When the headlamp switch is placed in either the HEAD or PARK position, ground is applied to the park lamp signal circuit to the body control module (BCM). The BCM responds by applying ground to the park lamp relay control circuit. This energizes the park lamp relay coil causing the relay switch contacts to close allowing battery voltage to flow to all of the park, tail, license, marker lamps, interior ambient lighting, and to the BCM. The BCM receives the voltage from the park lamp relay indicating the park lamps are ON. The BCM uses this signal to command the interior backlighting ON and OFF. 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 B+ voltage signal and a low 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 indicator dimming control circuit and the interior backlighting components dim to the requested level.

DTC B2625 02 will set when the BCM detects a short to ground in the indicator dimming control circuit.

When DTC B2625 02 is present, the BCM will not illuminate the interior backlighting supplied by the indicator dimming control circuit.

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

1. Ignition OFF, disconnect the harness connectors at the following components:

•	Adjustable pedal position switch - with JF4

•	Automatic transmission control indicator

•	Door lock switch - driver

•	Door lock switch - front passenger

•	Fog lamp switch - with T96

•	Hazard Switch

•	Heated seat switch - driver with KA1

•	Heated seat switch - passenger with KA1

•	HVAC control module

•	I/P dimmer switch

•	Outside rearview mirror switch

•	Rear compartment lid release switch

•	Steering wheel controls - left with 4 spoke steering wheel

•	Steering wheel controls - right with 4 spoke steering wheel

•	SWC DIMMING fuse - with 3 spoke steering wheel

•	Traction control switch - with NW7/NW9

•	Window switch - driver

•	Window switch - front passenger

2. Ignition ON, with a scan tool clear the DTC and operate the vehicle within the conditions for running the DTC and verify the DTC does not reset.

⇒	If DTC B2625 02 sets as current, test the indicator dimming control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.

3. Reconnect each component one at a time and verify that the DTC does not reset as current after each component is reconnected.

⇒	If the DTC sets as current, test or replace the component responsible for setting the DTC.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.