B255D

DTC B255D

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 B255D 02
- Passenger Compartment Lamp Control 2 Circuit Short to Ground

Diagnostic Fault Information





Circuit/System Description

The body control module (BCM) supplies a voltage reference to the 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 to the BCM. The BCM interprets this voltage signal, then applies a variable voltage through the LED backlight lamp control circuit.

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 (Interior Lights Schematics)
* Interior Lights Dimming Schematics (Interior Lights Dimming Schematics)

Connector End View Reference

Component Connector End Views (Connector End Views By Name)
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 (Programming and Relearning) for scan tool information

Circuit/System Verification

Ignition ON, command the Interior Accent Lighting 2 ON and OFF with a scan tool. The interior accent lighting should turn ON and OFF when changing between the commanded states.

Circuit/System Testing

Note: Each back lighted component may need to be disconnected 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 circuit 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 Interior Accent Lighting 2 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 K9 BCM.
• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 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 (Programming and Relearning) for BCM replacement, programming and setup