GM Service Manual Online
For 1990-2009 cars only

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 C028B 08: Park Brake Motor Position Sensor Signal Performance-Signal Invalid

DTC C028B 26: Park Brake Motor Position Sensor Signal Low Frequency

DTC C028B 29: Park Brake Motor Position Sensor Signal Too Few Pulses

DTC C028B 2A: Park Brake Motor Position Sensor Signal Too Many Pulses

Circuit/System Description

The electric parking brake control module has an internal motor, apply actuator, release actuator, and temperature sensor. The electric parking brake control module also contains the logic for applying and releasing the parking brake when commanded by the electric parking brake switch. When the electric parking brake control module receives a signal from the switch the internal circuit board temperature is checked to verify it is within operating range before the control module performs the requested operation.

Conditions for Running the DTC

Ignition OFF, ACCESSORY, or RUN mode.

Conditions for Setting the DTC

The electric parking brake control module detects an internal motor position sensor signal malfunction.

Action Taken When the DTC Sets

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

Conditions for Clearing the DTC

    • The electric parking brake control module clears the history DTC when a current DTC is not detected in 40 ignition cycles.
    • Calibrate the electric parking brake control module.

Reference Information

Schematic Reference

Park Brake System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Electronic Parking Brake Control Module 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

Verify DTC C028B is not set.

If DTC is set, perform the Parking Brake Calibration procedure in Module Setup. If the DTC resets replace the electric parking brake control module.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for electric parking brake control module replacement, setup, and programming.