Essentially, HDCs main function is to modulate the brakes wheel by wheel to allow for maximum traction on a steep grade, where static brake pressure could cause lock up of a wheel, and make it slide.
And yes, the parking brake switch can be used, but it does not apply the parking brake itself until you're at a low speed, it applies the regular brakes at full brake pressure. The manual uses the word 'gradual', which is very much an understatement.
And yes, the parking brake switch can be used, but it does not apply the parking brake itself until you're at a low speed, it applies the regular brakes at full brake pressure. The manual uses the word 'gradual', which is very much an understatement.