of the signal lines is either zero or twelve volts. In order to monitor the PSA assembly operation, the PCM compares the actual voltage combination of the switches to a PSA combination chart stored in its memory. If the PCM sees one of two illegal voltage combinations, a code 028 will result. A Code 028 indicates a short circuit condition in either the range signal A or the range signal C circuits. The PSA assembly signal voltage can be measured from each pin-to-ground and compared to the combination chart. On the transmission wiring harness, pin N is range signal A, pin R is range signal B and pin P is range signal C. With the wiring harness connected and the engine running, a voltage measurement of these three lines will indicate a high reading (near 12 volts) when a circuit is open, and a low (zero volts) when the circuit is switched to ground. The transmission temperature sensor is part of the transmission fluid pressure switch assembly. Page 3740 ^ Before replacing a component, check power, signal and ground wires at the component harness connector. If the checks and connections are OK, the most probable cause is component failure. Step 4: Test the Repair Repeat the System Check to verify that the fault has been corrected and that no other faults were induced during the repair. EXAMPLE: A customer brings in a vehicle and says that the HI beams do not work. Step 1: Perform a System Check on the Headlight Circuit You may discover that both LO beams operate. In HI, you may notice that the HI Beam Indicator comes ON, but neither HI beam operates. Typical Headlights Schematic Step 2: Read the Headlights Electrical Schematic This is the step that will save time and labor. Remember, it is essential to understand how a circuit should work, before trying to figure out why it doesn't. After you understand how the circuit should operate, read the schematic again, this time keeping in mind what you have learned by operating the circuit. Since both LO beams work, you know that the Headlight Switch, the YEL wire, the LO contacts of the Headlight Dimmer Switch, terminal "1E" of C100, the TAN wires and grounds G1O5 and G109 are all good. Furthermore, since you saw that the HI Beam Indicator came ON when the Headlight Dimmer Switch was moved to HI you know that the HI contacts of the Headlight Dimmer Switch and the LT GRN wire between the Headlight Dimmer Switch and C100 are good. At this point, you could test for voltage at the RH Headlamp with the Headlight Dimmer Switch in HI. However, it is extremely unlikely that the HI beam filaments have burned out in both headlamps, or that both headlamps connections are bad. The cause must be a bad connection at C100, or a break in the LT GRN wire between C100 and the RH Headlamp. You have quickly narrowed the possible causes down to one specific area, and have done absolutely no work on the vehicle itself. Step 3: Find the fault and repair it Using the Component Location List and the corresponding figure, you can quickly find C100 and the LT GRN wire, locate the exact trouble point Page 3326 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Number 1 Cylinder Location Page 1798 Hose/Line HVAC: Service and Repair Evaporator Tube Remove or Disconnect 1. Negative battery cable. 2. Recover refrigerant. 3. Auxiliary heater pipe, if equipped. 4. Coolant recovery reservoir. 5. Evaporator tube from evaporator. 6. O-ring seal. 7. Evaporator tube from condenser. 8. O-ring seal. Install or Connect 1. Evaporator tube into clip. 2. New O-ring seal. - Coat O-ring seal with 525 viscosity refrigerant oil. 3. Evaporator tube to condenser. Tighten Evaporator tube to 24 Nm (18 lb ft). 4. New O-ring seal. - Coat O-ring seal with 525 viscosity refrigerant oil. 5. Evaporator tube to evaporator. Tighten Evaporator tube to 24 Nm (18 lb ft). 6. Coolant recovery reservoir. 7. Auxiliary heater pipe, if equipped. 8. Negative battery cable. 9. Charge system. - Check system for leaks. Page 1299 A. On G, J and N Models: DO NOT REMOVE THE STEERING COLUMN as indicated in the Service Manual procedure. 1. Remove the tilt lever, upper and lower column covers. 2. Drill hole in module housing as indicated in the illustration using a short drill bit (1/8" followed by 9/32") and 90 degree drill motor or go degree drill attachment to break or access the retaining spring for the lock cylinder button, see Figure 2. 3. Using a pick or needle nose pliers, remove the retaining spring from the hole. 4. Using pliers, grasp and remove the retaining button for the cylinder. 5. Remove the cylinder from the housing. 6. Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. 7. Install the new cylinder and reinstall the steering column components. B. On U, W, and light duty trucks, follow the Service Manual procedure for keys missing, or cylinders won't rotate. Procedure: Instrument Panel Mounted Switches Important: This new procedure involves drilling a hole through the plastic ignition switch and into the lock cylinder slightly to break or access a cylinder release button retaining spring (similar to G, J and N models). The removal of the broken spring and then the release button will allow the switch to be reused. 1. Remove the necessary trim panels to gain access to the instrument panel mounted switch (refer to information in "Body and Accessories Section, Instrument Panel, Gauges and Consoles"). a. On instrument panel mounted N models (Malibu and Cutlass), the switch and cylinder can be accessed after removing the instrument cluster assembly and positioning the switch/cylinder upward in the cavity for the cluster assembly. b. On Corvette models, the switch and cylinder can be accessed after removing the knee bolster from the lower instrument panel area and positioning the switch/cylinder downward from its location on the instrument panel. 2. Loosen switch from instrument panel and disconnect the electrical connections, BUT NOT the cable connection for BTSI (Brake/Transmission Shift Interlock). 3. Protect the immediate work area with a fender cover or other suitable material. Page 978 ^ Throttle angle is greater than 5%. Page 3457 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 3361 circuit when the current exceeds a given level for a sufficient time. The action is non-reversible and the fuse must be replaced each time a circuit is overloaded or after a malfunction is repaired. Fuse Rating And Color Fuses are color coded. The standardized color identification and ratings are shown. For service replacement, non-color coded fuses of the same respective current rating can be used. Examine a suspect fuse for a break in the element. If the element is broken or melted, replace the fuse with one of equal current rating. There are additional specific circuits with in-line fuses. These fuses are located within the individual wiring harness and will appear to be an open circuit if blown. Page 3134 Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of wire later if you decide to cut more wire to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. This will help prevent moisture from bridging adjacent splices and causing damage. Wire Size Conversion Table Step 3: Strip the Insulation If it is necessary to add a length of wire to the existing harness, be certain to use the same size as the original wire. To find the correct wire size either find the wire on the schematic and convert the metric size to the equivalent AWG size or use an AWG wire gage. If unsure about the wire size, begin with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Strip approximately 7.5 mm (5/16 in.) of insulation from each wire to be spliced. Be careful to avoid nicking or cutting any of the wires. Check the stripped wire for nicks or cut strands. If the wire is