Lighting System: Diagnosis Chevrolet Tahoe III

DIAGNOSTIC CODE INDEX

DIAGNOSTIC CODE INDEX

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Diagnostic Fault Information

Conditions for Running the DTC

1. Battery voltage must be between 9-16 V.
2. Ignition must be ON.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Dimming Control Signal parameter is less than 0.1 V. If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM.
4. Ignition ON, test for 12 V between the I/P dimming voltage reference circuit terminal 15 and ground. If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 15. Verify the scan tool BCM Dimming Control Signal parameter is greater than 2.6 V. If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
6. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery voltage must be between 9-16 V.
2. Front fog lamps ON.

Conditions for Setting the DTC

The BCM detects a short to voltage in the front fog lamp relay control circuit for 5 seconds or greater.

Actions Taken When the DTC Sets

The front fog lamps will not operate when the park lamps are ON and the front fog lamp switch is active.

Conditions for Clearing the DTC

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

1. Ignition OFF, disconnect the fog lamp relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the fog lamp relay.
4. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the appropriate fog lamp front.
6. Test for less than 5 ohms between the fog lamp front ground circuit terminal B and ground If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the fog lamp front.
8. Connect a 15 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the fog lamp front is activated. If the fog lamp front does not activate and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the fog lamp front. If the fog lamp front does not activate and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the fog lamp front.
9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Command the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
11. If all circuits test normal, test or replace the fog lamp relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery voltage must be between 9-16 V.
2. Rear fog lamps ON.

1. Ignition OFF, disconnect the harness connector at the headlamp switch.
2. Verify that a test lamp illuminates between B+ and the ground circuit terminal 8. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Rear Fog Lamp Switch parameter is INACTIVE. If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the XBCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 6 and ground. Verify the scan tool Rear Fog Lamp Switch parameter is ACTIVE. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the XBCM.
5. If all circuits test normal, test or replace the headlamp switch.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Battery voltage must be between 9-16 V.

The BCM detects a short to ground in the backup lamp relay control circuit.

Action Taken When the DTC Sets

The backup lamps will not operate.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
2. Connect a test lamp between the control circuit terminal 9 and ground.
3. Ignition ON, command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, connect the harness connector at the inside rearview mirror. Disconnect the X5 harness connector at the underhood fuse block.
5. Connect a test lamp between the control circuit terminal H8 and ground.
6. Ignition ON, command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
7. If all circuits test normal, replace the underhood fuse block.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery voltage must be between 9-16 V.
2. A message is sent from the BCM over the serial data circuit to the driver door and passenger door switches to active the door courtesy lamps.

Note. Each courtesy lighting component may need to be disconnected to isolate a short to voltage or short to ground. Use the schematic to identify the following: Courtesy lighting components the vehicle is equipped with. Component locations on the courtesy lighting control circuit Each component's control and ground circuit terminals

1. Ignition OFF, disconnect the harness connector at any component with inoperative courtesy lighting.
2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit and ground.
4. Command the Courtesy Lamp control ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, replace the component with the inoperative backlighting.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery voltage must be between 9-16 V.
2. Headlamps must be ON.

The BCM detects a short to voltage in the headlamp low beam relay control circuit.

The low beam headlamps will not operate.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

1. Ignition OFF, disconnect the low beam headlamp relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the low beam headlamp relay.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the appropriate head lamp.
6. Test for less than 5 ohms between the head lamp ground circuit terminal listed below and ground: With X88 - Terminal A With Z88 - Terminal B If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the headlamp.
8. Connect a 20 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the headlamp is activated. If the headlamp does not activate and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the headlamp. If the headlamp does not activate and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the headlamp.
9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
11. If all circuits test normal, test or replace the low beam headlamp relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Battery voltage must be between 9-16 V

The BCM detects a short to ground on the headlamp switch headlamps OFF signal circuit or the headlamp switch headlamps ON signal circuit.

1. The low beam headlamps are always ON in the AUTO position. The headlamp switch operates in all positions other than AUTO. The AUTO headlamp defeat is inoperative.
2. The low beam headlamps are always ON. The BCM disregards all headlamp switch inputs.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

1. Ignition OFF, disconnect the X2 harness connector at the BCM.
2. Connect a test lamp between B+ and the signal circuit terminal 17.
3. Turn the headlamp switch between the AUTO and AUTO disable positions. The test lamp should turn ON and OFF as the switch is cycled. If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit test normal, replace the headlamp and panel dimmer switch. If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit test normal, replace the headlamp and panel dimmer switch.
4. Connect a test lamp between B+ and the signal circuit terminal 3.
5. Turn the headlamp switch to the ON and OFF positions. The test lamp should turn ON and OFF as the switch is cycled. If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit test normal, replace the headlamp and panel dimmer switch. If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit test normal, replace the headlamp and panel dimmer switch.
6. If all circuits test normal, replace the BCM.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery voltage must be between 9-16 V.
2. Headlamps ON.

The BCM detects a short to voltage in the headlamp HIGH BEAM relay control circuit.

The high beam headlamps and flash to pass (FTP) will not operate.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

1. Ignition OFF, disconnect the X4 harness connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal C3 and B+.
3. Command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or open/high resistance. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, test or replace the underhood fuse block.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. The Ignition is ON.
2. The park lamps must be commanded ON by the BCM.

The BCM detects a short to voltage on the park lamp relay control circuit.

All park, license, and tail lamps are inoperative.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The BCM receives the clear code command from the scan tool.

1. Ignition OFF, disconnect the park lamp relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 86 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the fog lamp relay.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the appropriate park lamp.
6. Test for less than 5 ohms between the park lamp ground circuit terminal and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the park lamp.
8. Connect a 15 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the park lamp is activated. If the park lamp does not activate and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the park lamp. If the park lamp does not activate and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the park lamp.
9. Connect a test lamp between the B+ circuit terminal 86 and the control circuit terminal 85.
10. Command the Parking Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
11. If all circuits test normal, test or replace the park lamp relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery voltage must be between 9-16 V.
2. Headlamp switch in AUTO position.

