See also:

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

Reference
This chapter contains technical data, short commands for the voice activation system, and an index that will quickly take you to the information you need. ...

Activating HDC
Activating HDC Press the button; the LED above the button lights up. The LED flashes when the brakes are applied automatically. ...