See also:

Deactivating HDC
Press the button again; the LED goes out. HDC is automatically deactivated above approx. 37 mph/60 km/h. ...

Activating HDC
Press the button; the LED above the button lights up. ...

The concept
In addition to the PDC Park Distance Control, the backup camera, can be switched on. PDC supports you when parking. Objects that you are approaching slowly in front of or behind your vehicle ...