89 XJS, hard brake pedal, wont stop
 

Hello again, it has been so long since my original post that I decided to start a new thread. My 89 XJS had a brake pull to the right last fall, when I tried to use it this spring after being in the garage all winter, it had a very hard pedal and wont stop at all. I tried bleeding the brakes as recommended by members here but cannot get fluid out of the rear calipers and the only brake that I can get any fluid out of is the right front. Pedal only sinks when I open that bleeder, all other calipers the pedal stays hard and no fluid. Pump runs as it should. I am not sure what to do next. Thank in advance.

Hi acauto

When you Bleed the Rear Brakes you need to have the Ignition ON (But don't start the Car)

Also don't let the Brake Pump run for more than 30 Seconds without a 2 Minute Rest in between or you could Burn out the Brake Pump.

Yes, I am aware of that from my earlier post, thanks. I used the exact procedure as described by members here.

Have you bled the low pressure side of the System?

I tried, could only get a weak stream out if the right front caliper and the pedal would go down when doing so. No fluid out of the left front and the pedal remained hard and would not go down no matter how hard I pushed.

Hi acauto

There are quite a number of reasons why your Brakes are not working.

(1) When you turn on the ignition does the ABS light go out

(2) How many Seconds (roughly) does it take to go out

(3) How did you bleed the low pressure side of the System (ie did you bleed the brake pipes on the master cylinder actuator)

It could be that you need a new Accumulator Ball (The Black Pressure Ball) or maybe even a new Brake Pump.

Hard to say at this stage, so best try and eliminate the other options first.

Did you ever manage to get the Brakes working before?

Seeing this happen a lot on the forum. I think this needs to be up there along with Marelli fires. This is disconcerting to say the least when it happens!

Have you replaced all the rubber lines? My 89 had to have that before I could get anything going. Then there is the solenoid valves in the anti lock control block. The accumulator ball, maybe rebuild the calipers.

A quick peek reveals nothing in the sticky thread/FAQ sections covering common ABS problems, fixes, and service procedures. Or am I just not seeing it?

I'd write something up myself but I'm not well versed or experienced on the subject.

Cheers
DD

A little more information,

1. ABS light comes on and pump runs approx 2 second and then the light goes out.

2. Pump runs and lights are on anytime the brake pedal is depressed, only stop when
brake is released

3. Brake calipers and hoses were replaced last fall due to the pulling problem, they
made no difference.

4. Brake were bleed at that time as normal at the bleeders on the calipers. Car was
drivable but with a pull to the right until it sat over the winter, no longer driveable.

5. New problem just discovered, after working the brake pedal, the left front caliper will
be stuck until the bleeder is opened, yet the right front caliper behaves normally?

6. Checked trouble codes, "21" stored. Main valve failure?

When you open the bleeder valve on the front left caliper, does brake fluid 'squirt' out or just a little tiny bit?

Sounds to me like some sticking ABS solenoids. Common on the Teves setup.

Just a tiny bit

Still soundss like a sticky soleniid.

I've got a schematic drawing here somewhere regarding the ABS and how to trouble shoot it. Before someone says remove it, don't give up! It is a good system.

Just a question: how frequent were brake fluid changes?

Hi acauto

I agree with Daim, it does sound like a problem in the ABS Valve Block but even if it isn't, its worth doing anyway.

But before we get in to that are you 100% sure that one or both of your Calipers are not Sticking, as it kinda sounds like at least one of them may be.

And in order to get your Brakes working, it has to be done a step at a time or it will bite you on the backside when you least expect it.

I had a Stuck Caliper and it nearly set fire to the Car.

So if you are in any doubt, you could either put in New Pistons and Seals or else go Service Exchange.

As otherwise anything else you do may not be able to fix it.

The calipers do not stick. They are new as are the hoses but beyond that, the way you know is by the fact that when you open the bleeder and release the hydraulic pressure the rotor turns freely. If the caliper were sticking then opening the bleeder would have no effect. The brake fluid has not been changed entirely, just what was purged during the caliper and hose replacement.

I agree that the problem is in the ABS unit. Just not sure what to do next. I found a service bulletin related to the abs unit but I have not attempted the service. I also mentioned the code "21" that was stored but the description is very general and
I have found no detailed testing procedures. First digit "2" is for a "valve failure" and the second digit "1" is for "Main Valve"

Yeah, I noticed you wrote 21... As said, I'll see if I can find the ABS papers here. I have an e tire book regarding the ABS system and how too's etc.

Ok in that case on the assumption that you have bled the Air out of the Low pressure side of the Master Cylinder Actuator.

The next thing to do is to Check the Valves are working in the ABS Valve Block.

You don't have to pull anything apart (YET!) as the Valves can be Checked externally.

In the ABS Valve Block which is Bolted on the Side of the Master Cylinder Actuator are 6 Valves, all wired up together.

This has got a 7 Pin Plug on the Side.

Which will pull out after you take off the Clip.

One of those Pins is Common and the others go to each valve.

This Pic will show you what the Valve Block looks like inside.

https://cimg6.ibsrv.net/gimg/www.jag...3eee53d85c.jpg

The XJS Valve Block uncovered

The Next thing to do is Test it with your Meter (No need to take the Cover off at this Stage)


Here is how you do the Test (With Thanks to RennsportKC) then come back and we can go from there.


RennsportKCJaguar XJS ATE ABS repair... - RennsportKC

Thanks for that info and link. As it is Sunday afternoon and I have guest waiting for a boat ride I will not have a chance to tackle this until next weekend, as the car is at my lake house in Maine and must head back to Mass. in the morning and wont be back until next Friday.

Please describe "bleeding air out of the Low pressure side of the Master Cylinder Actuator" to make sure I have done that correctly. Thanks