The BCM detects a short to voltage in the DRL relay control circuit.

The BCM will disable the DRL relay control circuit.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

1. Ignition OFF, disconnect the X4 harness connector at the fuse block - underhood.
2. Connect a test lamp between the control circuit terminal H4 and B+.
3. Command the DRLs ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, connect the X4 harness connector at the fuse block - underhood. Disconnect the harness connector at the daytime running lamp.
5. Test for less than 5 ohms between the daytime running lamp ground circuit terminal listed below and ground: With X88 - Terminal C With Z75 and Z88 - Terminal B If greater than the specified range, test the ground circuit for an open/high resistance.
6. Connect a test lamp between control circuit terminal A and ground
7. Command the DRLs ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the fuse block - underhood. If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the fuse block - underhood. If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the daytime running lamp.
8. If all circuits test normal, test or replace the daytime running lamp.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery voltage must be between 9-16 V.
2. Headlamp switch in AUTO position.

The BCM detects a short to voltage in the DRL resistor control circuit.

1. The Service Headlamp Assembly indicator is commanded ON.
2. The BCM will disable the DRL resistor control circuit.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

1. Ignition OFF, disconnect the harness connector at the DRL resistor.
2. Connect a test lamp between the control circuit terminal C and B+.
3. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, connect the harness connector at the DRL resistor.
5. Disconnect the harness connector at the inoperative headlamp assembly.
6. Connect a test lamp between the signal circuit terminal D and B+.
7. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit tests normal, replace the DRL resistor. If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the DRL resistor.
8. Connect a test lamp between the signal circuit terminal B and B+.
9. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit tests normal, replace the DRL resistor. If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the DRL resistor.
10. If all circuits test normal, replace the appropriate headlamp.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery Voltage be between 9-16 V.
2. The ignition is ON.

The BCM, driver door switch, and passenger door switch detect a short to voltage, short to ground, or an open on the LED dimming supply circuit.

The BCM, driver door switch, and passenger door switch will cease attempts to dim or illuminate the LED lamps.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The BCM receives the clear code command from the scan tool.

Note. Each back lighted component may need to be disconnected to isolate a short to voltage or short to ground. Use the schematic to identify the following: Back lighted components the vehicle is equipped with. Component locations on the back lighting dimming control circuit Each component's control and ground circuit terminals

1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit and ground.
4. Command the Incandescent Dimming Control ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, replace the component with the inoperative backlighting.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery Voltage must be between 9-16 V.
2. The ignition is ON.
3. The BCM, driver door switch, and passenger door switch attempt to illuminate the courtesy lamps.

The BCM, driver door switch, or passenger door switch detect a short to ground, short to voltage, or open on the courtesy lamp voltage supply circuit.

The BCM, driver door switch, and passenger door switch cease attempts to illuminate the courtesy lamps.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The BCM receives the clear code command from the scan tool.

Note. Each courtesy lighting component may need to be disconnected to isolate a short to voltage or short to ground. Use the schematic to identify the following: Courtesy Lighting components the vehicle is equipped with. Component locations on the courtesy lighting control circuit Each component's control and ground circuit terminals

1. Ignition OFF, disconnect the harness connector at any component with inoperative courtesy lighting.
2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit and ground.
4. Command the Courtesy Lamp control ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, replace the component with the inoperative courtesy lighting.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

The ignition is ON.

The BCM receives a ground signal on the LED indicator dimming supply circuit.

The BCM cease attempt to dim or illuminate the LED indicator lamps.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The BCM receives the clear code command from the scan tool.

Note. Each LED dimming lighting component may need to be disconnected to isolate a short to voltage or short to ground. Use the schematic to identify the following: LED dimming lighting components the vehicle is equipped with. Component locations on the LED dimming control circuit Each component's control and ground circuit terminals

1. Ignition OFF, disconnect the harness connector at any component with inoperative LED dimming lighting.
2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit and ground.
4. Command the LED Dimming Control ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, replace the component with the inoperative LED dimming lighting.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Battery voltage must be between 9-16 V.

1. Ignition OFF, disconnect the harness connector at the ambient light sensor.
2. Test for less than 5.0 ohms between the ground circuit listed below and ground. Ambient Light Sensor terminal C - CJ2 Ambient Light Sensor terminal B - w/o CJ2 If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.5 V. If less than the specified range, test the signal circuit for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal listed below and the low reference circuit terminal listed below. Verify the scan tool Ambient Light Sensor parameter is less than 1.0 V. Ambient Light Sensor terminals A to B - w/o CJ2 Ambient Light Sensor terminals D to C - CJ2 If greater than the specified range, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the ambient light sensor.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery voltage must be between 9-16 V.
2. The ignition must be ON.

The BCM receives an open, voltage, or ground signal on the I/P lamp dimming control circuit.

The I/P lamps are not illuminated.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The BCM receives the clear code command from the scan tool.

1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit and ground.
4. Command the Incandescent Dimming Control ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, replace the component with the inoperative backlighting.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Battery voltage must be between 9-16 V.
2. Brakes APPLIED.

The BCM detects a short to ground in the CHMSL control circuit when the stop lamps are being commanded ON.

The BCM will not illuminate the CHMSL.

1. The condition responsible for setting the DTC no longer exists.
2. A history DTC will clear once 100 malfunction-free ignition cycles have occurred.

1. Ignition OFF, disconnect the harness connector at the center high mounted stop lamp.
2. Test for less than 5.0 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal A and the ground circuit terminal B.
4. Ignition ON, turn the stop lamps ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the selected states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, replace the center high mounted stop lamp.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

System voltage to the XBCM must be 9-16 V.

The rear fog lamp switch signal circuit is active for longer than 10 minutes.

The rear fog lamps will be disabled.

