Auto Hold

The auto hold feature is part of the EPB system and is activated and deactivated through the use of the auto hold switch. For the system to activate, the vehicle must not be moving, the driver safety belt must be buckled and the driver door must be closed. The ABS module receives the driver safety belt buckle status from the RCM, driver door status from the BCM, brake system pressure and the wheel speed sensors allow the ABS module to determine if the vehicle is stopped. Once the previous conditions have been met the auto hold feature can be activated. Once the auto hold feature is activated, the driver presses the brake pedal and the ABS module closes the isolation valves in the HCU to maintain the current brake system pressure at the wheel ends. The ABS module maintains the pressure until the driver presses the accelerator pedal, shifts the transmission into PARK or after a specific time limit has been reached. The ABS module engages the parking brake after 2-10 minutes, depending on the grade of incline the vehicle is currently stopped on, the steeper the grade, the shorter the time.