Inoperative Electric Parking Brake

The electric parking brake (EPB) may be inoperative on some 2018 Acadia, Enclave, Traverse and XT5 models. The Service Park Brake warning lamp also may be illuminated.

To apply the parking brake on Acadia, Enclave and XT5 models, press the EPB button on the left side of the instrument panel. (Fig. 13) To release the parking brake, the ignition must be on. Press the brake pedal first and then press the EPB button.

Fig. 13

To apply the parking brake on Traverse models, pull the EPB switch on the center console. To release the parking brake, with the ignition on, press the brake pedal first and then press the EPB switch.

An inoperative electric parking brake may be due to several different conditions.

 

Water Leak

If the electric parking brake is inoperative and DTC C028F (Left Park Brake Actuator Circuit) or DTC C1586 (Right Park Brake Actuator Circuit) is set in the Electronic Brake Control Module (EBCM), check for water leaking into the rear actuator (Fig. 14), causing a short to ground.

Fig. 14

If DTCs C028F 04 (short to ground) and/or C1586 04 (short to ground) are set, verify which EPB actuator set the DTC and replace the actuator following the appropriate Service Information.

The brake actuator has a newly designed cover. When replacing the actuator, verify that it has the updated cover (Fig. 15, #2), not the old cover design. (Fig. 15, #1)

Fig. 15

 

EBCM Software

If the electric parking brake is inoperative and there has been a previous repair to the brake actuator, the inoperative condition may be caused by a software anomaly in the EBCM.

If there are not any DTCs set and the brake actuators have previously been replaced, program the K17 EBCM with the latest calibration available using Service Programming System (SPS).

 

Weak Battery

If the electric parking brake is inoperative and DTCs C1587 0B (Left Park Brake Actuator – Software Sensitivity or C1588 0B (Right Park Brake Actuator – Software Sensitivity) is set in the EBCM, the vehicle may have a weak battery, which affects the operation of the software. If these DTCs are set, program the K17 EBCM with the latest calibration available using SPS.

 

– Thanks to Tom Burlingame

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