1. The DTC will be current for as long as the fault is present.
2. When the fault is no longer present, the DTC will be a history status code.
3. A history DTC will clear after 50 ignition cycles or with a scan tool using the clear DTCs function.

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition OFF, verify a test lamp illuminates between B+ and the ground circuit terminal 8. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Verify the scan tool Rear Fog Lamp Switch parameter displays Inactive. If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the XBCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 6 and the ground circuit terminal 8. Verify the scan tool Rear Fog Lamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the XBCM.
5. If all circuits test normal, replace the headlamp and panel dimmer switch.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

The ignition is ON.

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Dimming Control Signal parameter is less than 0.1 V. If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM.
4. Ignition ON, test for 12 V between the I/P dimming voltage reference circuit terminal 15 and ground. If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 15. Verify the scan tool BCM Dimming Control Signal parameter is greater than 2.6 V. If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
6. If all circuits test normal, test or replace the headlamp switch.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. The ignition is ON.
2. The stop lamps must be commanded ON.

The BCM detects a short to ground in the CHMSL supply voltage circuit when the stop lamps are commanded ON.

The CHMSL will not illuminate.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The BCM receives the clear code command from the scan tool.

1. Ignition OFF, disconnect the harness connector at the center high mounted stop lamp.
2. Test for less than 5.0 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the stop lamp control circuit terminal A and ground circuit terminal B.
4. Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the center high mounted stop lamp.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

The ignition is ON. Park lamps must be ON and the rear fog lamps must be commanded ON.

The body control module (BCM) detects an open, short to ground, or short to voltage on the trailer rear fog lamp circuit while trying to apply a voltage to the circuit.

The trailer rear fog lamps do not illuminate.

1. The conditions for setting the DTC are no longer present.
2. A history DTC clears after 100 malfunction-free ignition cycles.
3. The BCM receives the clear code command from the scan tool.

1. Inspect the trailer rear fog lamp bulb for an open or shorted filament. If the bulb is inoperable, replace the bulb.
2. Park lamp switch OFF, clear the DTC, test the trailer rear fog lamp circuit for a short to voltage, short to ground, an open, or high resistance. If all circuits/connections test normal, replace the XBCM.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Battery voltage must be between 9-16 V.

In the event that DTC C0277, C0297, or C0890 sets as current in the body control module (BCM) is an indication of a possible internal BCM malfunction or programming error. There are no external circuits available to diagnose on this vehicle with respect to these DTCs.

When DTC C0277 is set as current, the vehicle may not start.

1. For DTC C0277 the ignition must be cycled before the code can be cleared.
2. A history DTC will clear once 50 malfunction-free ignition cycles have occurred.
3. A DTC will not clear the current status until the next ignition cycle.

Diagnostic Aids

These DTCs may set as current after the replacement of an electronic brake control module (EBCM) or engine control module (ECM). If a control module has been replaced, ensure that the programming procedure and all recalibration procedures have been completed successfully before addressing these DTCs.

Visual/Physical Inspection

1. Inspect for aftermarket devices which could affect the operation of the Lighting System. Refer to «Checking Aftermarket Accessories»(ref-364488-S07680217832010063000000) .
2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

1. «Backup Lamps Malfunction»(ref-364469-S07190794152010063000000)
2. «Courtesy Lamps Malfunction»(ref-364469-S03078659722010063000000)
3. «Daytime Running Lamps Malfunction (With Z88, Z75, and Z88)»(ref-364469-S02062909342010063000000) or «Daytime Running Lamps Malfunction (With T4Q)»(ref-364469-S42811772062010063000000)
4. «Door Sill Illumination Malfunction»(ref-364469-S02544685772010063000000)
5. «Front Fog Lamps Malfunction»(ref-364469-S27645743672010063000000)
6. «Rear Fog Lamps Malfunction»(ref-364469-S17713108882010063000000)
7. «Hazard Lamps Malfunction»(ref-364469-S15000349022010063000000)
8. «Headlamps Malfunction (With X88, Z75, and Z88)»(ref-364469-S04443585362010063000000) or «Headlamps Malfunction (With T4Q)»(ref-364469-S07038295262010063000000)
9. «High Intensity Discharge Lamp Malfunction»(ref-364469-S41260775872010063000000)
10. «Interior Backlighting Malfunction»(ref-364469-S37554264762010063000000)
11. «Park, License, and/or Tail Lamps Malfunction (With X88, Z75, and Z88)»(ref-364469-S20552720422010063000000) or «Park, License, and/or Tail Lamps Malfunction (Front LED Park/Marker Lamps with T4Q)»(ref-364469-S32728644072010063000000)
12. «Stop Lamps Malfunction»(ref-364469-S03881937552010063000000)
13. «Turn Signal Lamps and/or Indicators Malfunction»(ref-364469-S39966378562010063000000)

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Ignition OFF, disconnect the harness connector at the inside rearview mirror.
2. Connect a test lamp between the control circuit terminal 9 and ground.
3. Ignition ON, command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Connect the harness connector at the inside rearview mirror.
5. Ignition OFF, disconnect the harness connector X5 at the BCM.
6. Connect a test lamp between the control circuit terminal 7 and ground.
7. Ignition ON, command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
8. Ignition OFF, disconnect the harness connector at the inoperative backup lamp.
9. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms between the ground circuit terminal listed below and ground: With HP2 - Terminal B With X88 - Terminal A With Z75 - E52 - Terminal GRD With Z88 - Terminal 1 If greater than the specified range, test the ground circuit for an open/high resistance.
10. Connect a test lamp between the control circuit terminal listed below and ground: With HP2 - Terminal B With X88 - Terminal A With Z75 - E52 - Terminal GRD With Z88 - Terminal 1
11. Ignition ON, command the Backup Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
12. If all circuits test normal, test or replace the inoperative backup lamp.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Courtesy Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate lamp.
2. Test for less than 5.0 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal listed below and the ground. Courtesy/Reading Lamp terminal A Dome/Reading Lamp terminal C Door Courtesy Lamp terminal A Sunshade Lamps terminal A Dome Lamp terminal A Cargo Lamp terminal A
4. Ignition ON, command the Courtesy Lamps output control ON and OFF with the scan tool. The test lamp should turn ON and OFF. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the courtesy lamp.

