For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | 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 | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
LED Dimming Supply | B2625 00 | 2 | 1 | --
1. Interior Backlighting Does Not Dim 2. Interior Backlighting Does Not Dim

### 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 heated seat switches to the requested level.

### Conditions for Running the DTC

The ignition is 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.

### 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.

### Reference Information

#### 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

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Control Module References for scan tool information

### 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 25 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 that 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.

• | Control Module References for BCM replacement, setup, and programming

• | Driver or Passenger Seat Heater Switch Replacement