| • | 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. | 
Circuit  | Short to Ground  | Open/High Resistance  | Short to Voltage  | Signal Performance  | 
|---|---|---|---|---|
CHMSL/DM/LAMP Fuse B+  | B2652 00  | B2652 00  | 1  | --  | 
I/P Lamps Control  | B2652 00  | 1  | 1  | --  | 
1. Interior Backlighting Malfunction  | ||||
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. Ground for the I/P dimmer switch is provided at G201.
| • | Battery voltage must be between 9-16 volts. | 
| • | Park lamps ON. | 
DTC B2652 00 will set for the following conditions:
| • | The BCM detects a short to ground in the I/P lamps dimmer switch signal circuit. | 
| • | The BCM detects a short to ground or an open/high resistance in the CHMSL/DM/LAMP fuse B+ circuit. | 
The BCM will not DIM or illuminate any I/P lamps supplied by the I/P lamps dimmer switch signal circuit.
| • | The condition responsible for setting the DTC no longer exists. | 
| • | A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred. | 
Interior Lights Dimming Schematics
Interior Lighting Systems Description and Operation
Control Module References for scan tool information
| ⇒ | If not the specified value, test the B+ circuit for a short to ground or an open/high resistance. | 
| ⇒ | If the DTC resets, test the signal circuit terminal I for a short to ground. If the circuit tests normal, replace the BCM. | 
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |