Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Activating/Deactivating The Parking Brake In Stationary Vehicles
Vehicles are defined as stationary up to a speed of 7 km/h.
It is always possible to activate the parking brake. When the driver presses the parking brake switch (3/272) an analog signal is sent to the parking brake module (PBM) (4/115) which activates the electric motor in the brake caliper (6/146-147), which in turn presses on the brake pads.
To deactivate (release) the parking brake the park brake module (PBM) requires information about the following:
- signal from the parking brake switch
- key in ignition, or the engine must be running. Information about this is retrieved from Central electronic module (CEM) (4/56) via CAN-net
- signal from brake pedal position sensor or clutch pedal sensor. Central electronic module (CEM) (4/56) supplies information about the brake pedal's position (applies for key in accessory position) as well as clutch pedal's position (applies to vehicles with manual transmission)
- signal from brake pedal position sensor. Brake control module (BCM) (4/16) supplies information about the brake pedal's position (applies with ignition on, engine running, or at start attempt).
The Park Brake Module (PBM) retrieves information from the above control modules by reading messages on the CAN network.
If all conditions are met the Park Brake Module (PBM) activates the electric motor in the brake caliper and releases the brake pads.
The parking brake can also be activated automatically upon request by Forward Sensing Module (FSM) (Applies to vehicles equipped with Forward Sensing Module (FSM)).
Use the Manual With the Right Hardware
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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