Intermittent
Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
Backup Lamps Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the backup lamps are always on. Do the backup lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Use the scan tool to check if there are any codes set in the current or history Powertrain DTC Information. Are any codes present? | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | Go to Step 4 |
| 4 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
| 5 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | |
| 6 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Backup Lamps Always On
Backup Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the backup lamps are inoperative. Do the backup lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Is only one backup lamp inoperative? | Go to Step 5 | Go to Step 4 |
| 4 | Use the scan tool to check if there are any codes set in the current or history Powertrain DTC Information. Are any codes present? | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information | Go to Step 6 |
| 5 | Test the backup lamp supply voltage and ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 9 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
| 7 | Replace the affected backup lamp bulb or printed circuit board. Refer to Backup Lamp Bulb Replacement (GMC) or Tail Lamp Circuit Board Replacement . Did you complete the replacement? | Go to Step 9 | |
| 8 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | |
| 9 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Backup Lamps Inoperative
Clearance Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the clearance lamps are inoperative. Do the clearance lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Is the right tail lamp inoperative also? | Go to Step 5 | Go to Step 4 |
| 4 | Inspect the inoperative bulbs/sockets for open filaments or poor terminal contact. Does any lamp have an open filament or poor terminal contact? | Go to Step 7 | Go to Step 6 |
| 5 | Repair one of the following conditions. The short to ground in the clearance lamps supply voltage circuit or right tail lamp supply voltage circuit. The open in the clearance lamps supply voltage and right tail lamp supply voltage circuits. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | |
| 6 | Repair the open or high resistance in the clearance lamps supply voltage circuit or ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | |
| 7 | Replace the inoperative bulb or repair/replace the socket. Refer to Clearance Lamp Replacement or Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | |
| 8 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Clearance Lamps Inoperative
Cornering Lamps Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Turn ON the ignition, with the engine OFF. Turn the park lamps ON. Activate the turn signal switch in both directions to illuminate the cornering lamps. Did the cornering lamps operate properly? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Do the front parking lamps operate properly? | Go to Step 4 | Go to Symptoms - Lighting Systems |
| 4 | Test for a short to positive voltage in the cornering lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 6 | Go to Step 5 |
| 5 | Replace the multifunction turn signal switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | Go to Step 6 | |
| 6 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
Cornering Lamps Always On
Cornering Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Turn ON the ignition, with the engine OFF. Turn the park lamps ON. Activate the turn signal switch in both directions to illuminate the cornering lamps. Did the cornering lamps operate properly? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Do the front park lamps operate properly? | Go to Step 4 | Go to Symptoms - Lighting Systems |
| 4 | Disconnect the inoperative cornering lamp bulb. Turn ON the ignition, with the engine OFF. Turn On the inoperative cornering lamp. Connect a test lamp between the inoperative cornering lamp supply voltage circuit and the inoperative cornering lamp ground circuit. Did the test lamp illuminate? | Go to Step 8 | Go to Step 5 |
| 5 | Test the inoperative cornering lamp supply voltage supply circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 6 |
| 6 | Test the inoperative cornering lamp ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 7 |
| 7 | Test the turn signal switch front park lamps supply voltage circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 9 |
| 8 | Inspect for poor connections at the inoperative cornering lamp bulb connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 10 |
| 9 | Inspect for poor connections at the turn signal switch connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 11 |
| 10 | Replace the inoperative cornering lamp bulb. Refer to Cornering Lamp Bulb Replacement (Rainier) or Cornering Lamp Bulb Replacement (Envoy, Envoy XUV) . Did you complete the replacement? | Go to Step 12 | |
| 11 | Replace the turn signal switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the replacement? | Go to Step 12 | |
| 12 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 2 |
Cornering Lamps Inoperative
Courtesy Lamps Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Interior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views , Computer/Integrating Systems Connector End Views , or Power Door Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Verify that the courtesy/dome lamps are always ON. Do the courtesy/dome lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
| 3 | Inspect the following modules for the proper applicable data parameters included in the list below: Body Control Module (BCM) Driver Door Module (DDM) Passenger Door Module (PDM) Liftgate Module (LGM) Endgate Module (EGM) Refer to Scan Tool Data List and Scan Tool Data Definitions for typical values and definitions: The courtesy lamp switch The interior lamp defeat switch The door ajar switches The liftglass ajar switch The liftgate ajar switch The upper left dome lamp switch Was a problem found? | Go to Step 4 | Go to Step 8 |
| 4 | Disconnect and test the switch of the affected input circuit for proper continuity in the open and closed positions. Refer to Circuit Testing . Is continuity present? | Go to Step 5 | Go to Step 6 |
| 5 | Test the signal and ground circuits of the affected input circuit for the following: A short to ground An open A high resistance Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the affected switch. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 9 |
| 7 | Inspect for poor connections at the harness connector of the module in the affected circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 10 |
| 8 | Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 12 | Go to Step 11 |
| 9 | Replace the switch in the affected circuit. Refer to one of the following replacement procedures as applicable: Headlamp Switch Replacement Latch Replacement - Front Door Latch Replacement - Rear Door Latch Replacement - Liftgate Window Latch Replacement - Liftgate Latch Replacement - Endgate Left Upper Did you complete the replacement? | Go to Step 12 | |
| 10 | Replace the module in the affected circuit. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 12 | |
| 11 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 12 | |
| 12 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Courtesy Lamps Always On
Courtesy Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Interior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views , Computer/Integrating Systems Connector End Views , Power Door Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Verify that the courtesy/dome lamps are inoperative. Do the courtesy/dome lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
| 3 | Is only one lamp inoperative? | Go to Step 4 | Go to Step 5 |
| 4 | Test the voltage supply and ground circuits of the inoperative lamp for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 15 | Go to Step 13 |
| 5 | Inspect the following modules for the proper applicable data parameters included in the list below: Body Control Module (BCM) Driver Door Module (DDM) Passenger Door Module (PDM) Liftgate Module (LGM) Endgate Module (EGM) Refer to Scan Tool Data List and Scan Tool Data Definitions for typical values and definitions: The courtesy lamp switch The interior lamp defeat switch The door ajar switches The liftglass ajar switch The liftgate ajar switch The upper left dome lamp switch Was a problem found? | Go to Step 6 | Go to Step 10 |
| 6 | Disconnect and test the switch of the affected input circuit for proper continuity in the open and closed positions. Refer to Circuit Testing . Is continuity present? | Go to Step 7 | Go to Step 8 |
| 7 | Test the signal and ground circuits of the affected input circuit for the following: A short to ground An open A high resistance Refer to Circuit Testing and Wiring Repairs Did you find and correct the condition? | Go to Step 15 | Go to Step 9 |
| 8 | Inspect for poor connections at the harness connector of the affected switch. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 15 | Go to Step 11 |
| 9 | Inspect for poor connections at the harness connector of the module in the affected circuit. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 15 | Go to Step 12 |
| 10 | Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 15 | Go to Step 14 |
| 11 | Replace the switch in the affected circuit. Refer to one of the following replacement procedures as applicable: Headlamp Switch Replacement Latch Replacement - Front Door Latch Replacement - Rear Door Latch Replacement - Liftgate Window Latch Replacement - Liftgate Latch Replacement - Endgate Left Upper Did you complete the replacement? | Go to Step 15 | |
| 12 | Replace the module in the affected circuit. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 15 | |
| 13 | Replace the inoperative bulb. Did you complete the repair? | Go to Step 15 | |
| 14 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 15 | |
| 15 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Courtesy Lamps Inoperative
Daytime Running Lamps (DRL) Defeat Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the daytime running lamps (DRL) defeat feature of the headlamp switch operates properly. Do the DRL headlamps turn OFF when the defeat mode is applied? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Ensure that the automatic headlamps are in the DRL mode. Disconnect the headlamp switch. Momentarily connect a fused jumper wire between the DRL defeat switch signal circuit and the ground circuit of the headlamp switch instrument panel (I/P) harness connector. Do the DRL turn OFF or ON? | Go to Step 6 | Go to Step 4 |
| 4 | Test for an open, high resistance, short to ground, or short to voltage in the DRL defeat switch signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 9 | Go to Step 5 |
| 5 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
| 7 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | |
| 8 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the replacement? | Go to Step 9 | |
| 9 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Daytime Running Lamps (DRL) Defeat Inoperative
