The body control module (BCM) supplies a voltage reference through the instrument panel (I/P) dimming voltage reference circuit to the interior lamp dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired position, reference voltage is applied through the dimmer switch rheostat and the I/P lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a pulse width modulated (PWM) voltage through the instrument panel lamp control circuits illuminating the components listed below.

The BCM detects a short to ground on the instrument panel lamps control circuit.

The BCM does not attempt to illuminate the instrument panel lamps.

A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Schematic Reference

Interior Lights Dimming Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Interior Lighting Systems Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Ignition ON, command Incandescent Dimming ON with a scan tool. The Incandescent Relay Command parameter should display On and the Incandescent Dimming should illuminate.

1. Ignition OFF, disconnect the X2 harness connector at the BCM.
2. Verify that a test lamp illuminates between the B+ circuit terminal 2 and ground.

⇒	If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the control circuits listed below for a short to ground.

•	Instrument panel lamp control circuit terminal 3 X2

•	Instrument panel lamp control circuit terminal 3 X6

3. Ignition OFF, connect the X2 harness connector to the BCM.
4. Disconnect the harness connectors at all components fed by the BCM control circuits listed below.

•	Instrument panel lamp control circuit terminal 3 X2

•	Instrument panel lamp control circuit terminal 3 X6

5. Ignition ON, clear the DTC with a scan tool.
6. Operate the system within the Conditions for Running the DTC and verify the DTC does not reset.

⇒	If the DTC resets, test the control circuits for a short to ground. If the circuits test normal, replace the BCM.

7. Reconnect each component one at a time and verify that the DTC does not reset.

⇒	If the DTC resets, test or replace the component responsible for setting the DTC.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.