It seems to be doing it on and off now, I can make it stop by pumping the brakes several times to the floor, then the pump starts to act normal. Im leaning towards replacing the the pressure switch as I have read it is prone to failure. I dont think its a leaky booster since it does behave correctly ...

Update: I found the valve right ontop of the engine compartment above the pump, I disconnected and cleaned the electrical connector and suddenly it seems to be working properly. I would still appreciate any insight, but at the moment it seems to be working.

I have tried googling this issue, and have found many problems relating to it, however not mine specifically.

The issue is, the pump is running ALL THE TIME. Please see this youtube video to see what im talking about: https://www.youtube.com/watch?v=bndtqskTfqY

My brakes work perfectly, I'm ...

I have been doing a lot of googling and forum browing, and see many topics on this for other model volvos, specifically the D5 volvos.

This is a the 2.9, and no matter what speed, I get a bit of a deep rumble / vibration noise when accelerating and driving. It only happens when I'm in the 1600 ...