Dome/Interior Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Test for less than 5.0 ohms between the ground circuit terminal 8 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Ctsy. Lamp Actv. Reason parameter is Off. If the parameter is Manual or Manual Defeat, test the appropriate signal circuit terminal for a short to ground. If the circuit tests normal, replace the BCM. Manual terminal 12 Manual Defeat terminal 9
4. Install a 3 A fused jumper wire between the signal circuit terminal 12 and the ground circuit terminal 8. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 9 and the ground circuit terminal 8. Verify the scan tool Ctsy. Lamp Actv. Reason parameter is Manual Defeat. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
6. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Reading Lamps Malfunction

1. Ignition OFF, disconnect the X3 harness connector at the BCM.
2. Verify a test lamp illuminates between the IS LPS fuse B+ circuit terminal 2 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
3. Reconnect the X3 harness connector at the BCM.
4. Disconnect the harness connector at the inoperative courtesy/reading lamp assembly.
5. Scan tool OFF, doors CLOSED, interior lamps OFF, test for less than 5.0 ohms between the ground circuit terminal B and ground.
6. Verify a test lamp illuminates between the control circuit terminal listed below and ground: Courtesy/Reading Lamp terminal C Dome/Reading Lamp terminal A If the test lamp does not illuminate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
7. Remove the IS LPS fuse and verify the test lamp turns OFF. If the test lamp remains illuminated, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
8. If all circuits test normal, replace the courtesy lamp assembly.

Vanity Mirror Lighting Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate vanity mirror lamp.
2. Test for less than 5.0 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify that a test lamp illuminates between the control circuit terminal A and ground. If the test lamp does not illuminate, test the inadvertent power supply circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Connect the harness connector at the vanity mirror lamp.
5. Remove the IS LPS fuse and verify the test lamp turns OFF. If the test lamp remains illuminated, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
6. If all circuits test normal, replace the vanity mirror.

Outside Rearview Mirror Illumination Malfunction

1. Disconnect the harness connector at the appropriate exterior illumination lamp.
2. Ignition ON, verify that a test lamp illuminates between the exterior illumination lamp supply circuit terminal and ground. If the test lamp does not illuminate, test the exterior illumination lamp supply circuit for a short to ground or an open/high resistance.
3. Connect a test lamp between the low side control circuit terminal and the exterior illumination lamp supply circuit terminal.
4. Command the Courtesy Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the inoperative door switch. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the inoperative door switch.
5. If all circuits test normal, test or replace the appropriate lamp.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Note. This diagnostic procedure assumes that the low beam headlamps are operating within specifications. If the low beam headlamps are inoperative, diagnose the low beam headlamp malfunction before proceeding with the following diagnostic.

Daytime Running Lamp Malfunction - with Z75/X88

1. Ignition OFF, disconnect the harness connector X4 at the underhood fuse block.
2. Connect a test lamp between the daytime running lamps relay control circuit terminal H4 and B+.
3. Ignition ON, command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, reconnect the harness connector X4 at the underhood fuse block.
5. Disconnect the harness connector at the appropriate daytime running lamp.
6. Test for less then 5 ohms between the ground circuit listed below and ground. Terminal B (Z75) Terminal C (X88) If less than the specified range, test the ground circuit for an open/high resistance.
7. Ignition OFF, connect a test lamp between the control circuit terminal A and ground.
8. Ignition ON, command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF. If the test lamp is always ON, test the control circuit for a short to voltage. If the control circuit tests normal, replace the underhood fuse block. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, and the DRL fuse is not open, replace the underhood fuse block.
9. If all circuits test normal, replace the daytime running lamp.

Daytime Running Lamp Malfunction - with Z88

1. Ignition OFF, disconnect the harness connector X4 at the underhood fuse block.
2. Connect a test lamp between the daytime running lamps relay control circuit terminal H4 and B+.
3. Ignition ON, command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, reconnect the harness connector X4 at the underhood fuse block.
5. Disconnect the harness connector at the appropriate headlamp.
6. Test for less then 5 ohms between the ground circuit terminal B and ground. If more than the specified range, test the ground circuit for an open/high resistance.
7. Ignition OFF, connect a test lamp between the control circuit terminal A and ground.
8. Ignition ON, command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF. If the test lamp is always ON, test the control circuit for a short to voltage. If the control circuit tests normal, replace the underhood fuse block. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, and the DRL fuses are not open, replace the underhood fuse block.
9. If all circuits test normal, replace the headlamp.

Ambient Light Sensor Malfunction

1. Ignition OFF, disconnect the harness connector at the ambient light sensor.
2. Ignition OFF, test for less than 5 ohms between the ground circuit terminal listed below and ground. Terminal C (with CJ2) Terminal B (without CJ2) If greater than the specific range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.65 V. If less than the specified range, test the signal circuit terminal for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal listed below and the ground circuit terminal. Verify the scan tool Ambient Light Sensor parameter is less than 0.196 V. Terminal D (with CJ2) Terminal A (without CJ2) If greater than the specified range, test the signal circuit for a short to voltage an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, replace the ambient light sensor.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Note. This diagnostic procedure assumes that the low beam headlamps are operating within specifications. If the low beam headlamps are inoperative, diagnose the low beam headlamp malfunction before proceeding with the following diagnostic.

Daytime Running Lamp Malfunction

1. Ignition OFF, disconnect the harness connector at the DRL resistor.
2. Connect a test lamp between the control circuit terminal C and B+.
3. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, connect the harness connector at the DRL resistor.
5. Disconnect the harness connector at the appropriate headlamp assembly.
6. Connect a test lamp between the signal circuit terminal D and B+.
7. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit tests normal, replace the DRL resistor. If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the DRL resistor.
8. Connect a test lamp between the signal circuit terminal B and B+.
9. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the signal circuit for a short to ground. If the circuit tests normal, replace the DRL resistor. If the test lamp is always OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the DRL resistor.
10. If all circuits test normal, replace the headlamp assembly.

