Parking Brake

Parking Brake

COMPONENT LOCATION








INTRODUCTION
The parking brake is an electrically actuated system that operates on the rear brake calipers. Two cables are connected to the rear brake calipers, and act directly on the same pistons used for normal, hydraulic rear brake actuation.

The parking brake is controlled by the parking brake control module. In response to commands from the driver through the parking brake switch, the module controls operation of the parking brake actuator. The actuator adjusts the tension of the brake cables to apply and release the rear brake calipers.

Features of the parking brake include:

^ Manual apply
^ Manual release
^ Automatic apply
^ Automatic release.

For more information on parking brake operation, refer to the Owner's Handbook.

PARKING BRAKE SWITCH





The parking brake switch is mounted in the floor console, rearward of the gear selector. The switch has 3 states:

^ Apply: When the switch is pulled up to apply the parking brake
^ Release: When the switch is pushed down to release the parking brake
^ Neutral: The central default position. The switch returns to this position regardless of parking brake status.

The parking brake switch contains a pair of microswitches for both the apply and release actions. The parking brake control module provides an individual hardwired electrical feed to each of the 4 mircoswitches plus a single ground connection, allowing it to constantly monitor switch status.

PARKING BRAKE CONTROL MODULE





The Parking brake control module is behind the auxiliary junction box and is connected to the vehicles electrical wiring by 2 mulitplugs. The control module is also connected to the high speed Controller Area Network (CAN) bus, allowing it to communicate with other vehicle systems.

The control module monitors the condition of the parking brake switch through a series of hardwired electrical connections and controls operation of the parking brake actuator accordingly.

PARKING BRAKE ACTUATOR





The Parking brake actuator is mounted on the rear cross beam, underneath the vehicle. Operation Of the actuator is controlled by the control module in response to Parking brake switch requests from the driver.

A hall sensor is located within the actuator and provides positional information back to the control module. The principle function of the hall sensor is to ensure the actuator fully releases the parking brake when a static release request is made. The signal provided by the hall sensor is compared to configuration information contained within the control module software to determine when a full release has been carried out.

Further information on the hall sensor can be found in the 'Principles of Operation' section below.

STOPLAMP SWITCH





The stoplamp switch is mounted on the brake pedal bracket. One of the prerequisites for releasing the parking brake is that the foot brake is applied. The parking brake control module is able to determine the position of the footbrake by monitoring the status of the stoplamp switch via a hardwired electrical connection.

The stoplamp switch also forms part of the Anti-lock Brake System (ABS) and the Speed Control system.

INSTRUMENT CLUSTER
Depending on market specification, the instrument cluster may contain a red and an amber brake warning indicator, or only a red brake warning indicator. The functionality of the warning indicators is shown in the table below.





If a parking brake failure warning indicator is active, the message 'CANNOT APPLY PARK BRAKE' or 'PARK BRAKE FAULT' will also appear in the instrument cluster message center. If the vehicle is moving with the parking brake applied, the message 'PARK BRAKE ON' will appear in the message center accompanied by a chime from the instrument cluster.

NOTE: NAS vehicles utilize different instrument cluster symbols and brake warning indicators.

CONTROL DIAGRAM

NOTE: A = Hardwired; D = High speed CAN bus