damaged, repeat this procedure after removing the damaged section. Crimp And Seal Splice Sleeve Chart Step 4: Select and Position the Splice Sleeve Select the proper splice sleeve according to wire size. The splice sleeves and tool tests are color coded (refer to Chart). Hand Crimp Tool Using the J 38125-8 splice crimp tool, position the splice sleeve in the proper color nest of the hand crimp tool. Place the splice sleeve in the nest so that the crimp falls midway between the end of the barrel and the stop. Page 3036 Wire Size Conversion Table Fusible links are used instead of a fuse in wiring circuits that are not normally fused, such as the ignition circuit. For AWG sizes, each fusible link is four wire gage sizes smaller than the wire it is designed to protect. For example: to protect a 10 gage wire use a 14 gage link or for metric, to protect a 5 mm Sq. wire use a 2 mm Sq. link, refer to Wire Size Conversion Table. Links are marked on the insulation with wire-gage size because the heavy insulation makes the link appear to be a heavier gage than it actually is. The same wire size fusible link must be used when replacing a blown fusible link. Fusible links are available with three types of insulation: Hypalon(R), Silicone/GXL (SIL/GXL) and Expanded Duty. All future vehicles that use fusible links will utilize the Expanded Duty type of fusible link. When servicing fusible links, all fusible links can be replaced with the Expanded Duty type. SIL/GXI fusible links can be used to replace either SIL/GXI or Hypalon(R) fusible links. Hypalon(R) fusible links can only be used to replace Hypalon(R) fusible links. Determining characteristics of the types of fusible links are: Hypalon(R) (limited use): only available in 0.35 mm Sq. or smaller and its insulation is one color all the way through. - SIL/GXL (widely used): available in all sizes and has a white inner core under the outer color of insulation. - Expanded Duty: available in all sizes, has an insulation that is one color all the way through and has three dots following the writing on the insulation. Service fusible links are available in many lengths. Choose the shortest length that is suitable. If the fusible link is to be cut from a spool, it should be cut 150-225 mm (approx. 6-9 in.) long. NEVER make a fusible link longer than 225 mm (approx. 9 in.). CAUTION: Fusible links cut longer than 225 mm (approx. 9 in.) will not provide sufficient overload protection. Page 1220 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 1328 Step 1: Open the Harness If the diode is taped to the harness, remove all of the tape. Step 2: Remove inoperative Diode Paying attention to current flow direction, remove inoperative diode from the harness with a suitable soldering tool. If the diode is located next to a connector terminal, remove the terminal(s) from the connector to prevent damage from the soldering tool. Step 3: Strip the Insulation Carefully strip away a section of insulation next to the old soldered portion of the wire(s). Do not remove any more than is needed to attach the new diode. Diode Identification Step 4: Install New Diode Check current flow direction of the new diode, being sure to install the diode with correct bias. Refer the image for replacement diode symbols and current flow explanations. Attach the new diode to the wire(s) using 60/40 rosin core solder. Use a beat sink (aluminum alligator clip) attached across the diode wire ends to protect the diode from excess heat. Follow the manufacturer's instructions for the soldering equipment you are using. Step 5: Install Terminal(s) Install terminal(s) into the connector body if previously removed in Step 2. Step 6: Tape Diode to Harness Tape the diode to the harness or connector using electrical tape. To prevent shorts to ground and water intrusion, completely cover all exposed wire and diode attachment points. Acceptable Diode Replacements In the event 1 amp, 50 PIV (Peak Inverse Rating) diodes are unavailable, a universal diode with a 1 amp, 400 PIV rating can be used for the following applications: ^ A/C Compressor Clutch ^ ABS/4WAL (the ABS Diode on the Delco Moraine is hidden inside of an electrical connector under the carpet at the RH panel) ^ Wiper ^ Charging System (hidden in wire harness) ^ Parking Brake (vehicle with ABS) ^ Relays ^ Solenoids Locations Blower Motor Switch: Locations At heater control. Page 2374 Oil Pressure Gauge: Testing and Inspection Gauge Reads High 1. Disconnect lead from sensor, then turn ignition switch to the ON position and ground lead. 2. If gauge reads low, replace sensor. 3. If gauge reads high, locate and repair open circuit between sensor and gauge. Page 1681 Spark Plug Diagnosis Page 1198 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 2111 selection and verification, refer to your paint manufacturer's color book. On wheels that were previous clearcoated aluminum it is recommended that all four wheels and their center caps be refinished to maintain color uniformity. Important: THE PRODUCTS LISTED MUST BE USED AS A SYSTEM. DO NOT MIX OTHER MANUFACTURERS' PRODUCT LINES WITH THE REQUIRED MATERIALS. PRODUCTS LISTED IN THIS BULLETIN HAVE SHOWN THE REQUIRED REPAIR DURABILITY, AND CURRENTLY ARE THE ONLY PAINT SYSTEMS THAT MEET GM SPECIFICATION 4350M-A336. Procedures 1. Remove wheels from vehicle. Tires may remain mounted on wheels. 2. Remove balance weights and mark their location on tire. 3. Wipe excess grease, etc. from wheels with wax and grease remover. 4. Have wheels plastic media blasted to remove clearcoat. FOR FURTHER INFORMATION ON MEDIA BLASTING IN YOUR AREA, CALL US TECHNOLOGIES INC., CONTACT DAVE ROSENBURG AT 1-800-634-9185. Caution: IT IS MANDATORY THAT ADEQUATE RESPIRATORY PROTECTION BE WORN. EXAMPLES OF SUCH PROTECTION ARE: AIR LINE RESPIRATORS WITH FULL HOOD OR HALF MASK. IF NOT AVAILABLE, USE A VAPOR/PARTICULATE RESPIRATOR THAT RESPIRATOR MANUFACTURER RECOMMENDS AS EFFECTIVE FOR ISOCYANATE VAPOR AND MISTS (UNLESS LOCAL REGULATIONS PREVAIL). 5. Painting Process a. Refer to Attachments 1-3 for each System's individual formula and process. b. After following the specific System's individual formula and process, follow these steps: 6. Unmask wheels. 7. Clean all wheel mounting surface of any corrosion, overspray, or dirt. 8. Install new coated balance weights, at marked locations. 9. Replace wheels on vehicle. 10. USE A TORQUE STICK ON AN IMPACT WRENCH, OR A TORQUE WRENCH TO CONSISTENTLY AND UNIFORMLY FASTEN THE WHEEL TO THE SPECIFIED TORQUE FOR THE VEHICLE. THE STAR PATTERN MUST BE FOLLOWED. Important: TORQUE STICKS MUST BE USED ANY TIME AN IMPACT WRENCH IS USED TO TIGHTEN WHEEL NUTS. Warranty Information For vehicles repaired under warranty, use as shown. Attachment 1 - DuPont Products Page 1925 Convenience Center Page 255 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable With Manual Transmission Engine Control Module: Specifications With Manual Transmission PCM Connector Pin-Out Page 1839 Fluid - M/T: Fluid Type Specifications NV4500 Manual Transmission ............................................................................................................................. Castrol Syntorq GL-4 Transmission Fluid NV3500 Manual Transmission ......................................................................................................................................... Synchromesh Transmission Fluid Page 1324 Testing For Continuity Continuity Check Through A Switch 1. Remove the fuse to the circuit involved. 2. Connect one lead of a self-powered test light or ohmmeter to one end of the part of the circuit you wish to test. 3. Connect the other lead to the other end of the circuit. 