Pinpoint Tests

PINPOINT TEST A: AUTOMATIC PARKING BRAKE RELEASE DOES NOT OPERATE
Refer to Vehicle/Diagrams, Electronic Parking Brake for schematic and connector information.

Normal Operation
The parking brake uses an electrically operated solenoid to release the parking brake. With the brake pedal depressed and the gear shift lever moved from the PARK position, the solenoid retracts to release the parking brake. The solenoid is controlled by the release and retract relays which are controlled by the anti-lock brake system (ABS) module. The ABS module provides grounds for the release and reset relays, fused battery voltage is provided to the relays from battery junction box (BJB) fuse 16 (15A) along circuit SBP16 (VT/RD) for actuating the parking brake release solenoid. Fused ignition voltage is provided to the relays from BJB fuse 33 (10A) along circuit CBP33 (WH/BN) for activating the relays. The relays alternately provide power or ground to the park brake solenoid. Actuation of the relays depends on input signals from the brake pedal on/off (BOO) switch and the transmission microprocessor which sends the information along the high speed-communication area network (HS-CAN).

To release the parking brake release solenoid, the ABS module provides a ground path for the release relay along circuit CCB21 (GN/VT). This engages the release relay. The release relay is supplied fused battery voltage from BJB fuse 16 (15A) along circuit SBP16 (VT/RD). When the release relay is engaged, this voltage is supplied to the solenoid along circuit CCB 17 (BU/GN), the solenoid is grounded along circuit CCB 16 (WH/VT), through the reset relay and finally along circuit GD138 (BK/WH).

To reset the parking brake release solenoid, the ABS module provides a ground path for the reset relay along circuit CCB20 (BU/WH). This engages the relay. The reset relay is supplied fused battery voltage from BJB fuse 16 (15A) along circuit SBP16 (VT/RD). When the reset relay is engaged, this voltage is supplied to the solenoid along circuit CCB 16 (WH/VT), the solenoid is grounded along circuit CCB 17 (BU/GN), through the release relay and finally along circuit GD138 (BK/WH).

Possible Causes
^ Fuse(s)
^ Circuit open
^ Circuit shorted
^ Park brake release relay
^ Park brake reset relay
^ Park brake release solenoid
^ ABS module

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