See also:

Automatic deactivation during forward travel
The system switches off when a certain driving distance or speed is exceeded. Switch the system back on if necessary. ...

Malfunction
In the event of a failure or malfunction of the parking brake, secure the vehicle against rolling using a wheel chock, for example, when leaving it. ...

The concept
The system is functional at speeds beginning at approx. 20 mph/30 km/h. It maintains the speed that was set using the control elements on the steering wheel. The system brakes on downhill gradie ...