4. If the self-powered test light glows, there is continuity. When using an ohmmeter, LO or no resistance means good continuity. Testing For Voltage Drop Voltage Drop Test This test checks for voltage being lost along a wire, or through a connection or switch. 1. Connect the positive lead of a Digital Voltmeter (DVM) to the end of the wire (or to one side of the connection or switch) which is closer to the Battery. 2. Connect the negative lead to the other end of the wire (or the other side of the connection or switch). 3. Operate the circuit. 4. The DVM will show the difference in voltage between the two points. Testing For Short to Ground Page 3468 The existing labor operation (E7200) has been changed to include "Add" conditions for cylinders that will not rotate. New Tumblers New tumblers are available from GMSPO for recoding lock cylinders that use double-sided reversible keys. These new tumblers should be used immediately and information about the disposition of original tumblers will be provided by GMSPO. Figure 1 shows the new tumbler profile. The shaded area was part of the original tumbler profile, and is removed on the new tumblers. The new part numbers for the tumblers are as follows: Part No. 2852732 = Tumbler # 1 Part No. 2852733 = Tumbler # 2 Part No. 2852734 = Tumbler # 3 Part No. 2852735 = Tumbler # 4 Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. New Procedures For Seized/Won't Rotate Column Mounted Ign. CYL. Page 1298 The existing labor operation (E7200) has been changed to include "Add" conditions for cylinders that will not rotate. New Tumblers New tumblers are available from GMSPO for recoding lock cylinders that use double-sided reversible keys. These new tumblers should be used immediately and information about the disposition of original tumblers will be provided by GMSPO. Figure 1 shows the new tumbler profile. The shaded area was part of the original tumbler profile, and is removed on the new tumblers. The new part numbers for the tumblers are as follows: Part No. 2852732 = Tumbler # 1 Part No. 2852733 = Tumbler # 2 Part No. 2852734 = Tumbler # 3 Part No. 2852735 = Tumbler # 4 Follow the procedures in the General Information Section of the appropriate vehicle Service Manual when recoding of cylinders is required. New Procedures For Seized/Won't Rotate Column Mounted Ign. CYL. Page 619 1. Remove push nail from upper forward area of door panel (Figure 1). 2. Place shim on push nail stem (Figure 2). 3. Install push nail on door panel. Parts Information P/N Description Qty 15730041 Shim, Gray 1 15730042 Shim, Navy Blue 1 15730043 Shim, Ruby Red 1 Shift Indicator Light Application and Operation Air Flow Meter/Sensor Relay: Technical Service Bulletins Shift Indicator Light Application and Operation File In Section: 7 - Transmission Bulletin No.: 36-72-07A Date: February, 1995 Subject: Manual Transmission Shift Indicator Light Application and Operation Models: 1993-95 Chevrolet and GMC Truck C/K and S/T Models with Manual Transmission This bulletin is being revised to add the 1995 model year. Please discard bulletin number 367207 (Group Reference - Transmission). Certain trucks are not equipped with a shift indicator light. The shift light is commonly used to achieve improved fuel economy by prompting the driver when to upshift. Depending on the engine/transmission installed in the vehicle, the shift light can have the following characteristics: ^ Indicates proper shift point for maximum fuel economy. ^ Indicates engine over-speed. ^ Shift light is inoperative. The following charts detail normal shift light operation: 1993 Models: Page 388 Fig.2-Symbols (Part 2 Of 3) Page 2846 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 509 Fig.2-Symbols (Part 2 Of 3) Page 917 Proper First Taping Step 6: Tape the Splice Center and roll the splicing tape. The tape should cover the entire splice. Roll on enough tape to duplicate the thickness of the insulation on the existing wires. Do not flag the tape. Flagged tape may not provide enough insulation, and the flagged ends will tangle with the other wires in the harness. Proper Second Taping If the wire does not belong in a conduit or other harness covering, tape the wire again. Use a winding motion to cover the first piece of tape. Splicing Twisted/Shielded Cable Page 316 Parts Information Important: In 1994, the L65 and L56 engines changed fuel injection pumps that required a new EPROM. The current fuel injection pump will service prior models. Be sure to match the EPROM with the proper engine fuel injection pump. Parts are currently available through GMSPO. Warranty Information For vehicles repaired under warranty, use the table. Page 2415 Idle Speed: Adjustments Minimum Idle Speed Adjustment 1. Check controlled idle speed and perform idle speed control system check first. 2. Set parking brake and block drive wheels. 3. Start engine and bring it to normal operating temperature 85°C-100°C (185°F-212°F). Turn engine "OFF." 4. Remove air cleaner, adapter and gaskets. Check that the throttle lever is not being bound by the throttle or cruise control cables. 5. With IAC valve connected, Connect Tech 1 and command IAC counts to 0. 6. With ignition "ON," engine stopped, disconnect IAC valve electrical connector. (This disables IAC valve in seated position.) Care should be taken to pull the connector straight out so that the moment of electrical disconnect is the same for all the pins. Otherwise the pintle may move as the connector is removed. 7. Start engine. With transmission in neutral, allow engine rpm to stabilize. Make sure that the ISC actuator is not contacting the throttle lever. If so refer to "IAC Actuator System Check." 8. Check rpm against specifications. Disregard IAC counts on Tech 1 scan tool with the IAC disconnected. If the engine has less than 500 miles or is checked at altitudes above 1500 feet, the idle rpm with a seated IAC valve should be lower than values above. 9. If the minimum idle speed is within specifications, no further check is required. 10. If the minimum idle speed is not within specifications, perform the following procedures: Idle Stop Screw 11. If present, remove stop screw plug by piercing it with an awl, then applying leverage. The screw is covered to discourage unauthorized adjustments. 12. With engine at normal operating temperature 85°C-100°C (185°F-212°F), adjust stop screw to obtain nominal rpm per specifications with seated IAC valve. 13. Turn ignition "OFF," and reconnect IAC valve electrical connector. 14. Disconnect Tech 1 scan tool or tachometer. 15. Use silicon sealant or equivalent to cover stop screw hole. 16. Install air cleaner and adapter. 17. Reset IAC valve. Refer to "Idle Air Control (IAC) System Check." Locations Electronic Brake Control Module: Locations The Electronic Brake Control Unit (EBCM) is mounted to the top of the Brake Pressure Modulator Valve (BPMV) and is housed in aluminum with a black plastic top. Page 892 Fig.2-Symbols (Part 2 Of 3) Page 3630 3. Replace the fuse. ^ If the fuse blows, the short is in the wiring leading to the first connector or switch. Use a test light or meter as described. ^ If fuse does not blow, refer to next step. 4. Close each connector or switch until the fuse blows in order to find which circuit has the short. Connect test lamp or meter at the connector to the suspect circuit (disconnected) rather than at the fuse terminals. Test Light/Digital Voltmeter Use a test light to check for voltage. A Test Light (J 34l42-B) is made up of a 12 volt light bulb with a pair of leads attached. After grounding one lead, touch the other lead to various points along the circuit where voltage should be present. When the bulb goes ON, there is voltage at the point being tested. A Digital Voltmeter (DVM) can be used instead of a test light. While a test light shows