34 00 012 Parking brake function check

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IMPORTANT: Follow instructions for Brake testing on test stand.

Drive vehicle onto brake test stand

The parking brake control unit utilizes a plausibility check (wheel speed comparison) to detect the brake test stand within a few seconds and switches to brake test stand mode.

The parking brake indicator light flashes slowly when brake test stand mode is activated and parking brake actuators are released.

Actuate parking brake switch = application of brake pads.

The parking brake indicator light flashes quickly when brake test stand mode is activated and parking brake actuators are partially locked.

Actuate parking brake switch = test force 1

Actuate parking brake switch again = test force 2

Actuate parking brake switch again = test force 3

The parking brake is released again when the button is actuated in the Release direction.

The parking brake indicator light is permanently activated when brake test stand mode is not detected and parking brake actuators are fully locked.

Brake test stand mode is automatically terminated when the vehicle is driven off the brake test stand.

Checking brake force differential at wheel:

Apply parking brake until a wheel circumferential force (measured on brake test stand) of min. 1000 N is reached.

Max. permitted brake force differential right/left ≤35 % (referred to greater brake value).

Fig 1: Checking Parking Brake

Courtesy of BMW OF NORTH AMERICA, INC.