Mending GMC parking brake conditions
This bulletin applies to 2018 GMC Acadia vehicles.
Condition 1: Some customers may comment that the electric parking brake is inoperative. DTCs that may include C028F (left parking brake actuator circuit...C028F 04 06 short to ground) and/or C1586 right park brake actuator circuit C1586 04 06 short to ground).
The cause may be due to water leaking into the rear actuator, creating a short to ground.
If DTCs C028F 04 and/or C1586 04 are set, verify which EPB actuator set the DTC and replaces the actuator.
Condition 2: The electric brake may be inoperative. You may find evidence of a previous actuator repair. The cause may be a software anomaly.
If DTCs are not set and/or the brake actuators have previously been replaced, program the EBCM to the latest available calibration.\
Condition 3: The Service Park Brake lamp may be on. DTCs that may be set in the EBCM include C1587 (left park brake actuator...C1587 0B software sensitivity) and/or C1588 (right park brake actuator...C1588 0B software sensitivity). The cause: software sensitivity caused by a weak battery.
If DTCs are set, program the EBCM to the latest calibration.
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Motor Age StaffMotor Age Staff
Motor Age has been publishing technical content for professional automotive technicians since 1899. Our writers have decades of experience and scores of ASE certifications, and they continue to teach new generations of technicians via classrooms all around the globe, as well as through the books and training manuals they've authored.