whether or not voltage is present, a DVM indicates how much voltage is present. An increasing number of circuits include solid state control modules. One example is the Engine Control Module (ECM). Voltages in these circuits should be tested only with a 10-megohm or higher impedance DVM or multimeter (J 39200). Unless directed to within the diagnostics, NEVER use a test light on circuits that contain solid state components, since damage to these components may result. When testing for voltage or continuity at the connection, it is not necessary to separate the two halves of the connector. Unless testing a Weather Pack(R) connector, always probe the connector from the back. Always check both sides of the connector. An accumulation of dirt and corrosion between contact surfaces is sometimes a cause of electrical problems. Refer to Procedures in checking terminal contact. See: General Troubleshooting Procedures/Checking Terminal Contacts Connector Test Adapters Connector Test Adapter Kit (J 35616-A) is available for making tests and measurements at separated connectors. This kit contains an assortment of probes which mate with many of the types of terminals you will see. Avoid using paper clips and other substitutes since they can damage terminals and cause incorrect measurements. Self-Powered Test Light A self-powered test light (J 21008-A) can be used to check for continuity. This tool is made up of a light bulb, Battery and two leads. If the leads are touched together, the bulb will go ON. A self-powered test light is used only on an unpowered circuit. First remove the fuse which feeds the circuit you're working on. Select two specific points along the circuit through which there should be continuity. Connect one lead of the self-powered test light to each point. If there is continuity, the test light circuit will be completed and the bulb will go ON. NEVER use a self-powered test light on circuits that contain solid state components, since damage to these components may result. Ohmmeter An ohmmeter can be used instead of a self-powered test light. The ohmmeter shows how much resistance there is between two points along a circuit. LO resistance means good continuity. Circuits which include any solid state control modules, such as the Engine Control Module (ECM), should be tested only with a 10-megohm or higher impedance digital multimeter (J 39200). When measuring resistance with a Digital Voltmeter (DVM), the vehicle Battery should be disconnected. This will prevent incorrect readings. DVMs apply such a small voltage to measure resistance that the presence of voltages can upset a resistance reading. Diodes and solid state components in a circuit can cause an ohmmeter to give a false reading. To find out if a component is affecting a measurement, take a reading once, reverse the leads and take a second reading. If the readings differ, the solid state component is affecting the measurement. Fused Jumper Wire A fused jumper (J 36169) is available with small clamp connectors providing adaptation to most connectors without damage. This fused jumper wire is supplied with a 20 amp fuse which may not be suitable for some circuits. Do not use a fuse with a higher rating than the fuse that protects the circuit being tested. NOTE: A fused jumper may not protect solid state components from being damaged. Short Finder Short Finders (J 8681-A) are available to locate hidden shorts to ground. The short finder creates a pulsing magnetic field in the shorted circuit and shows you the location of the short through body trim or sheet metal. Page 2178 condition, install the appropriate main bearings as determined by the following procedure. Calibration Information - 1992-93 LB4 VIN Z The revised PROMs reduce spark advance after the engine is started. The reduction in spark lowers the cylinder pressure and eliminates the knock. The revised PROMs will NOT eliminate a piston slap (Category C) or valve train noise (Category B) concern. The base cold knock PROM contains the previously released calibration updates. For 1992 LB4, the previous field release is included for torque converter clutch (TCC) lock up (see Bulletin 137107 - Chevrolet 92-75-7A; GMC Truck 92-7A-40; Oldsmobile 92-T-34; Canada 9274L60100) for automatic transmissions, or neutral gear rattle for manual transmissions (see Bulletin 267201R - Chevrolet 92-187B-7B; GMC Truck 92-7B-149A; Canada 93-7B-105). If a vehicle has had a detonation fix PROM installed previously, select the combined detonation and cold knock fix PROM for the application. See Bulletin 376508 for more information on field fix PROM for the application and detonation. Important: Use of a detonation fix PROM in a non-detonating vehicle may result in degraded driveability. GMSPO currently stocks three (3) PROMs for each light duty 1992 model year LB4 application. Base Cold Knock Fix Combination Cold Knock and Detonation Fix GMSPO Service Parts Assistance Center (SPAC 1-800-433-6961) will have information available on each PROM part number. Select the PROM from the table. Old Broadcast Code (Old B/C Code) and Scan I.D. information has been supplied to help installed previously. Use a TECH-1 to determine the Scan I.D. of the PROM in the vehicle or remove the PROM and read the Broadcast Code (B/C Code). If the B/C Code/Scan I.D. can be found in the first table, a detonation fix has not been installed. PROMs are currently available GMSPO. 1990-95 L05 VIN K Page 314 Page 97 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 958 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Starting - Revised Procedures for Inop Ignition Cylinder Technical Service Bulletin # 73-01-09 Date: 971001 Starting - Revised Procedures for Inop Ignition Cylinder File In Section: 0 - General Information Bulletin No.: 73-01-09 Date: October, 1997 INFORMATION Subject: New Tumblers for Cylinder Recoding, Revised Repair Procedures for Inoperative Ignition Cylinders (Seized/Won't Rotate), Labor Operation/Time Allowances Models: 1995-97 Buick Skylark, Riviera 1995-97 Chevrolet Cavalier 1997 Chevrolet Corvette, Malibu, Venture 1995-97 Oldsmobile Achieva 1997 Oldsmobile Aurora, Cutlass, Silhouette 1995-97 Pontiac Grand Am, Sunfire 1997 Pontiac Grand Prix, Trans Sport 1995-97 Chevrolet and GMC C/K, S/T Models 1996-97 Chevrolet and GMC G, M/L Vans 1996-97 Oldsmobile Bravada The information in this bulletin concerns new designed tumblers for recoding lock cylinders that use double sided reversible keys, revised procedures for servicing ignition lock cylinders that are seized or not able to rotate and revised labor time guide information and allowances. Parts Information Parts are currently available from GMSPO. Warranty Information Page 2944 Step 3: Strip the Insulation When replacing a wire, use a wire of the same size as the original wire or larger. The schematics list wire size in metric units. The table shows the commercial AWG wire sizes that can be used to replace each metric wire size. Each AWG size is either equal to or larger than the equivalent metric size. To find the correct wire size either find the wire on the schematic page and convert the metric size to the AWG size, or use an AWG wire gage. If you aren't sure of the wire size, start with the largest opening in the wire stripper and work down until a clean strip of the insulation is removed. Be careful to avoid nicking or cutting any of the wires. Entering The Splice Clip Step 4: Crimp the Wires Select the proper clip to secure the splice. To determine the proper clip size for the wire being spliced, follow the directions included in the J 38125-A Terminal Repair Kit. Select the correct anvil on the crimper. (On most crimpers your choice is limited to either a small or large anvil.) Overlap the