B0655

DTC B0655

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 B0655 5A
- Brake Lamp Switch Circuit Not Plausible

Diagnostic Fault Information





Circuit/System Description

The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal to the body control module (BCM). The BCM will apply battery voltage to the right, left and center stop lamp control circuits and to the trailer brake control module if equipped.

Conditions for Running the DTC

When the brake pedal is applied.

Conditions for Setting the DTC

The trailer brake control module receives a serial data message from the BCM that the brakes have been applied, but the trailer brake control module does not detect a signal voltage on the center high mounted stop lamp control circuit.

Action Taken When the DTC Sets

The brake lights on the trailer will be inoperative

Conditions for Clearing the DTC

* The DTC will be current for as long as the fault is present.
* When the fault is no longer present, the DTC will be a history DTC.
* A history DTC will clear after 50 ignition cycles.

Reference Information
Schematic Reference

Trailer Connector/Provision Schematics (Trailer Connector/Provision Schematics)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

Exterior Lighting Systems Description and Operation (Exterior 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

Observe the function of the E6 center high mounted stop lamp while pressing and releasing the brake pedal. The E6 center high mounted stop lamp should turn ON when the pedal is pressed and OFF when the pedal is released.

If the E6 center high mounted stop lamp is always ON or always OFF, refer to Stop Lamps Malfunction (Stop Lamps Malfunction)
If the E6 center high mounted stop lamp turns ON and OFF as commanded, perform the Circuit/System Testing.

Circuit/System Testing

1. Ignition OFF, disconnect the X1 harness connector at the K67 trailer brake control module.
2. Connect a test lamp between the signal circuit terminal 14 and ground.
3. Ignition ON, command the Center Brake Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF while changing between the commanded states.

• If the test lamp is always ON, test the signal circuit for a short to voltage.
• If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance.

4. If all circuits test normal, replace the K67 trailer brake control module.

Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

Control Module References (Programming and Relearning)for trailer brake control module replacement, programming and setup