GM Faces Yet Another Safety Investigation

Yes, it’s true. Unfortunately, GM still can’t seem to catch a break.

The electronic parking brake featured on the new 2014 Chevy Impala randomly activates at certain times, often causing a crash.

How does the parking brake work? And how can I fix this myself?

Park brake apply input force is received by activating the Electronic Parking Brake (EPB) switch signaling the EPB control module, and transfers an evenly distributed force through the parking brake cables and equalizer to the parking brake apply levers. The electric parking brake can be used to prevent roll back for vehicles with a manual transmission taking off on a hill; a situation where no roll back is desired.

Tension can be fully released from the park brake cables to allow for service of the park brake system. The tension in the cable can be released with a scan tool or manually. Most GM vehicle with the TRW cable actuated system have the motors located in the passenger-side rear wheel well behind an access panel. On most Ford and Jaguar vehicles, the actuator is in the trunk. It is possible to release the system if the battery is dead. Most of these procedures are outlined in the owners manual that is in the glove box.

Notable Service Procedures

Method 1

1. Turn the ignition switch to the ON/RUN position with the engine OFF.

2. Place the automatic transmission in PARK or manual transmission in NEUTRAL, as equipped.

3. Apply and hold the brake pedal. The brake pedal must remain applied throughout the park brake cable tension release process.

4. Press and hold down the electronic park brake (EPB) switch approximately five seconds.

5. Observe the PARK BRAKE lamp on the instrument cluster.

6. When the PARK BRAKE lamp flashes, release then immediately press and release the EPB switch. The parking brake cable tension is fully released.

7. Release the brake pedal.


Method 2

In the event you need to release the EPB and the battery is dead, the following procedure may be used to release the brakes:

1. Remove the left rear tire and wheel assembly.

2. Remove the left rear wheelhouse panel liner.

3. Remove the protective plug (1) from the EPB manual release.

4. Using an appropriate square-drive tool, rotate the mechanism clockwise until the tension is fully released from the parking brake cables. Up to 50 turns may be required until the parking brake cable tension is fully released.

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