stripped wire ends and hold them between your thumb and forefinger as shown. Then, center the splice clip under the stripped wires and hold it in place. ^ Open the crimping tool to its full width and rest one handle on a firm flat surface. ^ Center the back of the splice clip on the proper anvil and close the crimping tool to the point where the former touches the wings of the clip. Crimping The Splice Clip Page 597 Refrigerant Pressure Sensor / Switch: Service and Repair Removal and Installation If replacement of the pressure cycling switch is necessary, it is important to note that this may be done without removing the refrigerant charge. A service fitting is located in the pressure switch fitting. During replacement of the pressure switch. a new O-ring seal must be installed and the switch assembled to 4.5 Nm (40 lb in.). Page 3721 Twisted/shielded Cable Twisted/shielded cable is sometimes used to protect wiring from electrical noise (stray signals). For example, two-conductor cable of this construction is used between the Engine Control Module (ECM) and the distributor. Step 1: Remove Outer Jacket Remove the outer jacket and discard it. Be careful to avoid cutting into the drain wire or the mylar tape. Step 2: Unwrap the Tape Unwrap the aluminium/mylar tape, but do not remove it. The tape will be used to rewrap the twisted conductors after the splices have been made. The Untwisted Conductors Step 3: Prepare the Splice Untwist the conductors. Then, prepare the splice by following the splicing instructions for copper wire presented earlier. Remember to stagger splices to avoid shorts. Step 4: Re-assemble the Cable After you have spliced and taped each wire, rewrap the conductors with the mylar tape. Be careful to avoid wrapping the drain wire in the tape. The Re-assembled Cable Next, splice the drain wire following the splicing instructions for copper wire. Then, wrap the drain wire around the conductors and mylar tape. Page 1070 Electronic 4-Speed Automatic Overdrive Transmission Page 1873 P/N 1050436) to prevent false diagnosis at a later point. * We believe this source and their equipment to be reliable. There may be additional manufacturers of such equipment. General Motors does not endorse, indicate any preference for or assume any responsibility for the products or equipment from these firms or for any such items which may be available from other sources. Parts Information GM solvent, P/N 1050436, is currently available from GMSPO. Page 300 Page 3167 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 2890 Typical Pull-to-seat Connector And Terminal Follow the steps below to repair Push-to-Seat or Pull-to-Seat connectors. The steps are illustrated with typical connectors. Your connector may differ, but the repair steps are similar. Some connectors do not require all the steps shown. Skip those that don't apply. Step 1: Remove any Connector Position Assurance (CPA) Locks . CPAs are designed to retain connectors when mated. Step 2: Remove any Terminal Position Assurance (TPA) Locks. TPAs are designed to keep the terminal from backing out of the connector. NOTE: The TPA must be removed prior to terminal removal and must be replaced when the terminal is repaired and reseated. Step 3: Open any secondary locks. A secondary lock aids in terminal retention and is usually molded to the connector. Step 4: Separate the connector halves and back out seals. Step 5: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 6: Locate the terminal lock tang in the connector canal. Step 7: Insert the proper size pick (refer to Terminal Repair kit J 38125-A) straight into the connector canal at the mating end of the connector. Step 8: Depress the locking tang to unseat the terminal. ^ Push-to-Seat - Gently pull on the lead to remove the terminal through the back of the connector. ^ Pull-to-Seat - Gently push on the lead to remove the terminal through the front of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 9: Inspect terminal and connector for damage. Repair as necessary (refer to Terminal Repairs). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 10: Reform lock tang and reseat terminal in connector body. Apply grease if connector was originally equipped with grease. Step 11: Install any CPAs or TPAs, close any secondary locks and join connector halves. Weather Pack(R) Connectors Page 2994 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Page 2891 Typical Weather Pack(R) Connector And Terminal Follow the steps below to repair Weather Pack(R) connectors. Step 1: Separate the connector halves. Step 2: Open secondary lock. A secondary lock aids in terminal retention and is usually molded to the connector. Step 3: Grasp the lead and push the terminal to the forward most position. Hold the lead at this position. Step 4: Insert the Weather Pack(R) terminal removal tool into the front (mating end) of the connector cavity until it rests on the cavity shoulder. Step 5: Gently pull on the lead to remove the terminal through the back of the connector. NOTE: NEVER use force to remove a terminal from a connector. Step 6: Inspect the terminal and connector for damage. Repair as necessary (refer to Terminal Repair). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Terminal Repairs Step 7: Re-form the lock tang and reseat terminal in connector body. Step 8: Close secondary locks and join connector halves. Repairing Short Circuits Caused By Damaged Wire Insulation ^ Locate the damaged wire. ^ Find and correct the cause of the wire insulation damage. ^ For minor damage, tape over the wire. If damage is more extensive, replace the faulty segment of the wire (refer to the Splicing Instructions for copper or shielded cable for the correct splicing procedure). See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Splice Clips See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Copper Wire Using Crimp and Seal Splice Sleeves See: Wire Repair Procedures/Typical Electrical Repair Procedures/Splicing Twisted/Shielded Cable Splicing Copper Wire Using Crimp and Seal Splice Sleeves Crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial to form a one-to-one splice. They are to be used where there are special requirements such as moisture sealing. Crimp and seal splice sleeves are included in the J 38125-A Terminal Repair Kit. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). The crimp and seal splice sleeves may be used on all types of insulation except Tefzel and coaxial and may only be used to form a one-to-one splice. Page 693 Throttle Body Injection (Part 7 Of 7) Page 1436 Brake Switch - TCC: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical Page 1487 Testing For Short With Self Powered Test Light Or Ohmmeter WITH A TEST LIGHT OR DIGITAL VOLTMETER (DVM) 1. Remove the blown fuse and disconnect the load. 2. Connect a test light or voltmeter across the fuse terminals (be sure that the fuse is powered). 3. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the test light or DVM. 4. When the test light glows, or the DVM registers, there is a short to ground in the wiring near that point. Testing For Short With Test Light Or DVM WITH A SELF-POWERED TEST LIGHT OR OHMMETER. 1. Remove the blown fuse and disconnect the Battery and load. 2. Connect one lead of a self-powered test light or ohmmeter to the fuse terminal on the load side. 3. Connect the other lead to a known good ground. 4. Beginning near the Fuse Block, wiggle the harness from side to side. Continue this at convenient points (about 6 inches apart) while watching the self-powered test light or ohmmeter. 5. When the self-powered test light glows, or the ohmmeter registers, there is a short to ground in the wiring near that point. FUSES POWERING SEVERAL LOADS 1. Find the schematic under "Fuse Block Details," for the fuse that has blown. 2. Open the first connector or switch leading from the fuse to each load. Page 3843 Seal Splice Sequence The sleeve has a stop in the middle of the barrel to prevent the wire from going further. Close the hand crimper handles slightly to hold the splice sleeve firmly in the proper nest. Step 5: Insert Wires into Splice Sleeve and Crimp Insert the wire into the splice sleeve until it hits the barrel stop and close the handles of the J 38125-8 crimper tightly until the crimper handles open when released. The crimper handles will not open until the proper amount of pressure is applied to the splice sleeve. Repeat steps 4 and 5 for opposite end of the splice. Step 6: Shrink the Insulation Around the Splice Using the Ultratorch J 38125-5 (follow instructions that accompany Ultratorch), apply heat where the barrel is crimped. Gradually move the heat barrel to the open end of the tubing, shrinking the tubing completely as the heat is moved along the insulation. A small amount of sealant will come out of the end of the tubing when sufficient shrinking is achieved. Splicing Copper Wire Using Splice Clips Splice clips are included in the J 38125-A Terminal Repair Kit. The splice clip is a general purpose wire repair device. It may not be acceptable for applications having special requirements such as moisture sealing. Step 1: Open the Harness If the harness is taped, remove the tape. To avoid wire insulation damage, use a sewing "seam ripper" to cut open the harness (available from sewing supply stores). If the harness has a black plastic conduit, simply pull out the desired wire. Step 2: Cut the Wire Begin by cutting as little wire off the harness as possible. You may need the extra length of the wire later if you decide to cut more wire off to change the location of a splice. You may have to adjust splice locations to make certain that each splice is at least 40 mm (1.5 in.) away from other splices, harness branches or connectors. Wire Size Conversion Table Page 3500 force to separate the terminals. 4. Using an equivalent female terminal from the Terminal Repair Kit, J 38125-A, compare the retention force of this terminal to the female terminal in question by joining and separating the male terminal to the good female terminal, and then joining and separating the male terminal to the female terminal in question. If the retention force is significantly different between the two female terminals, replace the female terminal in question (refer to Terminal Repair Kit, J 38125-A). If a visual (physical) check does not reveal the cause of the problem, the vehicle may be able to be driven with a Digital Voltmeter (DVM) connected to the suspected circuit. An abnormal voltage reading when the problem occurs indicates the problem may be in that circuit. Detecting Electrical Intermittents PROCEDURE Use the following procedure to detect intermittent terminal contact or a broken wire with an intermittent connection inside the insulation. The J 39200 Digital Multimeter has the ability to monitor current, resistance, or voltage while recording the minimum (MIN) and maximum (MAX) values measured. The meter can also be set to display the average (AVG) value measured. When diagnosing circuits that have voltage applied, use the voltage setting to monitor a connector (or length of a circuit) which is suspected of having an intermittent connection but is currently operating normally. 1. Connect the J 39200 Digital Multimeter to both sides of a suspect connector (still connected) or from one end of a suspect circuit to the other. This will continuously monitor the terminal contacts or length of wire being checked. Refer Meter Connections for examples of the various methods for connecting the meter to the circuit. See: General Troubleshooting Procedures/Meter Connections 2. Set the meter for voltage. Since the "MIN MAX" mode does not use auto ranging, manually select the voltage range necessary before proceeding. 3. Press the "MIN MAX" button. The meter should read "100 ms RECORD" (100 millisecond record) and emit a 1/4 second beep. The meter is now ready to record and will generate an audible tone for any change in voltage. At this point, you may wish to press the "PEAK MIN MAX" button, which will record any voltage variations that occur for at least 1 millisecond. 4. Try to simulate the condition that is potentially causing an intermittent connection, either by wiggling connections or wiring, test driving or performing other operations. If an open or resistance is created, a voltage will be present and the meter will emit a tone for as long as the open or resistance exists. Any change in voltage will cause the meter to emit a tone for no less than 1/4 second. (Listening for a tone while manipulating wiring is very helpful for narrowing down an intermittent connection.) Use the MIN and MAX values when the meter is out of sight or sound range, in noisy areas or for test driving when it may not be possible to monitor the meter. To check the MIN and MAX recorded voltages press "MIN MAX" once for MAX and twice for MIN. A variation between MIN and MAX recorded voltages (unless nearly 0 volts) suggests an intermittent open or that resistance exists and should be repaired as necessary. IMPORTANT: The "100 ms RECORD" (100 millisecond record) mode is NOT the amount of time allowed to perform a specific procedure. It is the amount of time used to record each snapshot of information used for calculating "AVG" when in the "MIN MAX" mode. Intermittents and Poor Connections Most intermittents are caused by faulty electrical connections or wiring, although occasionally a sticking relay or solenoid can be a problem. Some items to check are: ^ Poor mating of connector halves, or terminals not fully seated in the connector body (backed out). ^ Dirt or corrosion on the terminals. The terminals must be clean and free of any foreign material which could impede proper terminal contact. ^ Damaged connector body, exposing the terminals to moisture and dirt, as well as not maintaining proper terminal orientation with the component or mating connector. ^ Improperly formed or damaged terminals. All connector terminals in problem circuits should be checked carefully to ensure good contact tension. Use a corresponding mating terminal to check for proper tension. Refer to Checking Terminal Contact for the specific procedure. ^ The J 35616-A Connector Test Adapter Kit must be used whenever a diagnostic procedure requests checking or probing a terminal. Using the adapter will ensure that no damage to the terminal will occur, as well as giving an idea of whether contact tension is sufficient. If contact tension seems incorrect, refer to Checking Terminal Contact. See: General Troubleshooting Procedures/Checking Terminal Contacts ^ Poor terminal-to-wire connection. Some conditions which fall under this description are poor crimps, poor solder joints, crimping over wire insulation rather than the wire itself, corrosion in the wire-to-terminal contact area, etc. ^ Wire insulation which is rubbed through, causing an intermittent short as the bare area touches other wiring or parts of the vehicle. ^ Wiring broken inside the insulation. This condition could cause a continuity check to show a good circuit, but if only 1 or 2 strands of a multi-strand type wire are intact, resistance could be far too HI. To avoid any of the above problems when making wiring or terminal repairs, always follow the instructions for wiring and terminal repair outlined under the Repair Procedures. See: Diagrams/Diagnostic Aids/Wire Repair Procedures Meter Connections The previous diagnostic procedure was written to detect intermittents using the meter set to