The brake pressure accumulator, a component of the antilock brake system, frequently fails. This may cause a stiff brake pedal, forcing the driver to apply excess pedal pressure to slow down or stop the vehicle.Google+
Car Problem Reports
Jaguar XJ6 Brake Pedal Stiff Due to Failed ABS Accumulator
Jaguar XJ6 Problem
Average Mileage: 112,150 mi (13,100 mi - 175,000 mi)
Visitor, 1990 Jaguar XJ6, 175,000 mi
brake pedal stiff and air lock and break light is on, looks like issue with break accumulator.
To me it sounds like the brake accumulator ball has gone bad on the ABS pump asasembly. The Pump pumps a nitrogen filled ball (diaphragm) with brake fluid. This ball has a valve to let pressure out of the ball and into the brake system to gain power assist brakes. A lot of the times the accumulator ball goes bad and so anytime you press the brake the pump turns on for brakes or the pump runs excessively and burns itself out.
A check for this is to have the car running and listen to the abs pump assembly and see if the pump runs/clicks on and off when there is no brake use. Also have a friend press the brakes while you are watching. Does the pump run every time he presses the brakes?
It could also just be faulty ABS speed sensors, these cars are known for dirty brakes that clog the sensor easily. If the ABS pump seems to be doing fine I would clean up all of the sensors and see where that takes you.
Visitor, 1991 Jaguar XJ6
if i am driving 50 MPH and i the light turns red about an estimated distance of 10-30 yards. i really need to step on the break quite early and slowly increase the force . sometimes it still over shoots and i need to slam on the last few feets.
had front brakes repaired. brake pedal stiff and light on. brought back. changedd the fuse. Brakes worked a little better, but still stiff and difficult to stop. ep car. Brought back. diagnosed as the brake accumulator. Gave estimated repair of $2,000 for parts, labor, tax. Have researched. found new parts for $250-$377. Found qualified labor estimate of $50-100.
Visitor, 1990 Jaguar XJ6, 174,000 mi
its hard to push my breaks down