Hissing Sound until brakes are applied - 1987 Audi 5000 Quattro

[Huw Powell]

Dave Marshall wrote:
> 
> Hi All
> 
> New problem today.
> 
> With the engine running, there is a hissing type of sound coming from near
> the top of the brake pedal.  Step on the brake pedal and the sound goes
> away.

well, the cruise system has disabling switches on the clutch and brake
pedals that are electrical and vacuum - they open the system up to
instantly release the servo.

It would be a pretty wild cruise failure that could do this, but you
might want to check out the possibility.  You're looking for a switch
with a pair of wires and a hose going to it.

I also wonder if it might be some errant non-function of the climate
control, which uses vacuum to operate flaps and such, right?

-- 
Huw Powell

http://www.humanspeakers.com/audi/

http://www.humanthoughts.org/