For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle

• | Review Strategy Based Diagnosis

• | Diagnostic Procedure Instructions

### DTC Descriptor

DTC B255D 02: Passenger Compartment Lamp Control 2 Circuit Short to Ground

### Diagnostic Fault Information

Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance
--- | --- | --- | --- | ---
Interior Backlighting Control | B255D 02 | 2 | 1 | --
1. Accent Lamp LEDs at full intensity and cannot be dimmed or turned Off 2. Accent Lamp LEDs do not Illuminate

### Circuit/System Description

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:

• | Accent lamp - driver door

• | Accent lamp - passenger door

### Conditions for Running the DTC

• | The ignition is ON.

• | The headlamps or park lamps are ON.

### Conditions for Setting the DTC

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

### Action Taken When the DTC Sets

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

### 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 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

### Circuit/System Verification

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.

### Circuit/System Testing

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.

### Repair Instructions

Perform the Diagnostic Repair Verification

• | Front Side Door Sill Courtesy Lamp Replacement

• | Control Module References