Daytime Running Lamps (DRL) Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the daytime running lamps (DRL) are inoperative. Do the DRL operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Do the low beam headlamps operate normally? | Go to Step 4 | Go to Symptoms - Lighting Systems |
| 4 | Ensure that the park brake is not SET. Install a scan tool. Turn ON the ignition, with the engine OFF. With a scan tool, observe the Park Brake Switch parameter in the body control module (BCM) data list. Does the scan tool display RELEASED? | Go to Step 6 | Go to Step 5 |
| 5 | Test the signal circuit of the park brake switch for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 12 | Go to Step 8 |
| 6 | Remove the headlamp driver module (HDM). Install a test lamp between the headlamp driver module connector battery positive voltage circuit terminal and the headlamp driver module control circuit terminal. Refer to Circuit Testing in Wiring Systems. Use the scan tool to command the DRL ON while observing the test lamp. Does the test lamp illuminate at slightly less than full intensity? | Go to Step 11 | Go to Step 7 |
| 7 | Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 9 |
| 8 | Inspect for poor connections at the harness connector of the park brake switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 10 |
| 9 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 12 | |
| 10 | Replace the park brake switch. Refer to Park Brake Warning Lamp Switch Replacement in Park Brake. Did you complete the replacement? | Go to Step 12 | |
| 11 | Replace the HDM. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the replacement? | Go to Step 12 | |
| 12 | Use the scan tool in order to clear any induced DTCs. Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Daytime Running Lamps (DRL) Inoperative
Daytime Running Lamps (DRL) On with Park Brake Applied
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views , Computer/Integrating Systems Connector End Views in Computer/Integrating Systems, or Hydraulic Brakes Connector End Views in Hydraulic Brakes | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the daytime running lamps (DRL) headlamps are on with the parking brake applied. Do the DRL headlamps operate normally with the parking brake applied? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Set the park brake. Turn the ignition ON with the engine OFF. With the scan tool, read the park brake switch status. Does the scan tool display SET? | Go to Step 6 | Go to Step 4 |
| 4 | Disconnect the park brake switch. Connect a fused jumper wire between the park brake switch signal circuit and the ground circuit. With the scan tool, read the park brake switch status. Does the scan tool display SET? | Go to Step 7 | Go to Step 5 |
| 5 | Test for an open or high resistance in the park brake switch signal circuit or ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 10 | Go to Step 6 |
| 6 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 8 |
| 7 | Inspect for poor connections at the harness connector of the park brake switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 9 |
| 8 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 10 | |
| 9 | Replace the park brake switch. Refer to Park Brake Warning Lamp Switch Replacement in Park Brake. Did you complete the replacement? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Daytime Running Lamps (DRL) On with Park Brake Applied
Fog Lamp Indicator Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Fog Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the fog lamp indicator is inoperative. Does the fog lamp indicator operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Do the fog lamps operate normally? | Go to Step 4 | Go to Symptoms - Lighting Systems |
| 4 | Test the fog lamp relay control circuit that provides the ground for the fog lamp indicator for an open or high resistance. Refer to Circuit Testing or Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
| 5 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 6 | |
| 6 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Fog Lamp Indicator Inoperative
Fog Lamps Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Fog Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the front fog lamps are always on. Do the front fog lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Remove the front fog lamp relay. Do the front fog lamps turn OFF? | Go to Step 4 | Go to Step 6 |
| 4 | Ensure that the front fog lamp switch is in the OFF position. Test for a ground signal at the front fog lamp relay control circuit terminal in the underhood fuse block. Refer to Circuit Testing in Wiring Systems. Was a ground signal found? | Go to Step 5 | Go to Step 8 |
| 5 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
| 6 | Repair the short to voltage in the front fog lamp supply voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 9 | |
| 7 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | |
| 8 | Replace the front fog lamp relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the repair? | Go to Step 9 | |
| 9 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Fog Lamps Always On
Fog Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Fog Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the front fog lamps are inoperative. Do the front fog lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Is only one front fog lamp inoperative? | Go to Step 4 | Go to Step 5 |
| 4 | Inspect the inoperative bulb and socket for an open filament or poor terminal contact and replace as necessary. If no problem is found, locate and repair the open or high resistance in the front fog lamp supply voltage circuit or ground circuit to the inoperative lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 16 | |
| 5 | With the engine Off, turn the key to RUN and the headlamp switch to PARK. Do the park lamps illuminate? | Go to Step 6 | Go to Symptoms - Lighting Systems |
| 6 | Inspect the FOG LP fuse. Is the fuse open? | Go to Step 7 | Go to Step 8 |
| 7 | Test for a short to ground in the front fog lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 16 | Go to Step 14 |
| 8 | Place the front fog lamp switch in the ON position. Remove the front fog lamp relay. Test for a ground signal at the front fog lamp relay control circuit terminal in the underhood fuse block. Refer to Circuit Testing in Wiring Systems. Was a ground signal present? | Go to Step 11 | Go to Step 9 |
| 9 | Test the front fog lamp switch signal and ground circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 16 | Go to Step 10 |
| 10 | Remove the fog lamp switch. Place a fused jumper between the fog lamp switch signal and ground connector terminals. Test for a ground signal at the front fog lamp relay control circuit terminal in the underhood fuse block. Refer to Circuit Testing in Wiring Systems. Was a ground signal present? | Go to Step 15 | Go to Step 12 |
| 11 | Test for an open or high resistance in the front fog lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 16 | Go to Step 14 |
| 12 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 16 | Go to Step 13 |
| 13 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 16 | |
| 14 | Replace the front fog lamp relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the repair? | Go to Step 16 | |
| 15 | Replace the front fog lamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 16 | |
| 16 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Fog Lamps Inoperative
Fog Lamps Always On - Rear
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Fog Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the rear fog lamp is always on. Does the rear fog lamp operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Use the scan tool to monitor the rear fog lamp switch input with the switch in the OFF position. Does the scan tool indicate that the switch is ON? | Go to Step 4 | Go to Step 5 |
| 4 | Test for a short to ground in the rear fog lamp switch signal circuit. Did you find and correct the condition? | Go to Step 12 | Go to Step 10 |
| 5 | Remove the rear fog lamp relay. Does the rear fog lamp turn OFF? | Go to Step 6 | Go to Step 8 |
| 6 | Ensure that the rear fog lamp switch is in the OFF position. Test for a ground signal at the rear fog lamp relay control circuit terminal in the body relay block. Refer to Circuit Testing in Wiring Systems. Was a ground signal found? | Go to Step 7 | Go to Step 11 |
| 7 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 12 | Go to Step 9 |
| 8 | Repair the short to voltage in the rear fog lamp supply voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 12 | |
| 9 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 12 | |
| 10 | Replace the rear fog lamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 12 | |
| 11 | Replace the rear fog lamp relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the repair? | Go to Step 12 | |
| 12 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Fog Lamps Always On - Rear
Fog Lamps Inoperative - Rear
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Fog Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the rear fog lamp is inoperative. Does the rear fog lamp operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Test the inoperative bulb or tail lamp printed circuit board for an open or poor terminal contact and replace as necessary. Refer to Circuit Testing in Wiring Systems or Tail Lamp Bulb Replacement or Tail Lamp Circuit Board Replacement . Did you find and correct a condition? | Go to Step 15 | Go to Step 4 |
| 4 | With the engine Off, turn the key to RUN and the headlamp switch to PARK. Do the park lamps illuminate? | Go to Step 5 | Go to Symptoms - Lighting Systems |
| 5 | Inspect the RR FOG fuse. Is the fuse open? | Go to Step 6 | Go to Step 7 |
| 6 | Test for a short to ground in the rear fog lamp supply voltage circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 15 | Go to Step 13 |
| 7 | Place the rear fog lamp switch in the ON position. Remove the rear fog lamp relay. Test for a ground signal at the rear fog lamp relay control circuit terminal in the body relay block. Refer to Circuit Testing in Wiring Systems. Was a ground signal present? | Go to Step 10 | Go to Step 8 |
| 8 | Test the rear fog lamp switch signal and ground circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 15 | Go to Step 9 |
| 9 | Remove the fog lamp switch. Place a fused jumper between the fog lamp switch signal and ground connector terminals. Test for a ground signal at the rear fog lamp relay control circuit terminal in the body relay block. Refer to Circuit Testing in Wiring Systems. Was a ground signal present? | Go to Step 14 | Go to Step 11 |
| 10 | Test for an open or high resistance in the rear fog lamp supply voltage circuit and the ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 15 | Go to Step 13 |
| 11 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 15 | Go to Step 12 |
| 12 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 15 | |
| 13 | Replace the rear fog lamp relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the repair? | Go to Step 15 | |