Ambient Light Sensor Malfunction

1. Ignition OFF, disconnect the harness connector at the ambient light sensor.
2. Ignition OFF, test for less than 5 ohms between the ground circuit terminal listed below and ground. Terminal C (with CJ2) Terminal B (without CJ2) If greater than the specific range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Ambient Light Sensor parameter is greater than 4.65 V. If less than the specified range, test the signal circuit terminal for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal listed below and the ground circuit terminal. Verify the scan tool Ambient Light Sensor parameter is less than 0.196 V. Terminal D (with CJ2) Terminal A (without CJ2) If greater than the specified range, test the signal circuit for a short to voltage an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, replace the ambient light sensor.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Ignition OFF, verify door sill plate lamp ground circuit 1150 is securely connected to the driver side kick panel ground stud. If the door sill plate lamp ground circuit is not securely connected, repair the poor connection.
2. Disconnect the X2 (blue) harness connector at the BCM.
3. Using the appropriate test tool, connect a test lamp between the control circuit terminal 5 at the BCM and ground.
4. Ignition ON, turn the door sill plate lamp ON and OFF by opening and closing the vehicle door. The test lamp should turn ON and OFF when changing between the selected states. If the test lamp is always ON or OFF, replace the BCM.
5. If all circuits test normal, replace the door sill plate lamp kit.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Front Fog Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition OFF, verify a test lamp illuminates between B+ and the ground circuit terminal 8. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Front Fog Lamp Switch parameter is INACTIVE. If not the specified value, test the signal circuit terminal 10 for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 10 and the ground circuit terminal 8. Verify the scan tool Front Fog Lamp Switch parameter is ACTIVE. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Front Fog Lamps Malfunction

1. Ignition OFF, disconnect the front fog lamp relay.
2. Ignition ON, verify a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify a test lamp illuminates between the B+ circuit terminal 85 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the appropriate front fog lamp.
6. Ignition OFF, test for less than 5.0 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the front fog lamp.
8. Connect a 15 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the front fog lamps are activated. If the front fog lamps do not activate, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the front fog lamp.
9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Ignition ON, command the Fog Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or open/high resistance. If the circuit tests normal, replace the BCM.
11. If all circuits test normal, test or replace the front fog lamp relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Rear Fog Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Test for less than 1 ohms between the ground circuit terminal 8 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Rear Fog Lamp Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 6 for a short to ground. If the circuit tests normal, replace the XBCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 6 and the ground circuit terminal 8. Verify the scan tool Rear Fog Lamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the XBCM.
5. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Rear Fog Lamps Malfunction

1. Ignition OFF, disconnect the harness connector at the rear fog lamp.
2. Test for less than 1 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit terminal A and the ground circuit terminal B.
4. Command the Rear Fog Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the XBCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the XBCM.
5. If all circuits test normal, test or replace the rear fog lamp.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

1. Ignition OFF, disconnect the harness connector X1 at the turn signal/multifunction switch.
2. Test for less than 1 ohms between the ground circuit terminal C and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Hazard Lamp Switch parameter is Inactive. If not the specified value, test the signal circuit terminal G for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal G and the ground circuit terminal C. Verify the scan tool Hazard Lamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the turn signal/multifunction switch

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

The following symptoms are noticeable signs of bulb failure

1. Lights go out, caused when the ballast detects excessive, repetitive bulb re-strike.
2. Color change-The lamp may change to a dim pink glow.

1. Ignition OFF, disconnect the HDLP LO/HID Relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 86 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the inoperative headlamp.
6. Test for less than 5 ohms between the headlamp ground circuit terminal 2 and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the headlamp.
8. Connect a 20 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the headlamp - low beam is activated. If the headlamp - low beam does not activate and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the headlamp. If the headlamp - low beam does not activate and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the headlamp.
9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace BCM.
11. If all circuits test normal, test or replace the HDLP LO/HID Relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Headlamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 8. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Headlamp Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the BCM.
4. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Inactive. If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the BCM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Headlamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
6. Install a 3 A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Active. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
7. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Turn Signal/Multifunction Switch Malfunction

1. Ignition OFF, disconnect the X2 harness connector at the turn signal/multifunction switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal D. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Flash to Pass Switch parameter is Inactive. If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the BCM.
4. Verify the scan tool High Beam Select Switch parameter is Inactive. If not the specified value, test the signal circuit terminal E for a short to ground. If the circuit tests normal, replace the BCM.
5. Install a 3 A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Flash to Pass Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
6. Install a 3 A fused jumper wire between the signal circuit terminal E and ground. Verify the scan tool High Beam Select Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
7. If all circuits test normal, test or replace the turn signal/multifunction switch.

Headlamps Malfunction - Low Beam (with X88, Z88 and Z75)

1. Ignition OFF, disconnect the HDLP LO/HID relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the appropriate headlamp.
6. Test for less than 5 ohms between the headlamp ground circuit terminal listed below and ground: RPO X88 - terminal A RPO Z88 - terminal B RPO Z75 - terminal 2 If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the headlamp.
8. Connect a 20 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the headlamp - low beam is activated. If the headlamp - low beam does not activate and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the headlamp. If the headlamp - low beam does not activate and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the headlamp.
9. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
10. Command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
11. If all circuits test normal, test or replace the HDLP LO/HID relay.

