Interior Backlighting Malfunction (w/o AN3)
Interior Backlighting Malfunction (w/o AN3)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
Circuit/System Description
When the ignition switch is turned to the RUN position, the radio VF display turns ON at maximum brightness. When the park lamps are ON, all incandescent and LED back lighting turn ON at the dimming level indicated by the instrument panel (I/P) dimmer switch. At the same time all VF displays dim to match the indicated dimming level. The panel dimmer switch potentiometer is an input to the body control module (BCM). When the driver selects a dimming setting by moving the I/P dimming switch potentiometer, all incandescent back lighting lamps are provided with a specific voltage. When the I/P dimmer switch is moved from MIN to MAX, all VF displays, as well as all incandescent back lighting respond from minimum intensity to maximum brightness in response to the I/P dimmer switch
Circuit/System Verification
Ignition ON, observe the scan tool BCM 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 rotated.
If the reading does not change, refer to Dimmer Switch Circuit Test.
If the scan tool dimmer control operates normal, refer to the Interior Backlighting Circuit Test or the LED Dimming Circuit Test.
Circuit/System Testing
Dimmer Switch Circuit Test
1. Ignition OFF, disconnect the harness connector at the headlamp 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 volts.
^ 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 3A 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 volts.
^ 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.
Interior Backlighting Circuit Test
1. Ignition OFF, disconnect the harness connector at the affected component.
2. Ignition OFF, verify that a test lamp illuminates between the listed ground circuit terminal and battery voltage.
* Passenger window switch terminal F
* Headlamp switch terminal 8
* Transfer case control switch terminal 6
* Sunroof switch terminal 5
* Door lock switch terminal B
* Roof beacon switch terminal 1
* Sliding rear window switch terminal D
* Garage door opener switch terminal 3
* Outside rear view mirror switch terminal G
* Driver window switch terminal A X2
^ If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the listed backlighting control circuit terminal and ground.
* Passenger window switch terminal B
* Headlamp switch terminal 7
* Transfer case control switch terminal 5
* Sunroof switch terminal 3
* Door lock switch terminal A
* Roof beacon switch terminal 2
* Sliding rear window switch terminal E
* Garage door opener switch terminal 2
* Outside rear view mirror switch terminal E
* Driver window switch terminal 1 X1
4. Command the dimming test high to low with a scan tool. The test lamp should turn from bright to dim when changing between the commanded states.
^ If the test lamp is always off, test the control circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.
^ If the test lamp is always bright, 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 affected component.
LED Dimming Circuit Test
1. Ignition OFF, disconnect the harness connector at the affected component.
2. Ignition OFF, verify that a test lamp illuminates between the listed ground circuit terminal and battery voltage.
* Right steering wheel switch terminal 1
* Left steering wheel switch terminal 8
* DIC switch terminal 5
* Manual HVAC control module terminal 10 X2
* Multifunction accessory switch terminal 3
^ If the test lamp does not illuminate, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the listed LED dimming control circuit terminal and ground.
* Right steering wheel switch terminal 2
* Left steering wheel switch terminal 6
* Power take off switch terminal 6
* Trailer brake controller switch terminal 7
* IPC terminal 8
* Radio terminal 7 X1
* DIC switch terminal 4
* Manual HVAC control module terminal 1 X2
* Multifunction accessory switch terminal 4
4. Command the dimming test high to low with a scan tool. The test lamp should turn from bright to dim when changing between the commanded states.
^ If the test lamp is always off, test the control circuit for an open/high resistance or short to ground. If the circuit tests normal, replace the BCM.
^ If the test lamp is always bright, 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 affected component.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
* Front Seat Heater Switch Replacement (w/o KB6)
* Steering Wheel Control Switch Assembly Replacement
* Driver Information Display Switch Replacement (without RPO SLT) Driver Information Display Switch Replacement (with RPO SLT)
* Accessory Switch Replacement (with RPO SLT) Accessory Switch Replacement (without RPO SLT)
* Headlamp Switch Replacement (without RPO SLT) Headlamp Switch Replacement (with RPO SLT)