Buick Regal: DTC C1587

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 provide an overview of each diagnostic category.

DTC Descriptors

DTC C1587

Left Park Brake Actuator

For symptom byte information, refer to: Symptom Byte List

Circuit/System Description

The Electronic Brake Control Module will diagnose the park brake motor circuits to verify that they are functioning properly. The park brake motor circuits are used to command actuator motor operation, which will apply and release the parking brake. These circuits are used to activate the actuator, which applies or releases pressure on the rear caliper pistons, ultimately applying and releasing the park brake.

When the Park Brake Switch is pulled, a signal is sent to the Electronic Brake Control Module which will supply 12 V to the apply control circuits and ground to the release control circuits which will cause the left and right park brake actuators to activate causing the park brakes to engage. When the Park Brake Switch is pressed, a signal is sent to the Electronic Brake Control Module which will supply 12 V to the released control circuits and ground to the apply control circuits which will cause the left and right park brake actuators to activate causing the park brakes to release.

Conditions for Running the DTC

• Ignition OFF, ACCESSORY, or RUN mode.
• Battery voltage is between 9 - 16 V

Conditions for Setting the DTC

The Electronic Brake Control Module detects a malfunction in the left park brake actuator.

Action Taken When the DTC Sets

• The parking brake is disabled, one release allowed.
• A message and/or a warning indicator may be displayed.

Conditions for Clearing the DTC

• The Electronic Brake Control Module will clear the DTC after 40 consecutive ignition on/off cycles with at least one test pass in each ignition cycle and no test fail result.
• The condition for the DTC is no longer present.

Reference Information

Schematic Reference

Park Brake System Wiring Schematics

Connector End View Reference

COMPONENT CONNECTOR END VIEW INDEX

Description and Operation

Electronic Parking Brake Description

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

1. Ignition ON.

2. Verify that DTC C1587 is not set.

• If the DTC is set

1. Perform the Park Brake Calibration learn procedure. Refer to Park Brake Calibration.
2. Ignition ON.
3. Apply and release the park brake.
4. Verify the DTC is not set.
   • If the DTC is set, replace the M104L Park Brake Actuator - Left.
   • Go to next step: If the DTC is not set
5. All OK.

• Go to next step: If the DTC is not set

3. All OK.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.

• Parking Brake Actuator Replacement (GNC)Parking Brake Actuator Replacement (GNQ)
• Control Module References for control module replacement, programming and setup

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