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Interior Backlighting Malfunction




Interior Backlighting Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information





Circuit/System Description

The instrument panel (I/P) lamp dimmer switch is used to increase and decrease the brightness of the interior backlighting components. 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 body control module (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 I/P lamps supply voltage circuit and the interior backlighting components dim to the requested level. The BCM also sends a serial data message to the driver and front passenger door modules indicating the dimmed level. The door modules respond by supplying there respective switch backlighting with the appropriate voltage for the desired dimmed setting.

Reference Information
Schematic Reference

* Interior Lights Dimming Schematics (Interior Lights Dimming Schematics)
* Driver Seat Schematics (Driver Seat Schematics)

Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Interior Lighting Systems Description and Operation (Interior Lighting Systems)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

1. Ignition ON, observe the scan tool Dimming Control Signal parameter while operating the dimmer switch from high to low. The reading should change from a high percent to a low percent as the switch is activated.

• If the reading does not change, refer to Dimmer Switch Malfunction.

2. Observe the function of the backlighting components while commanding the LED Dimming or Incandescent Dimming ON and OFF with a scan tool. The backlighting components should turn ON and OFF while changing between the commanded states.

• If the backlighting components do not turn ON and OFF, refer to Interior Backlighting Malfunction.

3. Observe the driver door switch while commanding the Integrated Sw. Backlighting Test ON and OFF with a scan tool. The driver door switch backlighting should turn ON and OFF when changing between the commanded states.

• If the driver door switch backlighting does not turn ON and OFF as commanded, replace the driver door lock and side window switch

4. Observe the passenger door switch while commanding the Integrated Sw. Backlighting Test ON and OFF with a scan tool. The passenger door switch backlighting should turn ON and OFF when changing between the commanded states.

• If the passenger door switch backlighting does not turn ON and OFF as commanded, replace the passenger door lock and side window switch

5. Observe the driver seat memory switch while commanding the Non-Integrated Backlighting Test ON and OFF with a scan tool. The driver seat memory switch backlighting should turn ON and OFF when changing between the commanded states.

• If the driver seat memory switch backlighting does not turn ON and OFF as commanded, refer to Memory Switch Indicator Malfunction.

Circuit/System Testing

Dimmer Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the I/P dimmer switch.
2. Ignition OFF, verify that a test lamp illuminates between B+ and the ground circuit terminal 10.

• 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 9 for a short to voltage. If the circuit tests normal, replace the BCM.

4. Ignition ON, test for B+ between the voltage reference circuit terminal 5 and ground.

• If less than the specified range, test the B+ 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 9 and the B+ reference circuit terminal 5. Verify the scan tool Dimming Control Signal parameter is greater than 2.5 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 I/P dimmer switch.

Interior Backlighting Malfunction

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 ohm 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 inoperative backlighting.

Memory Switch Indicator Malfunction
1. Ignition OFF, disconnect the X4 harness connector at the driver door module.
2. Connect a test lamp between the control circuit terminal 13 and the low reference circuit terminal 4 at the drive door module terminal pins.
3. Command the Non-Integrated Backlighting Test 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 does not turn ON and OFF when commanded, replace the driver door module.

4. If all circuits test normal, replace the memory switch.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Refer to the appropriate replacement procedure for the lighting component that requires replacement.
* Dimmer Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning) for BCM, driver side and passenger side door lock and side window switch replacement, setup, and programming

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