| 14 | Replace the rear fog lamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 15 | |
| 15 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Fog Lamps Inoperative - Rear
Hazard Lamps Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you review the Exterior Lighting Systems Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Exterior Lighting Systems Description and Operation |
| 2 | Verify that the hazard lamps are always on. Do the hazard lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Disconnect the turn/hazard flasher. Ensure that the hazard lamp switch is in the OFF position. Test for a ground signal at the hazard switch signal circuit input terminal of the hazard/turn flasher connector. Refer to Circuit Testing in Wiring Systems. Is a ground signal present? | Go to Step 4 | Go to Step 5 |
| 4 | Test the multifunction turn signal switch hazard switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 9 | Go to Step 6 |
| 5 | Inspect for poor connections at the harness connector of the hazard/turn flasher. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the multifunction turn signal switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
| 7 | Replace the hazard/turn flasher. Refer to Hazard and Turn Signal Flasher Replacement . Did you complete the repair? | Go to Step 9 | |
| 8 | Replace the multifunction turn signal switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the repair? | Go to Step 9 | |
| 9 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Hazard Lamps Always On
Hazard Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you review the Exterior Lighting Systems Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Exterior Lighting Systems Description and Operation |
| 2 | Verify that the hazard lamps are inoperative. Do the hazard lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Do the turn signal lamps operate normally? | Go to Step 4 | Go to Symptoms - Lighting Systems |
| 4 | Disconnect the turn/hazard flasher. Activate the hazard lamp switch. Test for a ground signal at the hazard switch signal circuit input terminal of the turn/hazard flasher connector. Refer to Circuit Testing in Wiring Systems. Is a ground signal present? | Go to Step 6 | Go to Step 5 |
| 5 | Test the multifunction turn signal switch hazard switch signal circuit and ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 10 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the hazard/turn flasher. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 10 | Go to Step 8 |
| 7 | Inspect for poor connections at the harness connector of the multifunction turn signal switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 9 |
| 8 | Replace the hazard/turn flasher. Refer to Hazard and Turn Signal Flasher Replacement . Did you complete the repair? | Go to Step 10 | |
| 9 | Replace the multifunction turn signal switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the repair? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Hazard Lamps Inoperative
Headlamp Switch On Indicator Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Interior Lights Dimming Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the headlamp switch on indicator is always ON. Does the headlamp switch on indicator operate properly? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Are the headlamps operating properly? | Go to Step 4 | Go to Symptoms - Lighting Systems |
| 4 | Disconnect the headlamp switch. Test for a ground signal at the headlamp on indicator control terminal of the headlamp switch connector. Is a ground signal present? | Go to Step 5 | Go to Step 6 |
| 5 | Test the headlamp on indicator control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 10 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 8 |
| 7 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 9 |
| 8 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 10 | |
| 9 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Headlamp Switch On Indicator Always On
Headlamp Switch On Indicator Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Interior Lights Dimming Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the headlamp switch on indicator is inoperative. Does the headlamp switch on indicator operate properly? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Are the headlamps operating properly? | Go to Step 4 | Go to Symptoms - Lighting Systems |
| 4 | Turn the headlamp switch to the HEAD position. Test for a ground signal at the headlamp on indicator control terminal of the headlamp switch connector. Is a ground signal present? | Go to Step 6 | Go to Step 5 |
| 5 | Test the headlamp on indicator control circuit for an open, high resistance or short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 11 | Go to Step 8 |
| 6 | Test the headlamp indicator LED dimming circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 11 | Go to Step 7 |
| 7 | Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 9 |
| 8 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 10 |
| 9 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 11 | |
| 10 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 11 | |
| 11 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Headlamp Switch On Indicator Inoperative
Headlamps Always On - Low or High Beam (Standard)
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Verify that the high or low beam headlamps are always ON. Do the high and low beam headlamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
| 3 | Are only the high beam headlamps always ON? | Go to Step 4 | Go to Step 8 |
| 4 | Disconnect the headlamp dimmer switch. Do the high beam headlamps remain always ON? | Go to Step 5 | Go to Step 10 |
| 5 | Test the following circuits for a short to ground as applicable. Refer to Circuit Testing and Wiring Repairs . The headlamp dimmer switch signal The headlamp switch flash to pass (FTP) signal Did you find and correct a condition? | Go to Step 18 | Go to Step 6 |
| 6 | Remove the high beam relay. Do the high beam headlamps remain always ON? | Go to Step 12 | Go to Step 7 |
| 7 | Test for a ground signal at the high beam relay control circuit connector terminal. Refer to Circuit Testing . Is a ground control signal present? | Go to Step 11 | Go to Step 15 |
| 8 | Remove the headlamp driver module (HDM). Do the low beam headlamps remain always ON? | Go to Step 13 | Go to Step 9 |
| 9 | Test for a voltage signal at the headlamp low beam relay control circuit connector terminal. Refer to Circuit Testing . Is a voltage control signal present? | Go to Step 11 | Go to Step 16 |
| 10 | Inspect for poor connections at the harness connector of the headlamp dimmer switch. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 18 | Go to Step 17 |
| 11 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 18 | Go to Step 14 |
| 12 | Repair the short to voltage in the right or left high beam headlamp supply voltage circuit. Refer to Wiring Repairs . Did you find and correct a condition? | Go to Step 18 | |
| 13 | Repair the short to voltage in the right or left low beam headlamp supply voltage circuit. Refer to Wiring Repairs . Did you find and correct a condition? | Go to Step 18 | |
| 14 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 18 | |
| 15 | Replace the high beam headlamp relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) . Did you complete the repair? | Go to Step 18 | |
| 16 | Replace the HDM. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) . Did you complete the repair? | Go to Step 18 | |
| 17 | Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal Switch Replacement . Did you complete the repair? | Go to Step 18 | |
| 18 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Headlamps Always On - Low or High Beam (Standard)
Headlamps Inoperative - High Beams
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the high beam headlamps are inoperative. Do the high beam headlamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Is only one high beam headlamp inoperative? | Go to Step 4 | Go to Step 5 |
| 4 | Inspect the inoperative bulb for an open filament and connector for poor terminal contact and replace/repair as necessary. Refer to Headlamp Bulb Replacement (TrailBlazer) or Headlamp Bulb Replacement (Envoy, Envoy XUV, Rainier) or Wiring Repairs in Wiring Systems. If no problem is found, repair the open, high resistance or short to ground in the high beam headlamp supply voltage circuit or ground circuit to the inoperative lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 13 | |
| 5 | Test the headlamp dimmer switch signal and ground circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 13 | Go to Step 6 |
| 6 | Place the headlamp switch in the HEAD position. Connect a fused jumper from ground to the headlamp dimmer switch signal terminal of the headlamp dimmer switch connector. Do the high beam headlamps illuminate? | Go to Step 8 | Go to Step 7 |
| 7 | Connect a fused jumper from ground to the high beam headlamp relay control circuit terminal at the high beam headlamp relay in the underhood fuse block. Do the high beam headlamps illuminate? | Go to Step 9 | Go to Step 11 |
| 8 | Inspect for poor connections at the harness connector of the headlamp dimmer switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
| 9 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 10 |
| 10 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 13 | |
| 11 | Replace the high beam headlamp relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the repair? | Go to Step 13 | |
| 12 | Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the repair? | Go to Step 13 | |
| 13 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Headlamps Inoperative - High Beams
Headlamps Inoperative - Low Beams (Standard)
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 2 | Verify that the low beam headlamps are inoperative. Do the low beam headlamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections | Go to Step 3 |
| 3 | Is only one low beam headlamp inoperative? | Go to Step 4 | Go to Step 5 |
| 4 | Inspect the inoperative bulb for an open filament and connector for poor terminal contact and replace/repair as necessary. Refer to Headlamp Bulb Replacement (TrailBlazer) or Headlamp Bulb Replacement (Envoy, Envoy XUV, Rainier) or Wiring Repairs . If no problem is found, repair the open, high resistance or short to ground in the low beam headlamp supply voltage circuit or ground circuit to the inoperative lamp. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair? | Go to Step 14 | |
| 5 | Test the headlamp switch signal and ground circuits for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct a condition? | Go to Step 14 | Go to Step 6 |
| 6 | Place the headlamp switch in the HEAD position. Connect a fused jumper from ground to the headlamp switch signal terminal of the headlamp switch connector. Do the low beam headlamps illuminate? | Go to Step 9 | Go to Step 7 |
| 7 | Connect a fused jumper from ground to the headlamp driver module control circuit terminal at the headlamp driver module (HDM) in the underhood fuse block. Do the low beam headlamps illuminate? | Go to Step 10 | Go to Step 8 |
