1990 XJ40 Vanden Plas - (should say brake warning light) - driver side rear pad was down to metal, passenger side about half. Replaced both side pads, bled rear brakes per instructions, Treves brake system. Pedal is now mushy, sometimes hard and sometimes goes almost to the floor. When the brake pedal is depressed, brake light always comes on, let go of the pedal, light goes off? ABS and brake light go out within about 10 seconds of starting car. Replaced accumulator with used one, same results.

 

Just a suggestion, but I would try bleeding the whole system again front and back.

You swapped accumulators and probably introduced some air into the system between the master cylinder and the pump, easy to do!

The bleeding procedure is in the archive, if I remember rightly, you bleed the rear with the ignition on and the fronts manually - good luck with it

Larry

 

Hi bgiloni,

You don't mention the brake pad wear sensor - was it worn down to the point that the wire was exposed? If so, the warning lamp may be coming on when the wear sensor wire comes into contact with the rotor, completing the circuit to ground. You can replace the wear sensor or repair it with epoxy to re-insulate the wire.

When you bleed the brake system, first remove as much brake fluid as you can from the master cylinder reservoir and then top up with fresh fluid. Then start bleeding at the corner farthest from the master cylinder (rear right), and bleed until fresh clean fluid comes out. Then move to the next farthest corner from the master cylinder (rear left), then front right, then front left.

Cheers,

Don

 

"If so, the warning lamp may be coming on when the wear sensor wire comes into contact with the rotor, completing the circuit to ground." - Interesting, there was a wear sensor on the rear passenger side pad, it disintegrated, unplugged it and didn't replace it.