Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach. |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category. |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Instrument Panel Lamps Supply Voltage | B2625 02 | 2 | 1 | -- |
Instrument Panel Lamps Dimmer Switch Signal | 1 | 1 | -- | -- |
Park Lamp Supply Voltage | 4 | 4 | 3 | -- |
Instrument Panel Lamps Dimmer Switch Low Reference | -- | 1 | 1 | -- |
1. Interior Backlighting Does Not Dim 2. Interior Backlighting Inoperative 3. Park Lamps Always On 4. Park Lamps Inoperative | ||||
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.
Reference Information
Schematic Reference
Interior Lights Dimming Schematics
Connector End View Reference
Lighting Systems Connector End Views
Electrical Information Reference
Scan Tool Reference
Circuit/System Testing
- Ignition ON, install a scan tool and command the Interior Lamp Dimming Control ON. All interior backlighting should illuminate.
- If all circuits test normal, replace the BCM.
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for BCM replacement, setup, and programming
