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DTC B256A

DTC B256A

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 B256A 02

Liftgate Lamp Control Circuit Short to Ground

Diagnostic Fault Information

Circuit Short to Ground Open/High Resistance Short to Voltage Signal Performance
Cargo Lamp Control B256A 02 2 1 -
Cargo Lamp Ground - 2 - -
1. Cargo Lamp Always ON 2. Cargo Lamp Always OFF


Circuit/System Description

When the body control module (BCM) receives a liftgate open signal, the BCM supplies B+ to the cargo lamp control circuit. This will illuminate the cargo lamp.

Conditions for Running the DTC


• Ignition ON.

• The system voltage is between 9-16 V.


Conditions for Setting the DTC

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

Action Taken When the DTC Sets

The cargo lamps are inoperative.

Conditions for Clearing the DTC

A current DTC clears when the diagnostic runs and passes.

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 for scan tool information

Circuit/System Verification

Command the Cargo Lamp ON and OFF with a scan tool. The cargo lamps should turn ON and OFF when changing between the commanded states.

Circuit/System Testing


1. Ignition OFF, disconnect the harness connector at the appropriate cargo lamp.

2. Test for less than 5 Ω between the ground circuit terminal 2 and ground.

3. If greater than the specified range, test the ground circuit for an open/high resistance.

4. Connect a test lamp between the control circuit terminal 1 and ground.

5. Command the Cargo Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

6. 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.

7. If the test lamp is always OFF, test the control circuit for a short to round or open/high resistance. If the circuit tests normal, replace the K9 BCM.

8. If all circuits test normal, replace the cargo lamp.


Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.


• Rear Compartment Courtesy Lamp Replacement - Liftgate

• Rear Compartment Courtesy Lamp Replacement - Quarter Upper Trim

• Control Module References for BCM replacement, programming and setup