Headlamps Malfunction - Daytime Running Lamps (with X88 and Z75)

1. Ignition OFF, disconnect the X4 harness connector at the fuse block - underhood.
2. Connect a test lamp between the control circuit terminal H4 and B+.
3. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, connect the X4 harness connector at the fuse block - underhood. Disconnect the harness connector at the appropriate daytime running lamp.
5. Test for less than 5 ohms between the daytime running lamp ground circuit terminal listed below and ground: RPO X88 - terminal C RPO Z75 - terminal B If greater than the specified range, test the ground circuit for an open/high resistance.
6. Connect a test lamp between the control circuit terminal A and ground.
7. Command the DRL ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the fuse block - underhood. If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the fuse block - underhood. If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the daytime running lamp.
8. If all circuits test normal, test or replace the daytime running lamp.

Headlamps Malfunction - High Beam (with X88, Z88 and Z75)

1. Ignition OFF, disconnect the X4 harness connector at the fuse block - underhood.
2. Connect a test lamp between the control circuit terminal C3 and B+.
3. Command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, connect the X4 harness connector at the fuse block - underhood. Disconnect the harness connector at the appropriate headlamp.
5. Test for less than 5 ohms between the headlamp ground circuit terminal listed below and ground: RPO X88 - terminal A RPO Z88 - terminal B RPO Z75 - terminal 1 If greater than the specified range, test the ground circuit for an open/high resistance.
6. Connect a test lamp between the control circuit terminal listed below and ground: RPO X88 - terminal B RPO Z88 - terminal C RPO Z75 - terminal 2
7. Command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the fuse block - underhood. If the test lamp is always OFF and the circuit fuse is good, test the control circuit for an open/high resistance. If the circuit tests normal, test or replace the fuse block - underhood. If the test lamp is always OFF and the circuit fuse is open, test the control circuit for a short to ground. If the circuit tests normal, test or replace the headlamp.
8. If all circuits test normal, test or replace the headlamp.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

The headlamp outage detection circuits are low current B+ circuits supplied by the BCM. For purposes of testing, a test lamp connected between the outage detection circuit and ground will not illuminate due to low current.

Headlamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 8. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Headlamp Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the BCM.
4. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Inactive. If not the specified value, test the signal circuit terminal 3 for a short to ground. If the circuit tests normal, replace the BCM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground. Verify the scan tool Headlamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
6. Install a 3 A fused jumper wire between the signal circuit terminal 3 and ground. Verify the scan tool Auto Hdlp. Disable Sw. parameter is Active. If not the specified value, test the signal circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the BCM.
7. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Turn Signal/Multifunction Switch Malfunction

1. Ignition OFF, disconnect the X2 harness connector at the turn signal/multifunction switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal D. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Flash to Pass Switch parameter is Inactive. If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the BCM.
4. Verify the scan tool High Beam Select Switch parameter is Inactive. If not the specified value, test the signal circuit terminal E for a short to ground. If the circuit tests normal, replace the BCM.
5. Install a 3 A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool Flash to Pass Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
6. Install a 3 A fused jumper wire between the signal circuit terminal E and ground. Verify the scan tool High Beam Select Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
7. If all circuits test normal, test or replace the turn signal/multifunction switch.

Headlamps Malfunction - Low Beam

1. Ignition OFF, disconnect the HDLP LO/HID relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 85 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Connect a test lamp between the B+ circuit terminal 85 and the control circuit terminal 86.
6. Command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
7. Ignition OFF, connect the HDLP LO/HID relay.
8. Disconnect the harness connector at the appropriate headlamp.
9. Ignition OFF, scan tool OFF, exterior lamps OFF, test for less than 5.0 ohms between each ground circuit terminal listed below and ground. Ground circuit terminal F Ground circuit terminal M If greater than the specified range, test the ground circuit for an open/high resistance.
10. Connect a test lamp between the control circuit terminal A and ground.
11. Command the Low Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the HDLP LO/HID relay. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the HDLP LO/HID relay.
12. Ignition OFF, connect the harness connector at the headlamp.
13. Command the Low Beams ON and OFF with a scan tool. The low beam headlamp should turn ON and OFF when changing between the commanded states. If all of the low beam LED's do not illuminate, replace the headlamp control module. If some of the low beam LEDs illuminate, replace the headlamp assembly.

Headlamps Malfunction - High Beam

1. Ignition OFF, disconnect the X4 connector at the underhood fuse block.
2. Connect a test lamp between the control circuit terminal C3 and B+.
3. Ignition ON, command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Ignition OFF, disconnect the harness connector at the appropriate headlamp.
5. Ignition OFF, scan tool OFF, exterior lamps OFF, test for less than 5.0 ohms between each ground circuit terminal listed below and ground. Ground circuit terminal F Ground circuit terminal M If greater than the specified range, test the ground circuit for an open/high resistance.
6. Connect a test lamp between the control circuit terminal L and ground.
7. Command the High Beams ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the underhood fuse block. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the underhood fuse block.
8. Ignition OFF, connect the harness connector at the headlamp.
9. Command the High Beams ON and OFF with a scan tool. The high beam headlamp should turn ON and OFF when changing between the commanded states. If all of the high beam LED's do not illuminate, replace the headlamp control module. If some of the high beam LEDs illuminate, replace the headlamp assembly.

Headlamp Outage Detection Malfunction

1. Ignition OFF, disconnect the harness connector at the appropriate headlamp assembly.
2. Ignition ON, test for B+ between the signal circuit terminal C and ground. If less than the specified value, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
3. Ignition ON, verify that a test lamp does not illuminate between the signal circuit terminal C and ground. If the test lamp illuminates, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
4. If all circuits test normal, test or replace the headlamp control module.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Dimmer Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition OFF, verify that a test lamp illuminates between the ground circuit terminal 8 and B+. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Dimming Control Signal parameter is less than 0.1 V. If greater than the specified range, test the signal circuit terminal 13 for a short to voltage. If the circuit tests normal, replace the BCM.
4. Ignition ON, test for B+ between the I/P dimming voltage reference circuit terminal 15 and ground. If less than the specified value, test the voltage reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
5. Install a 3 A fused jumper wire between the signal circuit terminal 13 and the voltage reference circuit terminal 15. Verify the scan tool BCM Dimming Control Signal parameter is greater than 2.6 V. If less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
6. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Interior Backlighting Malfunction

1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohms between the ground circuit and ground. If greater than the specified value, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the control circuit and ground.
4. Command the Incandescent Dimming or LED Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the component with the inoperative backlighting.

