B2625

DTC B2625

Diagnostic Instructions

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

DTC Descriptor

DTC B2625 00
- Display Dimming Pulse Width Modulation (PWM) Output Circuit

Diagnostic Fault Information






Circuit/System Description

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 brightness 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 LED dimming supply circuit illuminating the HVAC control module to the requested level.

Conditions for Running the DTC

* Ignition ON.
* Park Lamps ON.

Conditions for Setting the DTC

The BCM detects a short to ground on the LED dimming supply circuit.

Action Taken When the DTC Sets

The BCM will not attempt to illuminate the LED indicator lamps 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 ignition cycles have occurred.

Circuit/System Verification

Ignition ON, cover the ambient light sensor, vary the interior lamp dimming switch from dim to full bright. The LED lamps should dim and then become full bright.

Circuit/System Testing

1. Ignition OFF, disconnect the harness connectors at all components fed by the LED backlight dimming supply circuit terminal 18 X3.
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 supply circuit for a short to ground. If the circuit test normal, replace the BCM.

4. Reconnect each component one at a time and verify the DTC does not reset as current.

^ If the DTC resets as current, test or replace the component responsible for setting the DTC.

Repair Instructions

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

* Radio Replacement
* Driver Information Display Switch Replacement (Impala)
* Steering Wheel Control Switch Assembly Replacement.