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B2625




DTC B2625

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

DTC Descriptor
DTC B2625 00
- Passenger Compartment Dimming Request Signal Circuit Voltage Below Threshold

Diagnostic Fault Information






Circuit/System Description

The instrument panel (I/P) 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.

Conditions for Running the DTC

* Battery voltage must be between 9-16 V.
* Park lamps ON.

Conditions for Setting the DTC

The BCM detects a short to ground in the LED indicator dimming control circuit.

Actions Taken When the DTC Sets

The BCM will not illuminate the LEDs supplied by the LED indicator dimming control circuit.

Conditions for Clearing the DTC

* The condition responsible for setting the DTC no longer exists.
* A history DTC will clear once 100 consecutive malfunction-free ignition cycles have occurred.

Reference Information
Schematic Reference

Interior Lights Dimming Schematics Interior Lights Dimming Schematics
Connector End View Reference

Component Connector End Views Connector Views
Description and Operation

Interior Lighting Systems Description and Operation Interior Lighting Systems
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Testing

Note: Each back lighted component may need to be disconnect to isolate a short to voltage or short to ground. Use the schematic to identify the following:

* Back lighted components the vehicle is equipped with.
* Component locations on the back lighting dimming control circuit.
* Each components control and ground circuits terminals.

1. Ignition OFF, disconnect the harness connector at any component with inoperative backlighting.
2. Ignition OFF, scan tool disconnected, interior lamps OFF, doors CLOSED, test for less than 5 ohm between the ground circuit and ground.

If greater than the specified value, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit and ground.
4. Command the Incandescent Dimming ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the BCM.

5. If all circuits test normal, test or replace the component with the inoperative backlighting.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Refer to the appropriate replacement procedure for the component causing the condition.
* Control Module References Control Module References for BCM replacement, setup, and programming