The body control module (BCM) supplies a voltage reference through the instrument panel cluster dimming voltage reference circuit to the instrument panel cluster lamps dimmer switch, which is part of the headlamp switch. When the dimmer switch is placed in a desired brightness position, reference voltage is applied through the dimmer switch rheostat and the instrument panel cluster lamps dimmer switch signal circuit to the BCM. The BCM interprets this voltage signal, then applies a variable voltage through the LED backlight lamp control circuit illuminating the components listed below:

The BCM detects a short to ground on the LED backlight lamp control circuit.

The BCM will not dim or illuminate any LED backlighting supplied by the backlight lamp control circuits.

Schematic Reference

Interior Lights 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

Ignition ON, command the LED Dimming test ON with a scan tool. The LED Dimming Relay command should display ON and the LED Dimming should illuminate.

1. Ignition OFF, disconnect the harness connectors at all components fed by the LED backlight dimming control circuit terminal 23 (X1) at the K9 Body Control Module (BCM).
2. Ignition ON, clear the DTC with a scan tool.
3. Operate the vehicle within the conditions for running the DTC and verify the DTC does not reset.

⇒	If the DTC resets, test the LED dimming control circuit for a short circuit to ground. If the circuit test normal, replace the K9 Body Control Module (BCM).

4. Test for less than 5 Ω between the black wire of the appropriate and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance. If the circuit test normal, replace the appropriate accent lamp.

Perform the Diagnostic Repair Verification