voltage. Whether using the current, voltage or resistance Page 3100 Knock Sensor: Testing and Inspection Knock Sensor Check Page 1480 Single Wire Feed Fusible Link To replace a damaged fusible link, cut it off beyond the splice. Replace with a repair link. When connecting the repair link, strip wire and use staking-type pliers to crimp the splice securely in two places. For more details on splicing procedures, refer to "Typical Electrical Repair Procedures." Use crimp and seal splices whenever possible. See: Wire Repair Procedures/Typical Electrical Repair Procedures Double Wire Feed Fusible Link To replace a damaged fusible link which feeds two harness wires, cut them both off beyond the splice. Use two repair links, one spliced to each harness wire. Additional Information NOTE: Turn OFF power to the test circuit before attempting in-circuit resistance measurements to prevent false readings or damage to the meter. Do not use the meter to measure resistance through a solid state module. Continuity tests that work well for detecting intermittent shorts to ground can be performed by setting the meter to "ohms" then pressing the "PEAK MIN MAX" button. An audible tone will be heard whenever the meter detects continuity for at least 1 millisecond. The J 39200 Instruction Manual is a good source of information and should be read thoroughly upon receipt of the meter as well as kept on hand for reference during new procedures. Basic Knowledge Required Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in this section. You should understand the basic theory of electricity and know the meaning of voltage, current (amps) and resistance (ohms). You should understand what happens in a circuit with an open or a shorted wire. You should be able to read and understand a wiring diagram. The following four-step troubleshooting procedure is recommended: Step 1: Check the Problem Perform a System Check to determine a symptom. Don't waste time fixing part of the problem! Do not begin disassembly or testing until you have narrowed down the possible causes. Step 2: Read the Electrical Schematic Study the schematic. Read the Circuit Operation text if you do not understand how the circuit should work. Check circuits that share wiring with the problem circuit. (Shared circuits are shown on Power Distribution, Ground Distribution, Fuse Block Details and Light Switch Details.) Try to operate the shared circuits. If the shared circuits work, then the shared wiring is OK. The cause must be within the wiring used only by the problem circuit. If several circuits fail at the same time, chances are the power (fuse) or ground circuit is faulty. Step 3: Find the fault and repair ^ Narrow down the possible causes. ^ Use the Troubleshooting Hints. ^ Make the necessary measurements or checks as given in the System Diagnosis. Page 1181 Wire Color Code Identification Black: BLK Blue: BLU Brown: BRN Grey: GR Or GRY Green: GRN Natural: NAT Orange: ORN Pink: PNK Purple: PPL Red: RED Tan: TAN White: WHT Yellow: YEL Dark: DK (example: DK GRN same as Dark Green) Light: LT (example: LT BLU same as Light Blue) Wire Size Conversion Table Page 372 Notice: Cut through plastic case material only. Aluminum tubes are located approximately 1/8" behind the case wall (Figure 2, view 1). Do not use a larger diameter cutting wheel. 15. Using a heat gun to soften the plastic case, pull back the access door on the upper evaporator case carefully to prevent breaking the case. Reach in carefully and remove the holding clamp securing the capillary tube to the evaporator outlet tube. Be careful not to damage the capillary tube. Discard clamp. 16. Using a heat gun to soften the plastic case, pull back the access door on the lower evaporator case carefully to prevent breaking the case (Figure 2). Reach in carefully with two small adjustable wrenches and loosen the fitting attaching the TXV to the evaporator inlet tube. It will require a 7/8" crows foot extension to loosen the TXV outlet joint fitting hidden behind the TXV itself. Remove and discard the TXV. 17. Remove original O-rings from the evaporator tubes and replace with new O-rings that have been oiled with 525 viscosity refrigerant mineral oil. DO NOT USE PAG LUBRICANT. 18. Install the new TXV to the evaporator tubes being careful not to damage the O-rings. Finger tighten the joints and then torque the joints, using a backup wrench to hold the TXV in position to: INLET 20-35 Nm (14-25 lb.ft.) OUTLET 15-22 Nm (11-16 lb.ft.) Page 2814 PCM Connector Pin-Out Page 2823 Fig.3-Symbols (Part 3 Of 3) Vacuum Motors operate like electrical solenoids, mechanically pushing or pulling a shaft between two fixed positions. When vacuum is applied, the shaft is pulled in. When no vacuum is applied, the shaft is pushed all the way out by a spring. Double Diaphragm Motors can be operated by vacuum in two directions. When there is no vacuum, the motor is in the center "at rest" position. Some Vacuum Motors such as the Servo Motor in the Cruise Control can position the actuating arm at any position between fully extended and fully retracted. The servo is operated by a control valve that applies varying amounts of vacuum to the motor. The higher the vacuum level, the greater the retraction of the motor arm. Servo Motors work like the two position motors; the only difference is in the way the vacuum is applied. Servo Motors are generally larger and provide a calibrated control. Supplemental Inflatable Restraint (SIR) System SIR Symbol The Supplemental Inflatable Restraint (SIR) symbol is used on schematics to alert the technician to the following important caution. CAUTION: This vehicle is equipped with SIR. Refer to CAUTIONS in SIR under Air Bags and Seat Belts before performing service on or around SIR components or wiring. Failure to follow CAUTIONS could result in possible air bag deployment, personal injury, or otherwise unneeded SIR system repairs. Wheels/Tires - Refinishing Aluminum Wheels Wheels: All Technical Service Bulletins Wheels/Tires - Refinishing Aluminum Wheels INFORMATION Bulletin No.: 99-08-51-007E Date: March 17, 2011 Subject: Refinishing Aluminum Wheels Models: 2012 and Prior GM Passenger Cars and Trucks Supercede: This bulletin is being revised to add additional model years. Please discard Corporate Bulletin Number 99-08-51-007D (Section 08 - Body and Accessories). This bulletin updates General Motor's position on refinishing aluminum wheels. GM does not endorse any repairs that involve welding, bending, straightening or re-machining. Only cosmetic refinishing of the wheel's coatings, using recommended procedures, is allowed. Evaluating Damage In evaluating damage, it is the GM Dealer's responsibility to inspect the wheel for corrosion, scrapes, gouges, etc. The Dealer must insure that such damage is not deeper than what can be sanded or polished off. The wheel must be inspected for cracks. If cracks are found, discard the wheel. Any wheels with bent rim flanges must not be repaired or refinished. Wheels that have been refinished by an outside company must be returned to the same vehicle. The Dealer must record the wheel ID stamp or the cast date on the wheel in order to assure this requirement. Refer to Refinisher's Responsibility - Outside Company later in this bulletin. Aluminum Wheel Refinishing Recommendations - Chrome-plated aluminum wheels Re-plating these wheels is not recommended. - Polished aluminum wheels These wheels have a polyester or acrylic clearcoat on them. If the clearcoat is damaged, refinishing is possible. However, the required refinishing process cannot be performed in the dealer environment. Refer to Refinisher's Responsibility - Outside Company later in this bulletin. - Painted aluminum wheels These wheels are painted