Front Door Switch Backlighting Malfunction

1. Ignition OFF, disconnect the harness connector X4 at the door lock and side window switch.
2. Connect a 3 A fused jumper wire between the low reference circuit terminal 4 and ground.
3. Connect a test lamp between the backlight supply voltage circuit terminal 13 and B+. The heated seat switch backlighting should illuminate. If the switch backlighting does not illuminate, replace the heated seat switch.
4. If the switch backlighting tests normal, replace the door lock and side window switch.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Park Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 8. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Park Lamp Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Park Lamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Park, License, and/or Tail Lamps Malfunction

1. Ignition OFF, disconnect the park lamp relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 86 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the park lamp relay.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the appropriate park/license/marker lamp.
6. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the appropriate ground circuit terminal listed below and ground. Park/Turn Signal Lamp - Left or Right front terminal C - with X88 Park/Turn Signal Lamp - Left or Right front terminal G - with Z88 Marker Lamp - Left or Right front terminal A - with Z75 Marker Lamp - Left or Right front terminal B - with Z88 or X88 Park Lamp - Left or Right front terminal B - Z75 Tail/Stop and Turn Signal Lamp - Lower Left or Right rear terminal G - w/o X88 - E52 Tail/Stop and Turn Signal Lamp - Upper Left or Right rear terminal GND - with X88 - E52 Tail/Turn Signal Lamp - Left or Right terminal G - w/o X88 + E52 Tail/Turn Signal Lamp - Left or Right terminal GND - with X88 + E52 Tail/Stop Lamp - Left or Right Rear terminal G - w/o X88 + E52 Tail/Stop Lamp - Left or Right Rear terminal GND - w/o X88 + E52 Marker Lamp - Left or Right Rear terminal B - with Z88 Marker Lamp - Left or Right Rear terminal A - with Z75 or X88 - E52 Tail Lamp Circuit Board - Left or Right Rear terminal D - with Z75 + E52 License lamp terminal B If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the park/license/marker lamp.
8. Connect a 15 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the park/marker lamps illuminate. If the park/marker lamps do not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the inoperative park/license/marker lamp.
9. Connect a test lamp between the control circuit terminal 85 and B+ circuit terminal 86.
10. Command the Parking Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
11. If all circuits test normal, test or replace the park lamp relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Park Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the headlamp and panel dimmer switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 8. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Park Lamp Switch parameter is Inactive. If not the specified value, test the signal circuit terminal 2 for a short to ground. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal 2 and ground. Verify the scan tool Park Lamp Switch parameter is Active. If not the specified value, test the signal circuit for a short to voltage or open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the headlamp and panel dimmer switch.

Park, License, and/or Tail Lamps Malfunction

1. Ignition OFF, disconnect the park lamp relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 86 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the park lamp relay.
4. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the appropriate park/license/marker lamp.
6. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the appropriate ground circuit terminal listed below and ground. Headlamp - Left or Right terminal J Tail Lamp Circuit Board - Left or Right Rear terminal D - with Z75 + E52 License lamp terminal B If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the park/license/marker lamp.
8. Connect a 15 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the park/marker lamps illuminate. If the park/marker lamps do not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the park/license/marker lamp.
9. Connect a test lamp between the control circuit terminal 85 and B+ circuit terminal 86.
10. Command the Parking Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
11. If all circuits test normal, test or replace the park lamp relay.

Front LED Park Lamps Malfunction

1. Ignition OFF, disconnect the PRK LAMP relay.
2. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 87 and ground. If the test lamp illuminates, test the control circuit for a short to voltage.
3. Verify that a test lamp illuminates between the B+ circuit terminal 30 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuit terminal 87 for a short to ground. If the circuit tests normal, test or replace the park lamp relay.
4. Verify that a test lamp illuminates between the B+ circuit terminal 86 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
5. Disconnect the harness connector at the inoperative headlamp/park lamp assembly.
6. Ignition OFF, exterior lamps OFF, test for less than 5 ohms between the ground circuit terminal J and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect the harness connector at the inoperative headlamp/park lamp assembly.
8. Connect a 20 A fused jumper wire between the B+ circuit terminal 30 and the control circuit terminal 87. Verify the marker lamps illuminate. If all of the front park/marker lamp LEDs do not illuminate, test the control circuit for an open/high resistance. If the circuit tests normal, replace the headlamp control module. If some of the front park/marker lamp LEDs illuminate, replace the appropriate headlamp assembly.
9. Connect a test lamp between the control circuit terminal 85 and B+ circuit terminal 86.
10. Command the Park Lamps ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to ground. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
11. If all circuits test normal, test or replace the park lamp relay.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Stop Lamp Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the stop lamp switch.
2. Ignition ON, test for battery voltage between the 12 V reference circuit terminal C and ground. If less than the specified range, test the 12 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
3. Verify the scan tool Stop Lamp Switch Status parameter is approximately 1023 counts. If not the specified value, test the signal circuit terminal D for a short to voltage. If the circuit tests normal, replace the BCM.
4. Install a 3 A fused jumper wire between the signal circuit terminal D and the 12 V reference circuit terminal C. Verify the scan tool Stop Lamp Switch Status parameter is 1 count. If not the specified value, test the signal circuit for an open/high resistance. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, test or replace the stop lamp switch.

