Hi everyone:

My 1989 XJS 3.6, with ABS brakes, has a strange issue when braking.

When I brake, the car jerks to the left, slamming the steering wheel to this side. We have changed all the bushes & joint *****, and pads, calipers and discs are fine…. but the car keeps turning to the left when hitting the brake.

We have checked and swapped the left and right wheel pipes, and now the car turns to the right when braking. My mechanic is lost and says that he does not know what it could be, he suggests it to the ABS module ... Any ideas?

Thank you

 

Sorry, I was wrong.. I wanted to say ABS actuator system... seems a expensive and hard to find part... So just I want to be sure before doing anything

 

Fergolf,

My initial thought before I read your post fully, was that you had a stuck valve in the ABS valve block (or a broken printed circuit in that valve block). It's a fairly typical symptom of that problem

However, I'm slightly confused when you say you've swapped the "left and right wheel pipes"? Do you mean you've physically swapped over the rigid brake pipes that go from the flexi-pipe connections to the calipers?? Or do you mean you've just swapped over the output pipes at the ABS valve block on the side of the actuator? If it's the latter, that seems to confirm that it's the valve block or its printed circuit, which seems to be causing the release valve on the opposite side to the veering side to stay jammed open thus preventing braking from happening on that side.

The actuation unit itself almost never fails. The issue is nearly always in the abs valve block. It does make the repair "slightly" easier. If it's the printed circuit, you could physically hardwire all the connections as a more robust repair. If it's a jammed valve, you can clean up the valves, clean the filter baskets etc. If everything is then serviceable, your only issue might be finding suitable square-section O-ring replacement seals.

Remember when working on a Teves-ABS equipped car, don't ever push back the pads and pistons on the calipers without first opening the bleed nipple and connecting a pipe to let fluid escape. Otherwise this is how sediment can get pushed back into the valve bock and then cause a valve to get jammed open.

Good luck

Paul

 

Yes, is the latter... yeah, everything points to what you say ... I'm in trouble, I have no idea how to do it, and my mechanic says he doesn't want to open to try to repair it, because he did not dare to a security element. So I'm afraid I can only find another actuator ... hard to find and very expensive ...

 

Fergolf,

It's EXTREMELY unlikely (imo) that it's the main element of the actuation unit. It's much more likely, as I've mentioned that it's the abs valve block which is attached to the side of the actuation unit and was sold originally as a separate part. As you probably know, Jaguar haven't had any complete actuation units or abs valve blocks available for years, so you won't find a new one. Therefore realistically, you've got two options: buy a used valve block or complete actuation unit with valve block, or else get your original fixed.

With the uncertainty that any used unit could also be prone to the sudden failure that you've experienced, I'd be minded to at least try and diagnose and fix your existing unit. They are not at all difficult to take apart. You can even test the integrity of the printed circuit to some degree whilst it's in situ by firing each valve to see if it operates through the plug connection.

There are quite a few threads on here discussing the abs valve block and you'll see how to test the valves operating and also pics of how to take the block apart etc. Maybe have a search through the threads and you'll quickly find lots of info.

Good luck

Paul

 

Hi Fergolf

Panic Not!

As this is a very easy and inexpensive repair, which I have done on all but one of my XJS's

So I will give you the shortened version first and then follow this up with my Thread with all the Photos and details that you need to do the job

Inside the ABS Valve Block on the side of the Master Cylinder Actuator are Six Valves, which are all joined together with Ribbon Connectors that have gone Fragile and Crispy, due to years of being exposed to Vibration and Heat, where the chances are that one of these Ribbons has Broken

Which would cause the Car to '******' to one side of the road as you have described

So how would you know?

In order for you to find this out you need to Test to see if these Valves are all 'Clicking' where the way you do this, is also described in a Video inside my Thread, very easy and simple to do even if you know nothing about Auto Electrics

Where although you can do this while the Master Cylinder Actuator is still inside the Car, it is a little bit easier if you take the Master Cylinder Actuator out of the Car in one piece with the Valve Block still attached to the side, which you will probably end up doing anyway

Having unplugged the Electrical Plugs, there are only 4 Bolts holding it in where removing it in one piece should not take you more than an hour and then do the Test on the Valves as described in my Video, where you will almost certainly find that one of those Valves isn't 'Clicking'

Where should that then be the case it's 99% Certain that one of those Ribbon Connectors has broken inside the Valve Block, at which point you can take the lid off the Valve Block and then have a look for yourself but keep the Valve Block facing upwards, or all the Valves can fall out and in doing so break All the Ribbons

In any event at this Stage draw yourself a diagram as well as taking some photos of how the Valves are all wired together, as otherwise its easy to get lost

At which point you have a Choice which is either to rewire the Valve Block using Heatproof Silicon Wire or buy a New Valve Block which are supposed to be NLA except there's an answer to that

Although before we get to that, take the Valve Block to a Professional Soldering Shop (Radio Shack) to Re-wire the Valve Block for you, as if you attempt to do this yourself and get a dry joint or otherwise get in a mess, then this could very easily cause an Accident and maybe even spin your Car off the Road

Or else buy yourself a New Valve Block to Bolt on the Side of the Master Cylinder Actuator in place of the Old one

But wait these Valve Blocks are NLA so what do you do now?