using a primer, color coat, and clearcoat procedure. If the paint is damaged, refinishing is possible. As with polished wheels, all original coatings must be removed first. Media blasting is recommended. Refer to GM Aluminum Refinishing Bulletin #53-17-03A for the re-painting of this type of wheel. - Bright, machined aluminum wheels These wheels have a polyester or acrylic clearcoat on them. In some cases, the recessed "pocket" areas of the wheel may be painted. Surface refinishing is possible. The wheel must be totally stripped by media blasting or other suitable means. The wheel should be resurfaced by using a sanding process rather than a machining process. This allows the least amount of material to be removed. Important Do not use any re-machining process that removes aluminum. This could affect the dimensions and function of the wheel. Painting is an option to re-clearcoating polished and bright machined aluminum wheels. Paint will better mask any surface imperfections and is somewhat more durable than clearcoat alone. GM recommends using Corsican SILVER WAEQ9283 for a fine "aluminum-like" look or Sparkle SILVER WA9967 for a very bright look. As an option, the body color may also be used. When using any of the painting options, it is recommended that all four wheels be refinished in order to maintain color uniformity. Refer to GM Aluminum Refinishing Bulletin #53-17-03A for specific procedures and product recommendations. Refinisher's Responsibility - Outside Company Important Some outside companies are offering wheel refinishing services. Such refinished wheels will be permanently marked by the refinisher and are warranted by the refinisher. Any process that re-machines or otherwise re-manufactures the wheel should not be used. A refinisher's responsibility includes inspecting for cracks using the Zyglo system or the equivalent. Any cracked wheels must not be refinished. No welding, hammering or reforming of any kind is allowed. The wheel ID must be recorded and follow the wheel throughout the process in order to assure that the same wheel is returned. A plastic media blast may be used for clean up of the wheel. Hand and/or lathe sanding of the machined surface and the wheel window is allowed. Material removal, though, must be kept to a minimum. Re-machining of the wheel is not allowed. Paint and/or clear coat must not be present on the following surfaces: the nut chamfers, the wheel mounting surfaces and the wheel pilot hole. The refinisher must permanently ID stamp the wheel and warrant the painted/clearcoated surfaces for a minimum of one year or the remainder of the new vehicle warranty, whichever is Page 542 ESD Symbol Typical Schematic The ESD symbol is used on schematics to indicate which components are ESD sensitive. When handling any electronic part, the service technician should follow the guidelines below to reduce any possible electrostatic charge build-up on the service technician's body and inadvertent discharge to the electronic part. If it is not known whether or not a component is ESD sensitive, assume it is susceptible. Handling Procedures 1. Always touch a known good ground before handling the part. This should be repeated while handling the pan and more frequently after sliding across a seat, sitting down from a standing position or walking a distance. 2. Avoid touching electrical terminals of the part, unless so instructed by a written diagnostic procedure. 3. When using a voltmeter, be sure to connect the ground lead first. 4. Do not remove a part from its protective package until it is time to install the part. 5. Before removing the part from its package, ground the package to a known good ground on the vehicle. Measuring Procedures The circuits shown within the boxes are greatly simplified. Do not troubleshoot by measuring resistance at any terminal of these devices unless so instructed by a written diagnostic procedure. Due to the simplification of the schematics, resistance measurements could be misleading, or could lead to electrostatic discharge. Schematic Symbols Page 3336 ^ Make sure that the clip and wires are still in the correct position. Then, apply steady pressure until the crimping tool closes. ^ Before crimping the ends of the clip, be sure that: The wires extend beyond the clip in each direction. - No strands of wire are cut loose. - No insulation is caught under the clip. Completing The Crimp Crimp the splice again, once on each end. Do not let the crimping tool extend beyond the edge of the clip or you may damage or nick the wires. Applying The Solder Step 5: Solder Apply 60/40 rosin core solder to the opening in the back of the clip. Follow the manufacturer's instruction for the solder equipment you are using. Page 2493 Valve Clearance: Specifications Valve Arrangement FRONT TO REAR 7.4L/V8-454 ......................................................................................................................................... ........................................................... E-I-E-I-E-I-E-I Page 3315 Air Flow Meter/Sensor: Diagnostic Aids General Information The purpose of circuit protection is to protect the wiring assembly during normal and overload conditions. An overload is defined as a current requirement that is higher than normal. This overload could be caused by a short circuit or system malfunction. The short circuit could be the result of a pinched or cut wire or an internal device short circuit, such as an electronic module failure. The circuit protection device is only applied to protect the wiring assembly, and not the electrical load at the end of the assembly. For example, if an electronic component short circuits, the circuit protection device will assure a minimal amount of damage to the wiring assembly. However, it will not necessarily prevent damage to the component. There are three basic types of circuit protection devices: Circuit Breaker, Fuse and Fusible Link. Circuit Breakers A circuit breaker is a protective device designed to open the circuit when a current load is in excess of rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current will open the circuit between the circuit breaker terminals. There are two basic types of circuit breakers used in GM vehicles: cycling and non-cycling. Cycling Circuit Breaker The cycling breaker will open due to heat generated when excessive current passes through it for a period of time. Once the circuit breaker cools, it will close again after a few seconds. If the cause of the HI current is still present it will open again. It will continue to cycle open and closed until the condition causing the HI current is removed. Non-Cycling Circuit Breaker There are two types of non-cycling circuit breakers. One type is mechanical and is nearly the same as a cycling breaker. The difference is a small heater wire within the non-cycling circuit breaker. This wire provides enough heat to keep the bimetallic element open until the current source is removed. The other type is solid state, called out in this section as Electronic Circuit Breaker (ECB). This device has a Positive Temperature Coefficient. It increases its resistance greatly when excessive current passes through it. The excessive current heats the ECB. As it heats, its resistance increases, therefore having a Positive Temperature Coefficient. Eventually the resistance gets so HI that the circuit is effectively open. The ECB will not reset until the circuit is opened, removing voltage from its terminals. Once voltage is removed, the circuit breaker will re-close within a second or two. Fuses Fuse Devices The most common method of automotive wiring circuit protection is the fuse. A fuse is a device that, by the melting of its element, opens an electrical