C0291

DTC C0291

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



DTC Descriptor
DTC C0291 02
- Park Brake Release Relay Circuit Short to Ground

DTC C0291 05
- Park Brake Release Relay Circuit Short to Battery or Open




Diagnostic Fault Information






Circuit/System Description

The park brake system uses a pair of solenoids to set or release the park brake pedal. These solenoids are powered by relays which are commanded ON and OFF by the body control module (BCM). When the gear shift lever is taken out of Park or Neutral, the BCM simultaneously activates both solenoids to release the park brake pedal. The release solenoid is deactivated after 2 seconds and The Release solenoid remains activated until the gear shift lever is in Park or Neutral, the engine is OFF, and the park brake switch is closed.


Conditions for Running the DTC

* The ignition is ON.
* The ignition voltage is greater than 8 volts.



Conditions for Setting the DTC

The BCM detects the park brake relay coil 1 control circuit is shorted to ground, voltage, or open.


Action Taken When the DTC Sets

The ABS indicator turns ON.


Conditions for Clearing the DTC

* The condition for setting the DTC is no longer present.
* The body control module (BCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles



Reference Information

Schematic Reference

Park Brake System Schematics ([1][2]Electrical Diagrams)

Connector End View Reference

Component Connector End Views (Connector Views)

Description and Operation

Park Brake System Description and Operation (Description and Operation)


Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)


Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information


Circuit/System Verification

1. Apply the park brake. Verify that the park brake remains applied.
2. Start the engine, and shift the transmission into Drive. Verify that the park brake releases.



Circuit/System Testing

Caution: Chock the wheels to prevent the vehicle from moving. Failure to chock the wheels can cause personal injury when the electrical system is repaired.


1. Remove the park brake release relay from the I/P relay block. Test the relay coil ground circuit terminal C1 for an open. Verify that there is continuity between terminal C1 and ground.

• If the circuit is open, repair the circuit.

2. Ignition ON. Probe terminal C2 with a test lamp that is connected to ground. Command Park Brake Solenoid Relay A ON with a scan tool, in Body, Body Control Module, Special Functions, Miscellaneous Test. Verify that the test lamp illuminates.

• If the test lamp does not illuminate, test the control circuit for an open or a short to ground. If OK, replace the BCM.

3. Command Park Brake Solenoid Relay A OFF with the scan tool. Verify that the test lamp turns OFF.

• If the test lamp remains illuminated, test the control circuit for a short to voltage. If OK, replace the BCM.

4. Replace the park brake release relay.



Repair Instructions

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

* Relay Replacement (Attached to Wire Harness) (Relay Replacement (Attached to Wire Harness))Relay Replacement (Within an Electrical Center) (Relay Replacement (Within an Electrical Center))
* Control Module References (Programming and Relearning)for BCM replacement, setup, and programming