| 8 | Test the headlamp driver module ground circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs . Did you find and correct a condition? | Go to Step 14 | Go to Step 12 |
| 9 | Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 14 | Go to Step 13 |
| 10 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 14 | Go to Step 11 |
| 11 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 14 | |
| 12 | Replace the HDM. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) . Did you complete the repair? | Go to Step 14 | |
| 13 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 14 | |
| 14 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Headlamps Inoperative - Low Beams (Standard)
Headlamps Inoperative - Flash to Pass
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Headlights/Daytime Running Lights (DRL) Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the flash to pass (FTP) is inoperative. Does the FTP operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Do the high beam headlamps operate normally? | Go to Symptoms - Lighting Systems | Go to Step 4 |
| 4 | Turn the key to RUN with the engine OFF. Connect a fused jumper from ground to the headlamp switch flash to pass signal terminal of the headlamp dimmer switch connector. Do the high beam headlamps illuminate? | Go to Step 6 | Go to Step 5 |
| 5 | Test the headlamp switch flash to pass signal circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 10 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the headlamp dimmer switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 9 |
| 7 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 8 |
| 8 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 10 | |
| 9 | Replace the headlamp dimmer switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the repair? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Headlamps Inoperative - Flash to Pass
Headlight Leveling Inoperative
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| Schematic Reference: Headlight Leveling Schematics Connector End View Reference: Lighting Systems Connector End Views | ||||
| 1 | Did you review the Exterior Lighting Systems Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Exterior Lighting Systems Description and Operation | |
| 2 | Verify that the headlight leveling is inoperative. Does the headlight leveling operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 | |
| 3 | Inspect the IGN E fuse. Is the fuse good? | Go to Step 4 | Go to Step 10 | |
| 4 | With ignition switch in RUN, test the ignition 1 voltage circuit at the headlamp inoperative leveling actuator connector. Refer to Circuit Testing in Wiring Systems. Is the specified voltage present? | B+ | Go to Step 5 | Go to Step 11 |
| 5 | Test the ground circuit at the inoperative headlamp actuator connector for continuity to ground. Refer to Circuit Testing in Wiring Systems. Is continuity present? | Go to Step 6 | Go to Step 12 | |
| 6 | Connect a digital multimeter (DMM) from ground to the headlamp leveling motor supply voltage circuit at the inoperative headlamp leveling actuator connector and adjust the headlamp leveling switch from the highest to lowest setting. Refer to Circuit Testing in Wiring Systems. Does the DMM display within the specified range? | 2.0 V-8.0 V | Go to Step 16 | Go to Step 7 |
| 7 | Test the ground circuit of the headlamp leveling switch for continuity to ground. Refer to Circuit Testing in Wiring Systems. Is there continuity? | Go to Step 8 | Go to Step 13 | |
| 8 | Test the ignition 1 voltage circuit at the headlamp leveling switch connector. Refer to Circuit Testing in Wiring Systems. Is the specified voltage present? | B+ | Go to Step 9 | Go to Step 15 |
| 9 | With the ignition switch in the OFF position, test for an open, high resistance, short to ground, or short to voltage in the headlamp leveling motor supply voltage circuit. Refer to Circuit Testing in Wiring Systems. Did you find a condition? | Go to Step 14 | Go to Step 17 | |
| 10 | Repair the short to ground in the ignition 1 voltage circuit. Refer to Wiring Repairs and Power Distribution Schematics in Wiring Systems. Did you complete the repair? | Go to Step 18 | ||
| 11 | Repair the open or high resistance in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Is repair complete? | Go to Step 18 | ||
| 12 | Repair the open or high resistance in the ground circuit. Refer to Wiring Repairs in Wiring Systems. Is repair complete? | Go to Step 18 | ||
| 13 | Repair the open or high resistance in the ground circuit. Refer to Wiring Repairs in Wiring Systems. Is repair complete? | Go to Step 18 | ||
| 14 | Repair open, high resistance, short to ground, or short to voltage in the headlamp leveling motor supply voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 18 | ||
| 15 | Repair the open or high resistance in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 18 | ||
| 16 | Replace the inoperative headlamp leveling actuator. Refer to Headlamp Replacement (TrailBlazer) or Headlamp Replacement (Envoy, Envoy XUV) or Headlamp Replacement (Rainier) . Is repair complete? | Go to Step 18 | ||
| 17 | Replace headlamp leveling switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 18 | ||
| 18 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 | |
Headlight Leveling Inoperative
High Beam Indicator Always On
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the high beam indicator is always on. Does the high beam indicator operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Turn the ignition switch to the RUN position. Turn the headlamp switch to the HEAD position. Place the multifunction headlamp dimmer switch to the high beams position. Do the high beam headlamps function properly? | Go to Step 4 | Go to Symptoms - Lighting Systems |
| 4 | Using a scan tool, select IPC, Special Functions, and command the Lamp Test ON, then OFF. Does the high beam indicator lamp turn ON and OFF when commanded? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 5 |
| 5 | Inspect for poor connections at the harness connector of the instrument panel cluster (IPC). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 6 |
| 6 | Replace the IPC. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 7 | |
| 7 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
High Beam Indicator Always On
High Beam Indicator Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the high beam indicator is inoperative. Does the high beam indicator operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Turn the ignition switch to the RUN position. Turn the headlamp switch to the HEAD position. Place the multifunction headlamp dimmer switch to the high beams position. Do the high beam headlamps function properly? | Go to Step 4 | Go to Symptoms - Lighting Systems |
| 4 | Using a scan tool, select IPC, Special Functions, and command the Lamp Test ON, then OFF. Does the high beam indicator lamp turn ON and OFF when commanded? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 5 |
| 5 | Inspect for poor connections at the harness connector of the instrument panel cluster (IPC). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 6 |
| 6 | Replace the IPC. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 7 | |
| 7 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
High Beam Indicator Inoperative
Interior Backlighting Does Not Dim
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Interior Lights Dimming Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the interior backlighting does not dim. Does the interior backlighting operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Use the scan tool output controls to operate the interior backlighting. Can you control the dimming level of an activated control switch indicator with the scan tool? | Go to Step 4 | Go to Step 5 |
| 4 | Test for an open, high resistance or short to ground in the following circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. The 5-volt reference The dimming input The dimming return Did you find and correct a condition? | Go to Step 10 | Go to Step 6 |
| 5 | Test for a short to voltage in the LED dimming circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 10 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 8 |
| 7 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 9 |
| 8 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the replacement? | Go to Step 10 | |
| 9 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Interior Backlighting Does Not Dim
Interior Backlighting Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Interior Lights Dimming Schematics Connector End View Reference: Master Electrical Component List in Wiring Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the interior backlighting is inoperative. Does the interior backlighting operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Are all of the interior backlighting lamps inoperative? | Go to Step 5 | Go to Step 4 |
| 4 | Test for an open or high resistance in the following circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. The instrument panel lamps dimming control The ground Did you find and correct a condition? | Go to Step 10 | Go to Step 6 |
| 5 | Test for the following conditions. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Short to ground in the instrument panel lamps dimming control circuit Short to voltage in the dimming input circuit Open or high resistance in the dimming return circuit Did you find and correct a condition? | Go to Step 10 | Go to Step 7 |
| 6 | Inspect for poor connections at the harness connector of the affected lamp. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 8 |
| 7 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 9 |
| 8 | Replace the affected lamp or internal lamp component. Did you complete the replacement? | Go to Step 10 | |
| 9 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Interior Backlighting Inoperative
License Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the license lamps are inoperative. Do the license lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Is the left tail lamp inoperative also? | Go to Step 5 | Go to Step 4 |
| 4 | Inspect the inoperative bulbs/sockets for open filaments or poor terminal contact. Does any lamp have an open filament or poor terminal contact? | Go to Step 7 | Go to Step 6 |
| 5 | Repair the short to ground in the license lamp supply voltage circuit or left tail lamp tail supply voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | |
| 6 | Repair the open or high resistance in the license lamps supply voltage circuit or ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | |
| 7 | Replace the inoperative bulb or repair/replace the socket. Refer to Wiring Repairs in Wiring Systems or License Lamp Replacement . Did you complete the repair? | Go to Step 8 | |
| 8 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
License Lamps Inoperative
Marker Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the marker lamps are inoperative. Do the marker lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Place the headlamp switch in the PARK position. Do the park lamps operate normally? | Go to Step 4 | Go to Symptoms - Lighting Systems |