'Not a lot of People know this' as 'Michael Cain' would say but an XJ40 Valve Block is Virtually the same, all apart from the Back Plate which although a little bit different will bolt straight on without any problems, although you can swap the backing plate with the Old one if you really want to go to the trouble (which I did not)

Round figures about Ł250 which is a bit of a Bargain, when you consider a New Master Cylinder Actuator (also NLA) was around Ł1,500

Fixing or Replacing the Valve Block on the 'Master Cylinder Actuator' which was causing the XJS to violently pull to one side of the road

 

Thanks a million, God bless you ... A shame you're not my neighbor!

Everything seems clear in your valuable messages. The big problem is finding someone qualified to do that job on my car. I have neither the knowledge, nor the site, nor the tools to do it ... and finding someone who dares to do it is going to be very difficult, since some mechanic I have contacted does not want to touch it as it is a security element and they don't want to be held responsible for the result... I'll continue trying ... or will I have to buy a used and expensive part.

I have also read that braking hard on slippery surfaces, making the ABS work, could be solved… but I am skeptical, although I will try it….

 

One doubt ... if what I need is only the valve block, this was offered separately with the ref JLM11337, valid for both RHD and LHD.

If buy the entire actuator kit, then part number for my car, that is LHD (JLM1475), and RHD (JLM1476) are different ... but I suppose that if valve block is the same, so I could use a JLM1476 part for RHD cars, and only take advantage of his valve block, am i right?

 

Fergolf,

You wont find a new actuator LHD or RHD imo. Jaguar haven't had any, certainly for the last 17 years!

Fitting a new valve block isn't difficult for a good mechanic. The most difficult things are finding new O-ring seals (You might have to use your existing ones), bleeding the low pressure side of the braking system (easy) and then bleeding the wheel circuits properly (you MUST do this unusual procedure the correct way).

I appreciate the difficulties you may have in either fitting the valve block yourself or finding someone to recondition your existing one. Maybe try contacting the Spanish Region representative of the Jaguar Enthusiasts Club www.jec.org.uk and see if they can point you in the right direction

Good luck

Paul

 

Hi Fergolf

The 'Italian Tune up' idea, won't really work in this instance and could do more harm than good, as you will almost certainly find a broken wire inside the Valve Block

So just take the lid off the Valve Block and 99% you are going to find a broken ribbon wire on one of the Valves, so what I suggest is you take the whole thing with the Valve Block Still attached to the Master Cylinder Actuator (with the lid screwed on just finger tight) to your local 'Radio Shack' type Soldering Shop

And then take the Lid off the Valve Block, so that they are able to see the Broken Ribbon Wire for themselves and then ask them to Rewire All the Valves with Heatproof Silicone Wire, taking your hand drawn diagram and a photo with you, so that they can see how it goes

It is absolutely imperative that you have a Professional do the Soldering work for you, so know matter how good you think your are or one of your friends think they are, this happens to be just one of those job that should be left to the Experts who know what they're doing and really shouldn't cost more than a few dollars

The hardest part of the process could be Bleeding The Brakes! (everyone's favourite job!) NOT!

Good Luck

Alex

 

Yes, but in the case that I bought a used one, it is very possible that RHD part JLM1476 is cheaper or even easy to find in the UK than the another one.

 

Fergolf,

It may be easier to find a used complete actuator unit than just a valve block, but it's one of the occasions where I'm not sure I would buy a used part rather than a new one, or else get the original fixed.

The valve block problem is a very recent issue issue on XJSs. I'd never seen one fail until about 5 years ago. There are two forms of failure. One is the electrical ribbon circuit that controls the valves. the other is microscopic particles of debris / rust also causing a release valve to stay open. This is exacerbated if you just push the caliper pistons back when fitting new pads. Also rust buildup on the valves from water contamination in the brake fluid if not changed very frequently. The problem with a used unit is that you just don't know if its any better than yours, and of course, it has come off an end of life car.

I would only buy a used actuation unit or separate valve block if I was then going to strip the valve block apart and recondition it. That's just my personal view.

Do let us know what you decide.

Good luck

Paul

 

Hi Fergolf

Just because a Mechanic either doesn't want to do it, or has never done it or doesn't know how to do it, does not in anyway mean that you can't do it as regardless of which way you go the Master Cylinder Actuator with the Valve Block still attached, will almost certainly have to come out of the Car

(1) Its going to make a bit of a mess so don't let any Brake Fluid drip onto the Paintwork or it will Strip the Paintwork in an instant, so siphon out the Brake Fluid from Reservoir using a 'Turkey Baster' or something like that, then Cover the Wings/Fender with some old Towels just in Case and have some soapy water standing by

(2) Don't get psyched out by convincing yourself that this is a difficult job because its not and I'm telling you this from experience of having to do this job on my own Cars

