Buick Regal: DTC B255D

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 B255D 02

Passenger Compartment Lamp Control 2 Circuit Short to Ground

Diagnostic Fault Information

1. Interior Accent Lighting Malfunction

Circuit/System Description

The body control module (BCM) supplies battery voltage to accent lamps via the accent lamp control circuit. When a door is opened the BCM applies battery voltage to the accent lamp control circuit illuminating the driver and passenger door accent lamps. The accent lamps will remain illuminated until all doors are closed and the ignition is OFF.

Conditions for Running the DTC

Battery voltage must be between 9 - 16 V.

Conditions for Setting the DTC

The BCM detects a short to ground in the accent lamp control circuit terminal 23 X1

Actions Taken When the DTC Sets

The BCM will disable the accent lamp 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 Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEWS - INDEX

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 Testing

1. Ignition OFF, scan tool disconnected, all doors closed, all accessories OFF, disconnect the harness connector the E1W Accent Lamp - Instrument Panel. It may take up to 2 min for all vehicle systems to power down.

2. Test for less than 15 Ω between the ground circuit terminal 1 and ground.

• If 15 Ω or greater

1. Ignition OFF.
2. Test for less than 2 Ω in the ground circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, repair the open/high resistance in the ground connection.

• Go to next step: If less than 15 Ω

3. Connect a test lamp between the control circuit terminal 2 and ground, ignition ON.

4. Verify the test lamp turns ON and OFF when commanding the Accent Lighting ON and OFF with a scan tool.

• If the test lamp is always OFF

1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module.
2. Test for infinite resistance between the control circuit and ground.
   • If less than infinite resistance, repair the short to ground on the circuit.
   • Go to next step: If infinite resistance
3. Test for less than 2 Ω in the control circuit end to end.
   • If 2 Ω or greater, repair the open/high resistance in the circuit.
   • If less than 2 Ω, replace the K9 Body Control Module.

• If the test lamp is always ON

1. Ignition OFF, disconnect the X1 harness connector at the K9 Body Control Module, ignition ON.
2. Test for less than 1 V between the control circuit terminal and ground.
   • If 1 V or greater, repair the short to voltage on the circuit.
   • If less than 1 V, replace the K9 Body Control Module.

• Go to next step: If the test lamp turns ON and OFF

5. Test or replace the E1W Accent Lamp - Instrument Panel.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

Instrument Panel Center Trim Plate Applique Replacement for BCM replacement, programming, and setup.

Control Module References for BCM replacement, programming, and setup.

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