| 4 | Inspect the inoperative bulb and socket for an open filament or poor terminal connections. Does any lamp have an open filament or poor terminal connections? | Go to Step 6 | Go to Step 5 |
| 5 | Repair the open or high resistance in one of the following circuits. Refer to Wiring Repairs in Wiring Systems: Marker lamp supply voltage Front turn signal lamp supply voltage-Domestic vehicle only Ground-Export vehicle only Did you complete the repair? | Go to Step 7 | |
| 6 | Replace the defective bulb or repair/replace the socket. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 7 | |
| 7 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Marker Lamps Inoperative
Memory/Heated Seat Switch Backlighting Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Interior Lights Dimming Schematics Connector End View Reference: Lighting Systems Connector End Views , Computer/Integrating Systems Connector End Views in Computer/Integrating Systems, or Power Door Systems Connector End Views in Doors | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the memory/heated switch backlighting is inoperative. Does the memory/heated switch backlighting operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Are any other dimmable interior backlighting lamps inoperative? | Go to Interior Backlighting Inoperative | Go to Step 4 |
| 4 | Place the headlamp switch in the PARK position. Adjust the instrument panel (I/P) dimmer switch to the full intensity position. Test for an open, high resistance, or short to voltage in the memory/heated seat switch illumination control circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition? | Go to Step 10 | Go to Step 5 |
| 5 | Use a test lamp connected to B+ to backprobe the memory/heated seat switch illumination control circuit terminal at the driver door module (DDM) connector. Does the test lamp illuminate? | Go to Step 7 | Go to Step 6 |
| 6 | Inspect for poor connections at the harness connector of the DDM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 8 |
| 7 | Inspect for poor connections at the harness connector of the memory/heated seat switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 10 | Go to Step 9 |
| 8 | Replace the DDM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 10 | |
| 9 | Replace the memory/heated seat switch. Refer to Memory Seat Switch Replacement in Seats. Did you complete the replacement? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Memory/Heated Seat Switch Backlighting Inoperative
Park Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Computer/Integrating Systems Connector End Views in Vehicle DTC Information |
| 2 | Verify that the front park lamps are inoperative. Do the park lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Inspect the F PARK fuse in the body relay block. Is the fuse open? | Go to Step 5 | Go to Step 4 |
| 4 | Inspect the inoperative bulbs/sockets for open or shorted filaments/terminals. Does any lamp have an open or shorted filament/terminals? | Go to Step 7 | Go to Step 6 |
| 5 | Repair the short to ground in the front park lamps supply voltage circuit or cornering lamps supply voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | |
| 6 | Repair the open or high resistance in the front park lamps supply voltage circuit or ground circuit to the inoperative lamp. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | |
| 7 | Replace the defective bulb/socket. Refer to Park/Turn Signal/Side Marker Lamp Bulb Replacement (Envoy) or Park/Turn Signal/Side Marker Lamp Bulb Replacement (TrailBlazer) or Park/Turn Signal/Side Marker Lamp Bulb Replacement (Rainier) . Did you complete the repair? | Go to Step 8 | |
| 8 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Park Lamps Inoperative
Stop Lamps Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you review the Exterior Lighting Systems Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Exterior Lighting Systems Description and Operation |
| 2 | Verify that the stop lamps are always on. Do the stop lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Disconnect the stop lamp switch. Do the stop lamps remain illuminated? | Go to Step 4 | Go to Step 6 |
| 4 | Disconnect the turn/hazard flasher. Do the stop lamps remain illuminated? | Go to Step 5 | Go to Step 7 |
| 5 | Repair the short to voltage in one of the following circuits. Refer to Wiring Repairs in Wiring Systems. Stop lamp switch signal CHMSL supply voltage Stop lamp supply voltage Did you complete the repair? | Go to Step 8 | |
| 6 | Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement . Did you complete the repair? | Go to Step 8 | |
| 7 | Replace the hazard/turn flasher. Refer to Hazard and Turn Signal Flasher Replacement . Did you complete the repair? | Go to Step 8 | |
| 8 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Stop Lamps Always On
Stop Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you review the Exterior Lighting Systems Description and Operation and perform the necessary inspections? | Go to Step 2 | Go to Exterior Lighting Systems Description and Operation |
| 2 | Verify that the stop lamps are inoperative. Do the stop lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Is only one lamp inoperative? | Go to Step 4 | Go to Step 5 |
| 4 | Test the inoperative bulb, LED, or tail lamp printed circuit board for an open or poor terminal contact. Refer to Circuit Testing in Wiring Systems. Did you find a condition? | Go to Step 10 | Go to Step 9 |
| 5 | Connect a test lamp from ground to the supply voltage circuit terminal of the inoperative lamp socket or connector and apply the service brake. Refer to Circuit Testing in Wiring Systems. Does the test lamp illuminate? | Go to Step 7 | Go to Step 6 |
| 6 | Remove the stop lamp switch and install a fused jumper between the stop lamp switch battery positive voltage circuit terminal and the stop lamp switch signal circuit terminal of the stop lamp switch connector. Do the stop lamps illuminate? | Go to Step 11 | Go to Step 8 |
| 7 | Repair the open or high resistance in the ground circuit of the inoperative lamp. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 12 | |
| 8 | Repair the open, high resistance or short to ground in one of the following circuits. Refer to Wiring Repairs in Wiring Systems. Battery positive voltage Stop lamp switch signal Lamp supply voltage Is the repair complete? | Go to Step 12 | |
| 9 | Repair one of the following conditions. Refer to Wiring Repairs in Wiring Systems. An open, high resistance or short to ground in the lamp supply voltage circuit. An open or high resistance in the ground circuit. Is the repair complete? | Go to Step 12 | |
| 10 | Replace the inoperative bulb, high mounted stop lamp assembly, or tail lamp printed circuit. Refer to Tail Lamp Bulb Replacement , High Mounted Stop Lamp Replacement (Envoy XUV) or High Mounted Stop Lamp Replacement (Envoy, TrailBlazer, Rainier) , or Tail Lamp Circuit Board Replacement . Is the repair complete? | Go to Step 12 | |
| 11 | Replace the stop lamp switch. Refer to Stop Lamp Switch Replacement . Did you complete the repair? | Go to Step 12 | |
| 12 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Stop Lamps Inoperative
Tail Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the tail lamps are inoperative. Do the tail lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Inspect the appropriate fuse for the inoperative lamps in the body relay block. Is the fuse open? | Go to Step 5 | Go to Step 4 |
| 4 | Test the inoperative bulb or tail lamp printed circuit board for an open or poor terminal contact. Refer to Circuit Testing in Wiring Systems. Did you find a condition? | Go to Step 7 | Go to Step 6 |
| 5 | Repair the short to ground in the inoperative tail lamps supply voltage circuit or license lamp supply voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | |
| 6 | Repair the open or high resistance in the inoperative tail lamps supply voltage circuit or ground circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 8 | |
| 7 | Replace the defective bulb or tail lamp printed circuit board. Refer to Tail Lamp Bulb Replacement or Tail Lamp Circuit Board Replacement . Did you complete the repair? | Go to Step 8 | |
| 8 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Tail Lamps Inoperative
Tail, Marker, and License Lamps Always On
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the tail, marker and license lamps are always on. Do the tail, marker and license lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Remove the park lamp relay. Do the park lamps turn OFF? | Go to Step 4 | Go to Step 9 |
| 4 | Ensure that the headlamp switch is in the OFF position and there is sufficient light to the ambient light sensor. Test for a ground signal at the park lamp relay control circuit terminal in the body relay block. Refer to Circuit Testing in Wiring Systems. Was a ground signal present? | Go to Step 5 | Go to Step 10 |
| 5 | Use the scan tool to check the body control module (BCM) park lamp switch input data. Does the scan tool indicate a park lamps OFF request signal? | Go to Step 8 | Go to Step 6 |
| 6 | Test for a short to ground in the park lamp switch signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 7 |
| 7 | Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 11 |
| 8 | Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
| 9 | Repair the short to voltage in one of the following circuits. Refer to Wiring Repairs in Wiring Systems: The park lamp supply voltage The tail lamp supply voltage The license lamp supply voltage The marker lamp supply voltage Did you complete the repair? | Go to Step 13 | |
| 10 | Replace the park lamp relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the repair? | Go to Step 13 | |
| 11 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 13 | |
| 12 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 13 | |
| 13 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Tail, Marker, and License Lamps Always On
Tail, Marker, and License Lamps Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Computer/Integrating Systems Connector End Views in Computer/Integrating Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Computer/Integrating Systems Connector End Views in Vehicle DTC Information |
| 2 | Verify that the tail, marker and license lamps are inoperative. Do the tail, marker and license lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Remove the park lamp relay. Ensure that the headlamp switch is in the HEAD position. Test for a ground signal at the park lamp relay control circuit terminal in the body relay block. Refer to Circuit Testing in Wiring Systems. Was a ground signal present? | Go to Step 8 | Go to Step 4 |
| 4 | Use the scan tool to check the body control module (BCM) park lamp switch input data. Does the scan tool indicate a park lamps ON request signal? | Go to Step 7 | Go to Step 5 |
| 5 | Test for an open or high resistance in the park lamp switch signal circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 6 |
| 6 | Inspect for poor connections at the harness connector of the headlamp switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 9 |
| 7 | Inspect for poor connections at the harness connector of the BCM. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 10 |
