My 3.9 Vogue (1991) has a mystery fault. The ABS system pumps all brakes on firmly. After about 30 mins standing the pressure releases ok until the brake is applied again. Good pedal, master cylinder ok. Pipes, calipers etc ok. all checked through.

Any hint would be appreciated before I call The Samaritans!

Best wishes to you all.

Bob

 

Sounds like a failing brake accumlator. When they start to fail, they hold little or no pressure in reserve.
Mike