The model is a 1990 xjs v12 he. The dashboard abs light has been on since I bought the car but the wheels moved freely when jacked up.

Last week I removed the wheels and when testing the brake system to see if the brakes worked properly, they locked up on me. (brake pedal was hard)
So I ignored it and replaced the the rotors and brakes pads on the front brakes thinking maybe a bleed will fix the issue. Nope.
Now I don't have a manual so I tried bleeding the brakes like any other car. Fluid is reaching the bottom of the front calipers but is refusing to go up
through the bleed valve.

I have tried to diagnose the problem via kirby palmer's instructions but I am now more confused than before.

With the key in the run position I can hear the pump humming and ceasing at 57 seconds. (brake light does not extinguish)
I can also hear the relay click as soon as the pump ceases.

Next when I press in the brake pedal; With the pedal pushed halfway down the pump humming starts and ceases after 4 seconds.

With the key turned off I pressed and released the brake pedal more than 80 times and the pedal did not get hard.

What are your thoughts on all of this? New Accumulator? or something else?

I just realized I have done this testing with two calipers off on both front tires (one on each tire) so I will put those back on and tighten the bleed valves to see if that makes a difference in the testing.

 

The attached tests will tell you exactly what is wrong, no swapping parts and guessing. I had a simple broken ground wire at the distribution block.

 

Whos this guy who almost practically stole my username! >.>

The brake system is definately something you want to Diag properly, throwing darts at it won't help when you lose braking power on a bridge in rush hour, and if you can't I can point you in the direction of a legendary Jag mechanic who will get it done.

 

Hi,

Agree with the previous two posts.

The ALBS system has to be methodically checked through using the tests provided by Time-Pilot to identify any fault you have. It will take time and lots of note taking. I can still remember my wife's face when I explained that she had to rotate the jacked up road wheels at a certain rate whilst I led in the trunk with a multi tester on the ECU to measure the various outputs.

Like you I had a continuously illuminated warning light. Having gone through all the tests I could find no fault - all tests passed. What I did find is that there is a test system that illuminates the warning light when the ignition key is turned to the start position in order to check for bulb failure. I had a short in the wiring that kept this circuit live even after the starter key was released. Possibly you have the same fault if all else checks out.

There is also a fairly crude test system where stored faults can be read from the ABS ECU using a blinking light system (see attachment). This may help you to track any faults down.

It took me several weeks of investigative work to find my fault but then again I am no expert so good luck to you.

Too funny you guys are both in Vancouver - my favourite North American city where I worked for several years.

Cheers,
LeeP

 

Have you driven it? If the brakes feel normal during a normal stop, I would suspect a wheel speed sensor issue. The ABS needs to know the speed of the wheels to work. If the car stops normally when you are not locking a wheel, but the ABS light stays on, often it is because it does not get a proper speed signal. The ABS diagnostic Time-Pilot posted should identify the problem.

 

Hi Vancouverxjsguy

Take some comfort from the fact that you are not alone, as some of us including me have or have had a problem with the Brakes

Though having said that, it sounds like you're doing it wrong

Have a look at this thread by Paul ptjs as this is the only method I know of Bleeding the Brakes that Works

Bleeding the Teves ABS Brake System

 

hahahah....gonna turn into the highlander around here...there can only be one....


A bad sensor will through the light like mentioned. Hell my wifes 2010 Ford edge had the check engine light, traction control light, abs light, and gas cap light all on. Hooked it up to see what the code was. Faulty left rear abs sensor. Took it out and it had a small part of the end cracked. Changed it and all the lights are gone.

So maybe pull them out and check them?

Go to a parking lot in the rain and drive 60kph and hammer on the brakes and test them. You will still have brakes but you will feel the abs working or not.

 

Awesome thanks! Ill go through these test and get back to you with my results. These are a huge help

 

Sorry! My bad your name is too good haha. Who is the mechanic you're referring to?

 

Not with the engine running. The closest ive come to driving it was when my friend towed it up my driveway a year ago. The brakes were working then although they were covered in rust. The ABS diagnostic should figure out what is going on.

 

Alrighty I have gotten some results.

The jag passed all tests except for test 29 and test 31

Notes on test 29 (Inlet and Outlet Valve function): Applied foot brake > to floor > wheels locked
Ignition on > wheels locked
Applied foot brake again > to floor

The ecm was disconnected for a day or to so the brake warning light turned off, but after attempting test 29 the light came back on on.

Notes on test 31 (Pressure warning switch operation): Brake pedal does not become so I could not perform test.

I did not perform tests 11 to 14 for the front and rear sensor voltage because the rear wheels dont move so it is not possible to test atm.

Looks like I need to refurb the actuator. Are there any kits I can buy? Or proper steps that have to be taken?

Thank you all for your help guys.