| 8 | Replace the park lamp relay. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Did you complete the repair? | Go to Step 11 | |
| 9 | Replace the headlamp switch. Refer to Headlamp Switch Replacement . Did you complete the repair? | Go to Step 11 | |
| 10 | Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 11 | |
| 11 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Tail, Marker, and License Lamps Inoperative
Turn Signal Lamps and/or Indicators Always On or Flashing
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Instrument Panel, Gages, and Console Connector End Views in Instrument Panel, Gages, and Console or Power Door Systems Connector End Views in Doors | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the turn signal lamps and/or indicators are always on or flashing. Do the turn signal lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Are only the turn signal indicators in the instrument panel cluster (IPC) always on or flashing? | Go to Step 9 | Go to Step 4 |
| 4 | Are only the turn signal lamps on one side of the vehicle always on or flashing? | Go to Step 5 | Go to Step 7 |
| 5 | Inspect the affected bulb/socket for an internal short, poor terminal contact, or a shorted filament. Was a problem found? | Go to Step 14 | Go to Step 6 |
| 6 | Test the following circuits of the affected lamps for a short to voltage. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. The left or right turn signal lamp supply voltage The left or right turn flasher signal The left or right turn signal switch signal The left or right trailer stop/turn lamp supply voltage Did you find and correct the condition? | Go to Step 18 | Go to Step 7 |
| 7 | Disconnect the multifunction turn signal switch. Do the affected turn signals and indicators still illuminate? | Go to Step 8 | Go to Step 10 |
| 8 | Disconnect the front door module on the same side as the affected lamps. Do some of the affected turn signal lamps and indicators still illuminate? | Go to Step 11 | Go to Step 12 |
| 9 | Inspect for poor connections at the IPC. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 18 | Go to Step 13 |
| 10 | Inspect for poor connections at the multifunction turn signal switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 18 | Go to Step 15 |
| 11 | Inspect for poor connections at the turn/hazard flasher. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 18 | Go to Step 16 |
| 12 | Inspect for poor connections at the front door module on the same side as the affected lamps. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 18 | Go to Step 17 |
| 13 | Replace the IPC. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the repair? | Go to Step 18 | |
| 14 | Replace or repair the affected bulb/socket. Did you complete the repair? | Go to Step 18 | |
| 15 | Replace the multifunction turn signal switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the repair? | Go to Step 18 | |
| 16 | Replace the hazard/turn flasher. Refer Hazard and Turn Signal Flasher Replacement . Did you complete the repair? | Go to Step 18 | |
| 17 | IMPORTANT: Perform the set up procedure for the door module. Replace the door module for the inoperative outside rear view mirror turn indicator. Refer to Switch Replacement - Door Lock and Side Window - Driver or Switch Replacement - Door Lock and Side Window - Passenger in Doors.Did you complete the repair? | Go to Step 18 | |
| 18 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
| IMPORTANT |
|---|
| Perform the set up procedure for the door module. |
Turn Signal Lamps and/or Indicators Always On or Flashing
Turn Signal Lamps and/or Indicators Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views or Instrument Panel, Gages, and Console Connector End Views in Instrument Panel, Gages, and Console or Power Door Systems Connector End Views in Doors | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the turn signal lamps and/or indicators are inoperative. Do the turn signal lamps and/or indicators operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Are only the turn signal indicators in the instrument panel cluster (IPC) inoperative? | Go to Step 4 | Go to Step 5 |
| 4 | Test the inoperative turn signal supply voltage circuit to the IPC for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 21 | Go to Step 12 |
| 5 | Is only one turn signal lamp inoperative? | Go to Step 6 | Go to Step 8 |
| 6 | Test the inoperative bulb or tail lamp printed circuit board for an open or poor terminal contact. Refer to Circuit Testing in Wiring Systems. Did you find a condition? | Go to Step 18 | Go to Step 7 |
| 7 | Test for an open, high resistance, or short to ground in the turn signal lamp supply voltage circuit or an open or high resistance in the turn signal lamp ground circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 21 | Go to Step 15 |
| 8 | Inspect the IGN E fuse and the FLASHER fuse. Is either fuse open? | Go to Step 11 | Go to Step 9 |
| 9 | Test for an open or high resistance in the following circuits. Refer to Circuit Testing and Wiring Repairs in Wiring Systems: The turn/hazard flasher battery positive supply voltage The turn/hazard flasher ground The turn signal switch ignition 1 supply voltage Did you find and correct the condition? | Go to Step 21 | Go to Step 10 |
| 10 | Disconnect the multi-function switch turn signal switch. Test the multifunction turn signal switch for continuity between the multifunction turn signal switch ignition 1 voltage input terminal and the turn signal flasher signal output terminal in each respective position. Refer to Circuit Testing in Wiring Systems. Is continuity present? | Go to Step 11 | Go to Step 13 |
| 11 | Test the following circuits for an open, high resistance or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems: The multifunction turn signal switch ignition 1 voltage The turn/hazard flasher supply voltage The left turn flasher signal The right turn flasher signal The left turn lamp supply voltage The right turn lamp supply voltage The left trailer stop/turn lamp supply voltage The right trailer stop/turn lamp supply voltage Did you find and correct the condition? | Go to Step 21 | Go to Step 14 |
| 12 | Inspect for poor connections at the IPC. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 21 | Go to Step 17 |
| 13 | Inspect for poor connections at the multifunction turn signal switch. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 21 | Go to Step 19 |
| 14 | Inspect for poor connections at the turn/hazard flasher. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 21 | Go to Step 20 |
| 15 | Inspect for poor connections at the door module for the inoperative outside rear view mirror turn indicator. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 21 | Go to Step 16 |
| 16 | IMPORTANT: Perform the set up procedure for the door module. Replace the door module for the inoperative outside rear view mirror turn indicator. Refer to Switch Replacement - Door Lock and Side Window - Driver or Switch Replacement - Door Lock and Side Window - Passenger in Doors.Did you complete the repair? | Go to Step 21 | |
| 17 | Replace the IPC. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the repair? | Go to Step 21 | |
| 18 | Replace the inoperative bulb or tail lamp printed circuit board. Refer to Tail Lamp Bulb Replacement or Tail Lamp Circuit Board Replacement . Did you complete the repair? | Go to Step 21 | |
| 19 | Replace the multifunction turn signal switch. Refer to Multifunction, Turn Signal Switch Replacement in Steering Wheel and Column. Did you complete the repair? | Go to Step 21 | |
| 20 | Replace the hazard/turn flasher. Refer to Hazard and Turn Signal Flasher Replacement . Did you complete the repair? | Go to Step 21 | |
| 21 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
| IMPORTANT |
|---|
| Perform the set up procedure for the door module. |
Turn Signal Lamps and/or Indicators Inoperative
Vanity Mirror Lamp(s) Inoperative
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Interior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Verify that the visor vanity mirror lamps are inoperative. Do the visor vanity mirror lamps operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Connect a test lamp from the inadvertent power courtesy lamps supply voltage circuit above the headliner at the inoperative visor vanity mirror connector to ground. Refer to Circuit Testing in Wiring Systems. Does the test lamp illuminate? | Go to Step 4 | Go to Step 5 |
| 4 | Connect a test lamp between the inadvertent power courtesy lamps supply voltage circuit and the ground circuit at the inoperative visor vanity mirror lamp connector. Refer to Circuit Testing in Wiring Systems. Does the test lamp illuminate? | Go to Step 7 | Go to Step 6 |
| 5 | Repair the open, high resistance or short to ground in the inadvertent power courtesy lamps supply voltage circuit. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 8 | |
| 6 | Repair the open or high resistance in the ground circuit. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | Go to Step 8 | |
| 7 | Inspect the inoperative visor mirror bulb for an open filament and replace as necessary. Refer to Vanity Mirror Lamp Bulb Replacement . If the bulb is good, replace the sunshade. Refer to Sunshade Replacement in Interior Trim. Is the repair complete? | Go to Step 8 | |
| 8 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
Vanity Mirror Lamp(s) Inoperative
Screen Method for Headlamp Aiming
The screen method requires an area set up specifically for headlamp aiming.
Scheme 41
The area should consist of a level surface large enough to allow for a vehicle and an additional 7.62 m (25 ft) as measured from the face of the headlamps to the aiming screen.
Scheme 42
The screen should be a wall or other flat surface at least 1.52 m (5 ft) high by 3.66 m (12 ft) wide with a matte white surface well shaded from extraneous light, and 90 degrees to the floor. The screen should be provided with a permanent vertical reference line 0.61 m (2 ft) from the left edge of the screen, 2 laterally adjustable vertical tapes, and one vertically adjustable horizontal tape.
After the aiming screen has been set up and located, paint or tape a reference line on the floor 15.24 m (50 ft) from the vertical reference line on the screen. This line should be perpendicular to the aiming screen and a mark placed at 7.62 m (25 ft) from the screen.
Headlamp Aiming Procedure
- Align the left tires of the vehicle with the reference line extending from the screen with the headlamps aligned with the reference line.
- Remove any snow, ice or mud from the vehicle.
- The vehicle must be fully assembled and all other work stopped while the headlamp aiming is being done.
- The vehicle must contain one person or approximately 160 lb (73 kg).
- Tires should be properly inflated.
- Rock the vehicle to stabilize the suspension.
- Measure from the floor to the reference mark on the headlamp lens (2). The graphic shows a GMC headlamp. Chevrolet and Oldsmobile are similar.
- At the screen, measure from the floor and place the horizontal tape at the above measured distance.
