See also:

The concept
HDC is a downhill driving assistant that automatically controls vehicle speed on steep downhill gradients. Without requiring brake application, the vehicle moves at slightly more than twice wa ...

Malfunction
A Check Control message is displayed. On the Control Display, the areas in front of and behind the vehicle are shaded. PDC has failed. Have the system checked. To ensure full operability: ...

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. ...