Buick Regal: Description and Operation

ELECTRONIC PARKING BRAKE DESCRIPTION

Vehicles with the electric parking brake have a switch in the center console or on the dash, which takes the place of the manual parking brake system, the foot pedal and release handle. In case of insufficient electrical power, the electric parking brake cannot be applied or released.

Electronic Brake Control Module

The parking brake function is integrated into the Electronic Brake Control Module. The Electronic Brake Control Module contains the logic for applying and releasing the parking brake when commanded by the Park Brake Switch.

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.

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.

The Park Brake Motor Position Sensor is an internal sensor to the park brake actuator, this sensor is used to monitor the park brake motor position.

Electric Parking Brake Apply

The electric parking brake can be applied any time the vehicle is stopped or in motion. The electric parking brake is applied by momentarily lifting up on the park brake control switch. The red park brake light will momentarily flash while the parking brake is being applied. Once fully applied, the red park brake light will turn on. If the electric parking brake is applied while the vehicle is in motion, a chime will sound, and the message "Release Park Brake Switch" will be displayed.

If the red park brake light is flashing, the electric parking brake is only partially applied or released, or there is a problem with the electric parking brake. The message "Service Park Brake" will be displayed.

The vehicle may automatically apply the electric parking brake in some situations when the vehicle is not moving. This is normal, and is done to periodically check the correct operation of the electric parking brake system.

Electric Parking Brake Release

To release the electric parking brake, turn the ignition switch to the ON or RUN position, apply and hold the brake pedal, and push down momentarily on the park brake control switch. When the electric parking brake is released the red park brake light turns off.

The electric parking brake can be used to prevent roll back for vehicles with a manual transmission taking off on a hill. In a situation where no roll back is desired, an applied electric parking brake will allow both feet to be used for the clutch and accelerator pedals in preparation for starting the vehicle moving in the intended direction. In this situation, perform the normal clutch and accelerator actions required to begin moving the vehicle. There is no need to push the switch to release the electric parking brake. To disable this feature lift and hold the park brake control switch while the vehicle is in motion, this will keep the electric parking brake applied.

PARK BRAKE SYSTEM DESCRIPTION AND OPERATION

Electronic Park Brake System

By pulling the park brake switch, the actuators on each rear disc brake caliper will clamp the rear brake pads to the rear disc brakes to apply the electronic park brake. The red park brake lamp shows the status of the activated electronic park brake and is illuminating during the ON position of the ignition switch.

By pressing the park brake switch, the actuators on each rear disc brake caliper will unclamp the rear brake pads from the rear disc brakes to release the electronic park brake. The red park brake lamp will extinguish.

Non mechanical problems with the electronic park brake system can be localized with a diagnostic scan tool. Before a repair service procedure on the rear brakes is carried out, the electronic park brake system must to be set in service mode.

This can be done with the 2 following methods:

Manual Method

1. Change the transmission gear to neutral or park position.

2. Press and hold the push button start switch for 10 seconds, with the brake pedal not applied. This will place the vehicle in Service Mode (Ignition ON with the engine OFF).

3. Press brake pedal several times until brake booster vacuum is empty.

4. Press the brake pedal and press the park brake switch until the orange park brake lamp begins to flash. By keeping the brake pedal applied, release and re-press the park brake switch for approximately 5 seconds.

5. Release the brake pedal. The orange park brake lamp extinguishes for a moment after which the rear brake calipers are retracting.

Scan Tool Method (only use if manual method fails)

1. Install the scan tool to the vehicle and perform the rear brake caliper piston retract.

It is not allowed to rotate back the rear brake caliper piston of a brake caliper. The rear brake caliper piston can be pushed back with a normal brake caliper piston spreader tool.

After the repair service of the rear brakes, the electronic park brake system needs to be reset from service mode before the vehicle can leave the workshop.

This can be done with the 2 following methods:

Manual Method

1. Change the transmission gear to neutral or park position.

2. Press and hold the push button start switch for 10 seconds, with the brake pedal not applied. This will place the vehicle in Service Mode (Ignition ON with the engine OFF).

3. Press the brake pedal and pull the park brake switch until the orange park brake lamp extinguishes and the rear brake calipers are extending.

4. Release the brake pedal.

Scan Tool Method (only use if manual method fails)

1. Install the scan tool to the vehicle and perform the rear brake caliper piston extend.

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