Interior Backlighting Inoperative

INTERIOR BACKLIGHTING INOPERATIVE




DIAGNOSTIC FAULT INFORMATION

IMPORTANT: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Testing and Inspection

CIRCUIT/SYSTEM DESCRIPTION
The body control module (BCM) receives an input from the instrument panel (I/P) dimmer switch. The BCM provides the I/P dimmer switch with battery positive voltage and ground. The I/P dimmer switch is a potentiometer that varies the input signal voltage to the BCM. This input determines the intensity level of the backlighting illumination. The driver may change intensity of the backlighting by positioning the I/P dimmer switch between the minimum and maximum settings. The BCM will default to full intensity if the input from the I/P dimmer switch is not within the specified values. The backlighting illumination intensity is controlled by the BCM by varying the pulse width modulation (PWM) voltage that feeds the dimming signal circuits of the individual lamps. All interior backlighting lamps are permanently grounded.

CIRCUIT/SYSTEM TESTING
1. Ignition ON, install a scan tool and command the Interior Lamp Dimming Control ON. All interior backlighting should illuminate.
- If the interior backlighting does not illuminate, repair the I/P lamp supply voltage circuit for an open/high resistance.
- If the I/P lamp supply voltage circuit tests normal, repair the ground circuit of the inoperative backlighting component for an open/high resistance.
2. If all circuits test normal, replace the BCM.

REPAIR INSTRUCTIONS

IMPORTANT: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests

Control Module References for BCM replacement, setup, and programming