- Turn the low beam headlamps ON.
- The graphic shows the vertical (1) adjustment, no horizontal adjustments are required. The graphic shows a GMC headlamp. Chevrolet and Oldsmobile are similar. Adjust the headlamps to the specifications required by state and local authorities.
- The beam pattern must be positioned as shown in the graphic.
- Adjust one headlamp at a time while blocking the light from the other. The cover must be away from the headlamp. The following list refers to the callouts in the graphic: The low beam centerline reference mark (4). Distance from ground to the low beam bulb centerline reference mark (1). The ground line (2). Horizontal edge of the low beam headlamp pattern (3). The edge of the headlamp pattern (3), must be 5 cm (2 in) below the reference mark (4), with the vehicle 7.62 m (25 ft) away.
Fog Lamp Aiming Procedure
Proper road illumination and safety require the fog lamps to be aimed. The front fog lamp aim should be checked when a new front fog lamp assembly is installed, or if any service repairs have been performed to the vehicle which disturb the front fog lamp mounting or the vehicle ride height.
There are no horizontal adjustments for aiming the front fog lamp assemblies on this vehicle.
Scheme 43
The front foglamps can be adjusted by turning the adjustment screw (1) located below the backside of the lamp, next to the electrical connector.
Use the following guidelines in order to adjust the aim
- Turn the TORX® adjustment screw clockwise in order to raise the aim.
- Turn the TORX® adjustment screw counter-clockwise in order to lower the aim.
- To ensure accurate vertical front fog lamp aiming, first perform the following steps to prepare the vehicle. Make sure that all the components are in place on the vehicle, the tires are properly inflated, and there is not any mud or snow clinging to the vehicle. Stop all other operations of work on the vehicle. Make sure the fuel level is 1/2 full or more. Jounce the vehicle to settle the suspension. Place the vehicle on a level surface 7.6 m (25 ft) from the target screen. Measure the distance from the floor to the center of the fog lamp (5). Using this measurement, mark the horizontal centerline of the fog lamp (1) on the target screen directly in front of the vehicle. Start the vehicle in order to level the suspension.
- Turn the front fog lamps ON.
- Access the fog lamp vertical adjuster.
- Adjust the fog lamp up or down until the top edge of the high intensity zone on the screen is 102 mm (4 in) below (2) the horizontal centerline (1).
- Turn OFF the front fog lamps.
Exterior Lamps
The exterior lighting system consist of the following lamps
- The Headlamps
- The Daytime Running Lamps (DRL)
- The Clearance Lamps (Y92 roof rack only)
- The Cornering Lamps
- The Front Fog Lamps
- The Rear Fog Lamps (Export)
- The Park, Tail and Marker Lamps
- The Turn Signal Lamps
- The Stop Lamps
- The Backup Lamps
Headlamps
The headlamp driver module (HDM) is an electronic module that provides electrical power to the vehicle low beam headlamps. The HDM is controlled by a pulse width modulated (PWM) ground signal from the body control module (BCM). The BCM determines the desired lamp intensity using the ambient light sensor, multifunction switch and the park brake switch as inputs. In general, the HDM will operate in 1 of 3 modes
- Reduced Intensity Mode: This mode is used by features that do not require or allow maximum low beam headlamp intensity such as daytime running lights (DRL) (nominal: 85% duty cycle).
- Full Intensity Mode: This mode is used by features that require full low beam headlamp intensity such as low beam headlamp operation in manual or auto modes (nominal: 100% duty cycle).
- Off Mode: This is the default mode of the system that will occur when none of the features described above are active. The BCM will deactivate its PWM output (0% duty cycle) during this mode.
The normal battery voltage input to the HDM must be between 6 and 16 volts DC to operate. Any deviation to these values could cause improper operation.
Major components of this system are the BCM, HDM, ambient light sensor, multifunction switch, park brake switch and low beam headlamps.
The headlamps may be turned on in 2 different ways. First, when the driver places the headlamp switch in the HEADLAMP position, normal operation occurs. Second, with the headlamp switch is placed in the AUTO position, automatic lamp control (ALC) occurs. During ALC control, the headlamps will be in daytime running lamp (DRL) operation in daylight conditions, or low beam operation in low light conditions.
The HDM and high beam relay receive battery positive voltage directly from the battery. The BCM supplies a 100% duty cycle PWM ground signal to the HDM for automatic headlight control and normal headlight operation. The BCM also supplies ground to the high beam relay coil for high beam headlight operation. When the driver places the headlamp switch in the HEADLAMP position and the dimmer switch is in the low beam position, the HDM switches to full output sending current flow through the left and right low beam headlamp fuses to both low beam headlamps. The dimmer switch sends a ground signal to the BCM in the high beam position and a momentary ground signal in the flash-to-Pass (FTP) position from G102 to deactivate the low beam headlights and activate the high beam headlights. With the headlights in the low beam position, the high beams may be momentarily turned on or flashed by activating the FTP portion of the switch.
The instrument panel cluster (IPC) illuminates the high beam indicator when the body control module (BCM) detects that the high beams are requested. The IPC receives a class 2 message from the BCM requesting illumination.
The Headlamps On at Exit and Perimeter Lighting modes can be adjusted using the steering wheel controls to select the desired function as displayed in the driver information center. The Headlamps On at Exit selection will allow the driver to customize the period of time that the headlamps remain illuminated upon exiting the vehicle. This period can be adjusted from 0 seconds to 180 seconds. The Perimeter Lighting feature allows the driver to select if they desire the headlamps and backup lamps to illuminate when the door UNLOCK button on the key fob is activated. This feature can be turned ON or OFF by using the driver information center steering wheel control buttons.
Daytime Running Lamps (DRL)
The ambient light sensor is a light sensitive transistor that varies its voltage signal to the body control module (BCM) in response to changes to the outside (ambient) light level. When the BCM receives this signal it will either turn on the daytime running lamps (DRL) through the HDM using the reduced output or the headlamps at full intensity for auto headlamp operation. Any function or condition that turns on the headlights will cancel the daytime running lamps operation. The daytime running lamps (DRL) are the low beam headlights at a reduced intensity. With the headlight switch in the OFF position, the headlights will either be turned ON or OFF, after an approximate 8 second delay depending on whether daylight or low light conditions are sensed. When the BCM signals the HDM for DRL operation in daylight conditions, the HDM illuminates the low beam headlights at a reduced intensity. The DRL will operate when the ignition switch is in the RUN position, the gear selector is not in the PARK position and the parking brake is released. When these conditions have been met and the ambient light sensor indicates daytime conditions, the DRL will illuminate.
On vehicles equipped with the 4-position headlamp switch, DRL and headlamp operation can be temporarily disabled by momentarily placing the headlamp switch in the DRL defeat position. This will signal the BCM to disable the headlamps until the headlamp switch is momentarily placed in the DRL defeat position again or until the next ignition key cycle.
DRL operation in Manual Transmission equipped vehicles will occur when the ignition switch is in the RUN position, and the parking brake is released.
Headlamp Leveling (Export)
The IGN E fuse in the I/P fuse block supplies battery positive voltage to the headlamp leveling switch. When the driver places the headlamp leveling switch in any position, a signal is sent to the headlamp leveling actuators to adjust the headlight aiming to the desired position. The underhood fuse block supplies battery positive voltage and G107 and G103 supplies ground to the headlamp leveling actuators.
Fog Lamps
With both the ignition switch in the RUN position and the park lamps or low beam head lamps on, the fog lights will illuminate when the driver presses the fog lamp switch. The FOG LAMP fuse in the engine wiring harness junction block supplies battery positive voltage to the fog lamp relay. With the headlamp switch in either the park or headlamp position and the fog lamp switch is pressed, the body control module (BCM) will energize the fog lamp relay control circuit. The current flow is from the fog lamp relay to both front fog lamps and to ground G107 and G103. The state of the fog lamps either ON or OFF will remain the same until the fog lamp switch is pressed again, or the ignition switch is cycled OFF and ON. Fog lamp operation will be cancelled whenever the park lamps are turned OFF or the high beam headlights have been selected.
The rear fog lamp (Export) is located in the left tail lamp assembly. The rear fog lamp has a dedicated relay and both the relay control and current flow operate the same as the front fog lamps. The RR FOG fuse supplies voltage to the lamp and G 401 supplies ground.
Park, Tail, Marker, License, and Clearance Lamps
The park, tail, marker, license, and clearance (Y92 only) lamps are turned on when the headlamp switch is placed in the PARK or ON position or anytime the headlights are requested. The I/P BATT fuse in the engine wiring harness junction block supplies battery positive voltage to both the park lamp relay switch contacts and the park lamp coil circuit. The body control module (BCM) provides a ground or control circuit to the park lamp relay coil circuit. When the park lamps are turned on, the BCM energizes the park lamp relay. Current flow is from the park lamp relay to the individual park lamp circuit fuses and to their respective park, tail, marker, and license lamps. The front park and marker lamps are grounded at G107 and G103. The tail lamps are grounded at G401 and G402. The license lamps are grounded at G401. When equipped with the Y92 roof rack option, the clearance lamps are grounded at G302. If the driver places the headlight switch in the ON position after the ignition switch has been turned OFF, the park, tail, marker, license, and clearance lamps will remain on until turned off or the battery runs dead.
