Thread: Brakes won't release on a gradient

I'm guessing you have a D4 - which came with "hill start assist". The parking brakes are applied when you're on a hill at a standstill - like at a set of lights. The moment you press the accelerator, the parking brakes are meant to disengage. I wonder if your D4 has a problem with the brake switch?

Originally Posted by jonesy63

I'm guessing you have a D4 - which came with "hill start assist". The parking brakes are applied when you're on a hill at a standstill - like at a set of lights. The moment you press the accelerator, the parking brakes are meant to disengage. I wonder if your D4 has a problem with the brake switch?

Cheers. Sounds like that could be it. Maybe it's releasing too slowly.

Is the park brake only applied when you change gears on a gradient? Doesn't seem to be a problem when I stop and continue in the same direction on a gradient.

On a dead level surface (my garage) and also out and about at traffic lights (no apparent gradient), each time I release the brake it will hold for a few seconds, then releases - no accelerator applied. This is what is supposed to occur when stopped using brakes on a slope - 'GRC Gradient Release Control', but this should only be active when 'HDC Hill Decent Control' is selected via the HDC select button. Releases straight away when accelerator is applied. I have mentioned it when in at the dealer the last two times, who checked it all over including brake switch adjustment and checking for oil in the booster (s I have read on here somewhere) and they have found nothing. Each time though the pedal is firmer for a while like when new, then it appears to have a little extra slack/sponginess at first application. I don't know what it is, I've just become used to it, but will be mentioning again when in for next service in a few months.