(3) Having Siphoned out the Brake Fluid and then protecting the Paintwork against any possible Spills disconnect the Electrical Plugs from the Master Cylinder Actuator and then undo the Brake Pipes that go into the side of this (again watching out for any Brake Fluid Spills) especially when you remove the Braided Hose

(4) No need to remove the Reservoir or even the Air Filter Boxes, as the Master Cylinder Actuator is only held in by 4 Bolts, so undo those and then remove the Master Cylinder Actuator with the Valve Block and the Reservoir attached all in one go (just be careful not to break the 'uber expensive' Brake Switch down in the Foot well)

(5) That wasn't too difficult was it? The hardest part is beating those 'Can't do it demons in your head'

(6) Once the Master Cylinder Actuator is out of the Car, turn the whole thing on its side, so the Lid of the Valve Block is pointing uppermost towards the Sky or when you take the Lid off all the Valves will fall out 'ask me how I know or rather don't!'

(7) Only take the Lid off and NOT the Valve Block itself (because you don't need to) or at least you don't want to at this Stage and may in fact never need to remove it, as some things are better left undisturbed

(8) Having Carefully Removed the Lid have a look for a Broken Wire but don't disturb those Ribbons any more than you have to, as your Soldering Expert may well want to use those as a Guide when replacing all of them with Heatproof Silicone Wire

(9) At this point as I've mentioned before, do a quick and dirty drawing of what wire goes where and also take some Photos as a back up, then without disturbing anything put the Lid back but this time only finger tight, as it will have to come off again when your Soldering Expert replaces All those Ribbons with Heatproof Silicone Wire

(10) As tempting as it may well be Don't cut any corners by just Soldering back that Broken Wire as you want ALL those Valves Rewired and not just one of them or you'll be storing up a problem that may bite you on the backside when you least expect it

(11) Take the Master Cylinder Actuator with the Reservoir and the Valve Block still attached to your Soldering Expert and then explain what you would like them to do by showing them the drawing and the Photos and only take the Lid off the Block to Show them what's inside, when they hopefully tell you that they will be happy to do it

(12) That is really all that there is to it, apart from getting them to Check that the Valves are 'Clicking' when 12 volts are applied (as in the Video)

Then all you have to do is put it back and Bleed the Brakes! where Bleeding the Brakes could well turn out the hardest part of the Job, so when it gets to that stage
Paul (ptjs) will show you how do this with one of the only ways that works

Good Luck

Alex

 

I would be checking the solenoids in the abs actuator for corrosion and the offending wheel abs sensor. cheers

 

I update the issue ... although we were clear about the cause of the problem, my mechanic changed the brake fluid, bleed brakes on the right way, and also the hose of that wheel, and although the problem logically persists, it has improved a lot, the pull to the left is much smoother, and It is only noticeable when braking really hard, at considerable speed. Anyway, to fully solve the problem, I was almost determined to buy a complete used actuator ... Some already repaired are sold at a very high price, but I have seen used of various prices, and some with very little mileage and that was they may not fail.

My idea was to install a used one in the car and cross my fingers, and once my actuator was out of the car, proceed to attempt its repair by following the valuable help messages in this thread. But before that I thought of contacting what is possibly the best Jaguar specialist here in Spain, the Mendieta Sport Cars workshop, in the city of Barcelona (180 miles from my home), and they told me that without a problem, that they knew about the problem and have already repaired several for a much lower price than ask for a used actuator. Made by professionals and with guarantee. So this is the solution I'm going for, next month I'll take my car for a general overhaul, adjust tappets and more, and also solve this ABS problem too. I'll tell you about the final result.

 

They are already working on my car. One question: I've been asked if the ABS warning light ever came on. In my case, it has never been turned on despite this problem.

To any of you, when you have had this problem with the ABS actuator, did the ABS warning light on the dashboard ever come on?

 

Hi Fergolf

If you get a problem with the Teves Master Cylinder Actuator, the ABS Light almost always will come on where it is nearly always a case of wanting the ABS Light to go off and so the fact that the ABS light does not come on in your Car, could be something as simple as a dud bulb

Especially if the ABS Light does not come on when you turn on the ignition

 

Yes, when turn the ignition the ABS light works.... but when braking, and the car pulls to left, the ABS light never goes on.

 

Hi Fergolf

In that case it sounds like the original diagnosis of a broken Ribbon Connector inside the Valve Block of the Master Cylinder Actuator, as that is very often why the Car will ****** to the left

This is a very easy fix for an electrical Shop to do, if you can show them what is wrong and ask them to rewire it (replacing the ribbons with high temp Silicon Wire) although in your case it may be best to send your Complete Master Cylinder Actuator off to a firm for a Professional Rebuild

Though while not the Cheapest option may be the best one to choose, as you do need to know what you're doing when its something as important as the Brakes

 

Fergolf,

As mentioned, I do not believe that the problem lies in the actuator. If the calipers and pads are operating smoothly, It sounds like it's in the abs valve block.

I wouldn't fit a used actuator + valve block assembly. You'll just have another problem waiting to happen with a 30-year old valve block. Just strip and fix your existing valve block.

Good luck

Paul