The T PARK fuse in the rear fuse-relay block supplies battery positive voltage to a separate park lamp circuit connected to the trailer wiring harness.
Turn Signal Lamps
The smart flasher (GMSF) is an automotive flasher designed to accept turn, hazard, and brake inputs. The GMSF will provide corresponding outputs to the exterior lamps and instrument panel turn signal indicator lamps. This lighting system has dedicated lamps for the turn/hazard functions and dedicated lamps for the brake function. The system incorporates the use of flash rates for diagnostics. The flash rate is a calculation of the number of flashes that occur within a 60 second period. This system uses a percentage of on-time to off-time called duty cycle. For the bulb outage condition, the indicator of the vehicle side on which the outage occurs shall assume bulb outage flash rate mode. The opposite side indicator will assume the normal flash rate mode for an input from the non bulb outage side of the vehicle. Hazard warning lamp outage will maintain a normal flash rate as long as 2 or more exterior signaling lamps are functional. During all modes of operation, the IPC will receive the same flash rates and duty cycles that the exterior lamps receive. The IPC will then control the indicators in the cluster. The vehicle operator will be provided with an audible and visual indication of the flasher operation. Below is a table with flash rates and duty cycles
| Operating Condition | Flash Rate | Duty Cycle |
|---|---|---|
| Normal | 75 to 105 flashes per minute | 45% to 55% |
| Turn Signal Lamp Outage | 2 or 3 times faster than normal flash rate | 35% to 55% |
Exterior Lighting Systems Description and Operation
The IGN E fuse in the engine wiring harness junction block supplies Ignition positive voltage to the turn signal switch assembly. With the ignition switch in the RUN or START position, ignition positive voltage is connected through the turn signal and hazard switch assembly to the GMSF which is powered by the FLASHER fuse also in the engine wiring harness junction block and is grounded at G201. When the turn signal switch is placed in either the left or right position, the circuit is complete from the GMSF to the turn signal lamps and to ground. The GMSF then sends an on-off voltage signal to either the left or right turn signals and their instrument panel cluster (IPC) indicator. When the hazard switch is pressed, all turn signal lamps will flash including both IPC turn indicators. The front turn signals are grounded at G103 and G107. The rear turn signals are grounded at G401 and G402.
The IPC illuminates the TURN SIGNAL ON indicator in the driver information center when the IPC determines that the turn signal is active for more than 1.2 km (0.75 mile). The IPC also sends a class 2 message to the radio in order to activate the audible warning.
On vehicles equipped with the outside rear view mirror turn signal lamps, the turn signal voltage is also sent to the respective front door module. The door modules then distribute power and ground to the activated lamp.
For trailer wiring, separate turn signal circuits are connected through the GMSF to the trailer wiring harness.
Cornering Lamps
The turn signal switch sends battery positive voltage to the cornering lamps which will constantly remain illuminated until turn signal operation is cancelled. The cornering lamps are grounded at G103 and G107.
Stop Lamps
The STOP fuse in the engine wiring harness junction block supplies battery positive voltage to the normally open stop lamp switch. When the driver presses the brake pedal, the switch contacts close and battery positive voltage is supplied to both the VEHICLE STOP fuse and the VEHICLE CHMSL fuse. The current flow is now to the stop lamps which are grounded at G401 and G402. The center high mounted stop lamp (CHMSL) is grounded at G401.
For trailer wiring, a separate stop lamp circuit is connected through the GMSF to the trailer wiring harness.
Backup Lamps
On a vehicle equipped with an automatic transmission, the backup lamps request signal is sent from the powertrain control module (PCM) to the body control module (BCM) via class 2. This signal is based on the state of the park neutral position (PNP) switch. On a manual transmission equipped vehicle, the B/U fuse in the engine wiring harness junction block supplies battery positive voltage to the normally open backup lamp switch. When the driver places the gear selector lever is in the REVERSE position, the backup lamp switch closes and the current flow is from the backup lamp switch to the BCM signaling for backup lamp illumination.
The BCM directly supplies voltage for backup lamp operation on both automatic and manual transmission vehicles. The backup lamps are grounded at G401 and G402 (G305 on vehicles that have the backup lamps located in the lower bumper facia).
For trailer wiring, a separate backup lamp circuit is connected through the TRLR B/U fuse to the trailer wiring harness.
Interior Lamps
The interior lighting consist of the following 2 groups. This first group includes lamps that may not be dimmed.
- The cargo lamp
- The dome lamps
- The reading lamps
- The vanity mirror lamps
Courtesy Lamps
The courtesy lamps include the reading lamps, cargo lamp, and dome lamps. The cargo lamp and dome lamps may be manually turned ON or OFF by placing the interior lamp switch in the ON or OFF position. When the driver places the dome lamp defeat switch in the OFF position, these courtesy lamps will be disabled. If a door is opened, the courtesy lamps illuminate. After all the doors have been closed, the courtesy lamps will remain illuminated approximately 15 seconds after the last door closes. The courtesy lamps will also turn ON prior to any door being opened and will remain illuminated approximately 40 seconds when the driver removes the ignition key. The body control module (BCM) will immediately turn OFF the courtesy lamps if a door lock command is received with all of the doors closed, or if the ignition switch is turned to either the ON or RUN position.
Keyless Entry Interior Illumination
When the driver uses the door key in order to unlock the doors, the body control module (BCM) receives a door unlock signal. The BCM must have inputs that indicate that the ignition switch is OFF, the courtesy lamp switch is OFF, and all the doors are closed. The BCM will then illuminate the interior lamps. The courtesy lamps will remain illuminated for approximately 15 seconds after the door is closed. If the door locks are activated to the LOCK position, or if the ignition switch is turned to either the RUN or CRANK position, the courtesy lamps will turn OFF immediately.
When the driver uses the remote function actuator transmitter to unlock the doors or presses the panic button, the BCM will keep the courtesy lamps ON for approximately 15 seconds. If the door locks are activated to the UNLOCK or LOCK position or if the ignition switch is turned to either the RUN or CRANK position, the courtesy lamps will turn OFF immediately. The BCM will also keep the courtesy lamps ON for approximately 40 seconds after an alarm event is completed.
Vanity Mirror Lamps
The inadvertent power courtesy lamps supply voltage circuit of the body control module (BCM) provides battery positive voltage to each vanity mirror lamp. When the vanity mirror cover on the sunshade is opened, a switch closes to provide a ground circuit and the vanity lamp illuminates.
Battery Rundown Protection/Inadvertent Power
The body control module (BCM) inadvertent power courtesy lamps supply voltage circuit provides battery positive voltage to all of the interior reading lamps and both visor vanity mirror lamps. In the event that any of these lamps were to remain illuminated for a period of more than 20 minutes with the ignition switch in the OFF position, the BCM will deactivate the inadvertent power courtesy lamps supply voltage circuit to prevent a total battery discharge condition. Only when the ignition switch is cycled back to the RUN position will the BCM reset the internal timer and reactivate the inadvertent power courtesy lamps supply voltage circuit.
The BCM also utilizes the inadvertent power courtesy lamps supply voltage circuit as a courtesy lamp request signal circuit when none of the lamps in the circuit are illuminated. When a lamp switch is activated, the BCM receives the request for lamp illumination and switches to supplying voltage to the inadvertent power courtesy lamps supply voltage circuit.
Interior Lamps Dimming
The second group includes lamps which may be dimmed. This group may use a combination of vacuum fluorescent (VF) illumination and of incandescent lamps.
- Door switches and window switches
- HVAC control head assembly
- Radio and steering wheel controls
- The rear HVAC/radio controls
- The instrument panel cluster (IPC)
When the ignition switch is turned to the RUN position, the radio's VF displays turn ON at maximum brightness. When the park lamps are ON, all incandescent back lighting turn ON at the dimming level indicated by the instrument panel (I/P) dimmer switch. At the same time all VF displays dim to match the indicated dimming level. The panel dimmer switch potentiometer is an input to the body control module (BCM). When the driver selects a dimming setting by moving the I/P dimming switch potentiometer, all incandescent back lighting lamps are provided with a specific voltage. The incandescent back lighting lamps are then grounded at G201, G302, and G303. When the I/P dimmer switch is moved from MIN to MAX, all vacuum fluorescent (VF) displays, as well as all incandescent back lighting respond from minimum intensity to maximum brightness in response to the I/P dimmer switch.