Stop Lamp Malfunction

1. Ignition OFF, disconnect the harness connector X4 at the BCM.
2. Ignition ON, verify a test lamp illuminates between the stop lamp B+ terminal 4 and ground. If the test lamp does not illuminate, and the STOP LAMPS fuse tests normal, test the B+ circuit for a short to ground or an open/high resistance.
3. Connect the harness connector X4 at the BCM.
4. Ignition OFF, disconnect the harness connector at the appropriate stop lamp.
5. Test for less than 5.0 ohms between the listed ground circuit terminal below and ground. Tail/Stop and Turn Signal Lamp - Left and Right - Upper and Lower terminal GRD - with Z75 - E52 Tail Lamp Circuit Board - Left and Right terminal D - with Z75 + E52 and European Tail/Stop Lamp - Left and Right terminal GRD - with X88 Tail/Stop Lamp - Left and Right terminal G - Z88 Tail/Stop Lamp - Left and Right terminal 2 - with HP2 If greater than the specified range, test the ground circuit for an open/high resistance.
6. Connect a test lamp between the stop lamp control circuit terminal listed below and ground circuit terminal. Tail/Stop and Turn Signal Lamp - Left and Right - Upper and Lower terminal MJR - with Z75 - E52 Tail Lamp Circuit Board - Left and Right terminal E - with Z75 + E52 and European Tail/Stop Lamp - Left and Right terminal MJR - with X88 Tail/Stop Lamp - Left and Right terminal A - Z88 Tail/Stop Lamp - Left and Right terminal 1 - with HP2
7. Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the selected states. If the test lamp is always ON, test the control circuit for a short to voltage. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance.
8. If all circuits test normal, test or replace the stop lamp.

Center High Mount Stop Lamp Malfunction

1. Ignition OFF, disconnect the harness connector X4 at the BCM.
2. Ignition ON, verify a test lamp illuminates between the B+ circuit terminal 4 and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance or short to ground.
3. Reconnect the harness connector X4 at the BCM.
4. Ignition OFF, disconnect the harness connector at the center high mounted stop lamp.
5. Test for less than 5.0 ohms between the ground circuit terminal B and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
6. Connect a test lamp between the stop lamp control circuit terminal A and ground circuit terminal B.
7. Ignition ON, press and release the brake pedal. The test lamp should turn ON and OFF when changing between the selected states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
8. If all circuits test normal, test or replace the center high mount stop lamp.

1. Perform the «Diagnostic System Check - Vehicle»(ref-364486-S08087544882010063000000) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(ref-364486-S25727745392010063000000) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(ref-364486-S17107648382010063000000) provides an overview of each diagnostic category.

Turn Signal Switch Malfunction

1. Ignition OFF, disconnect the harness connector X1 at the turn signal/multifunction switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal F. If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Left Front and Rear Turn Signal Switch parameter is INACTIVE. If not the specified value, test the signal circuit terminal E for a short to ground. If the circuit tests normal, replace the BCM.
4. Verify the scan tool Right Front and Rear Turn Signal Switch parameter is INACTIVE. If not the specified value, test the signal circuit terminal D for a short to ground. If the circuit tests normal, replace the BCM.
5. Verify the scan tool Hazard Lamp Switch parameter is INACTIVE. If not the specified value, test the signal circuit terminal G for a short to ground. If the circuit tests normal, replace the BCM.
6. Install a 3 A fused jumper wire between the signal circuit terminal E and ground. Verify the scan tool Left Turn Signal Switch parameter is ACTIVE. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
7. Install a 3 A fused jumper wire between the signal circuit terminal D and ground. Verify the scan tool Right Turn Signal Switch parameter is ACTIVE. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
8. Install a 3 A fused jumper wire between the signal circuit terminal G and ground. Verify the scan tool Hazard Lamp Switch parameter is ACTIVE. If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the BCM.
9. If all circuits test normal, test or replace the turn signal/multifunction switch.

Turn Signal Lamp Malfunction

1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Verify that a test lamp illuminates between the LT STOP TRN fuse B+ circuit terminal 1 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
3. Verify that a test lamp illuminates between the RT STOP TRN fuse B+ circuit terminal 3 and ground. If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.
4. Ignition OFF, reconnect the X4 harness connector at the BCM.
5. Disconnect the harness connector at the appropriate turn signal lamp.
6. Test for less than 5.0 ohms between the ground circuit terminal and ground. Park/Turn Signal Lamp - Left front terminal C - with X88/Z88 Park/Turn Signal Lamp - Right front terminal A - with X88/Z88 Turn Signal Lamp - Left and Right front terminal 3- with Z75 Repeater Lamp - Left and Right front terminal 2 - with TR2 Tail/Turn Signal Lamp - Left and Right rear terminal GRD - with X88 Tail/Turn Signal Lamp - Left and Right rear terminal G- w/o X88 Tail/Stop and Turn Signal Lamp - Left and Right Upper rear terminal GRD - with X88/Z75 - EXP - E52 Tail/Stop and Turn Signal Lamp - Left and Right Lower rear terminal GRD - with X88/Z75 - EXP - E52 Tail Lamp Circuit Board - Left and Right rear terminal D - with Z75 + E52 If greater than the specified range, test the ground circuit for an open/high resistance.
7. Connect a test lamp between the appropriate turn signal control circuit terminal and ground. Park/Turn Signal Lamp - Left front terminal A - with X88/Z88 Park/Turn Signal Lamp - Right front terminal D - with X88/Z88 Turn Signal Lamp - Left and Right front terminal 1- with Z75 Repeater Lamp - Left and Right front terminal 1- with TR2 Tail/Turn Signal Lamp - Left and Right rear terminal MJR - with X88 Tail/Turn Signal Lamp - Left and Right rear terminal A - w/o X88 Tail/Stop and Turn Signal Lamp - Left and Right Upper rear terminal MJR - with X88/Z75 - EXP - E52 Tail/Stop and Turn Signal Lamp - Left and Right Lower rear terminal MJR - with X88/Z75 - EXP - E52 Tail Lamp Circuit Board - Left and Right rear terminal B - with Z75 + E52 - with EXP Tail Lamp Circuit Board - Left and Right rear terminal E - with Z75 + E52 - w/o EXP
8. Ignition ON, command the appropriate turn signal ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM. If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
9. If all circuits test normal, test or replace the appropriate turn signal lamp.