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) dimmer switch is used to increase and decrease the brightness of the interior backlighting components. The I/P dimmer switch provides a voltage signal to the body control module (BCM) 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 a pulse width modulated (PWM) voltage through the light emitting diode (LED) dimming 1 and dimming 2 control circuits illuminating the interior backlighting to the requested level of brightness.
Reference Information
Schematic Reference
Interior Lights Dimming Schematics Interior Lights Dimming Schematics
Connector End View Reference
Component Connector End Views Sunshade - Left (D6I)
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 Control Module References for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool LED Backlight Dimming Command parameter while operating the dimmer switch from high to low. The reading should change from a high percentage to a low percentage 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 Backlight 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 Passenger Air Bag Disable Indicator Backlighting. The phrase PASSENGER AIR BAG should be illuminated.
• If the phrase PASSENGER AIR BAG is not illuminated, refer to Passenger Air Bag Disable Indicator Backlighting Malfunction.
Circuit/System Testing
Dimmer Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the S30 headlamp switch.
2. Ignition ON, test for B+ between the B+ reference circuit terminal 1 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 K9 BCM.
3. Verify the scan tool LED Backlight Dimming Command parameter is greater than 40%.
• If less than the specified range, test the signal circuit terminal 12 for a short to voltage. If the circuit tests normal, replace the K9 BCM.
4. Ignition OFF, install a 3 A fused jumper wire between the B+ reference circuit terminal 1 and the signal circuit terminal 12.
5. Ignition ON, verify the scan tool LED Backlight Dimming Command parameter is less than 30%.
• If greater than the specified range, test the signal circuit terminal 12 for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
6. If all circuits test normal, replace the S30 headlamp switch.
Interior Backlighting Malfunction
Note: Each component with backlighting may need to be disconnected to isolate a short to voltage or short to ground. Use the schematics to identify the following:
* Backlighting components the vehicle is equipped with
* Each component's control and ground circuit terminals
* Component locations on the backlighting control circuit
1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
2. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, and wait 2 minutes. Test for less than 5 ohm between the appropriate ground circuit terminal listed below and ground:
* S75 traction control switch - terminal 4
* S30 headlamp switch - terminal 6
* S13D door lock switch - driver - terminal 1
* P2 transmission shift lever position indicator - terminal B
* S70R steering wheel controls switch - right - terminal 5
* S70L steering wheel controls switch - left - terminal 7
* S72 sunroof switch - terminal 3
* S88 sunroof tilt switch - terminal 3
* S52 outside rearview mirror switch - terminal 5
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the appropriate control circuit terminal listed below and ground:
* S75 traction control switch - terminal 3
* S30 headlamp switch - terminal 7
* S13D door lock switch - driver - terminal 2
* P2 transmission shift lever position indicator - terminal A
* S70R steering wheel controls switch - right - terminal 4
* S70L steering wheel controls switch - left - terminal 6
* S72 sunroof switch - terminal 2
* S88 sunroof tilt switch - terminal 2
* S52 outside rearview mirror switch - terminal 10
4. Command the LED Backlight 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 K9 BCM.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
5. If all circuits test normal, replace the component with inoperative backlighting.
Passenger Air Bag Disable Indicator Backlighting Malfunction
1. Ignition OFF, disconnect the harness connector at P14 passenger air bag disable indicator.
2. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, and wait 2 minutes. Test for less than 5 ohm between the ground circuit terminal 3 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Remove the F54UA fuse from the underhood fuse block.
4. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 1 and ground.
• If the test lamp illuminates, test the control circuit for a short to voltage.
5. Ignition OFF, install the F54UA fuse.
6. Ignition ON, test for B+ between the control circuit terminal 1 and ground.
• If less than the specified value, test the control circuit for a short to ground or an open/high resistance.
7. If all circuits test normal, replace the inflatable restraint instrument panel module indicator.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Automatic or Manual Transmission Control Lever Trim Cover Replacement Service and Repair
* Door Lock Switch Replacement Service and Repair
* Headlamp Switch Replacement Service and Repair
* Inflatable Restraint Instrument Panel Module Indicator Replacement Service and Repair
* Outside Remote Control Rearview Mirror Switch Replacement Service and Repair
* Radio Control Switch Replacement - Steering Wheel Radio Control Switch Replacement - Steering Wheel
* Sunroof Switch Replacement Service and Repair
* Control Module References Control Module References for BCM replacement, setup, and programming