Interior Backlighting Malfunction
Interior Backlighting Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.
Diagnostic Fault Information
Circuit/System Description
With the park lamps ON, the body control module (BCM) receives B+ voltage from the PARK LAMP relay indicating the parks lamps are ON. The instrument panel (I/P) lamp dimmer switch is used to increase and decrease the brightness of the interior backlighting components. With the park lamps ON, the I/P dimmer switch provides a voltage signal that will increase as the brightness of the lights are increased and decrease as the brightness of the lights are decreased. The BCM provides a low reference signal and a B+ voltage reference to the I/P dimmer switch. When the I/P dimmer switch is placed in the desired position, the dimmed voltage setting is applied from the I/P dimmer switch through the I/P dimmer switch signal circuit to the BCM. The BCM interprets the signal and applies the dimmed voltage to the indicator dimming control circuit and the interior backlighting components dim to the requested level.
Reference Information
Schematic Reference
Interior Lights Dimming Schematics (Interior Lights Dimming Diagrams)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Interior Lighting Systems Description and Operation (Interior Lighting Systems Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, command the Parking Lamps ON and OFF with a scan tool. The park lamps should turn ON and OFF when changing between the commanded states.
• If the park lamps do not turn ON and OFF when commanded, refer to Park Lamps Malfunction (Park Lamps Malfunction) .
2. Command the Interior Dimming control ON and OFF with a scan tool. The interior backlighting should change from low to high when changing between the commanded states.
• If the interior backlighting does not illuminate from LOW to HIGH when commanded, refer to Interior Backlighting Malfunction.
3. Observe the interior backlighting while operating the I/P dimmer switch from high to low. The interior backlighting should change from low to high as the switch is operated.
• If the interior backlighting does not change when commanded, refer to I/P Dimmer Switch Malfunction.
Circuit/System Testing
I/P Dimmer Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the I/P dimmer switch.
2. Install a 3A fused jumper wire between the signal circuit terminal C and ground.
3. Ignition ON, park lamps ON, verify the interior backlighting illuminates.
• If the interior backlighting does not illuminate, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
4. Install a 3A fused jumper wire between the signal circuit terminal C and the low reference circuit terminal D. The interior backlighting should illuminate.
• If the interior backlighting does not illuminate, test the low reference 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, replace the I/P dimmer switch.
Interior Backlighting Malfunction
1. Ignition OFF, disconnect the X3 harness connector at the BCM.
2. Connect a test lamp between the control circuit terminal A7 and ground.
3. 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 voltage.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance.
4. Ignition OFF, connect the X3 harness connector at the BCM.
5. Disconnect the harness connector at the component with the inoperative backlighting.
6. Ignition OFF, scan tool OFF, 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.
7. Connect a test lamp between the control circuit and ground.
8. Command the Interior 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.
9. If all circuits test normal, test or replace the component with the inoperative backlighting.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* Rear Side Door Window Switch Replacement (Rear Side Door Window Switch Replacement)
* Radio Replacement (Radio Replacement)
* HVAC Module Assembly Replacement (Service and Repair)
* Fog Lamp Switch Replacement (Service and Repair)
* Hazard Warning Switch Replacement (Service and Repair)
* Instrument Panel Lamp Dimmer Switch Replacement (Service and Repair)
* Transmission Floor Shift Control Indicator Lamp Replacement (Service and Repair)
* Windshield Wiper and Washer Switch Replacement (Windshield Wiper and Washer Switch Replacement)
* Steering Wheel Control Switch Assembly Replacement (Service and Repair)
* Power Mirror Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming