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TO THE TEVES GURUS:
While in the process of doing individual system checks before starting my rebuilt V12 engine , see my post (1990 xjs: Final check before attempting to start) I noticed that the ABS pump runs constantly with the ignition 'ON". Because I know that the pump should not run all the time, I disconnected the electrical connector to the pump.
Fast Forward, I lifted the rear of the car to prime the oil system and while setting up the jack stands, I observed that the PO or whoever had pried back both rear brake caliper pistons to free up the rotors. The calipers themselves look very crusty so I ordered a pair. That means I have to drop the subframe to do this job which would happen after I get the car running.
In the meantime.........: I have never worked on an XJS with the TEVES system so I do not have a clue as to what to do.
The question I have is whether the prying back of the caliper pistons has anything to do with the ABS pump running constantly or is it something else. After reading up about the TEVES system, I think I understand the procedure for bleeding the rear brakes but if the pump does not stop running, bleeding the rear brake is a moot point.
The first thing I have to address is the issue of the pump running constantly. Because of my 'BARE BONE" understanding of how the TEVES system works, WHERE DO I BEGIN?
As stated in my other posts regarding this car, the PO told me that this was a running car before the engine blew up. However, when I got the car, the seller had started to cannibalize the car and because I had most of the parts removed from the car, I proceeded with the purchase.
Is there anything I should check for to see if anything associated with the ABS system was also removed causing the ABS pump to run constantly?
The brake system issue will be addressed in a few weeks time so I am trying to get all my ducks in a row before attempting a fix. The more I know about the TEVES system the easier my job will be. The main problem would be the issue of the ABS pump running constantly.
Thanks
The pads being depressed will not have anything to do with the pump running.
The way the system works is that when the ignition is switched on, the pump will run until the accumulator is charged. This is indicated by the signal from the Pressure Switch.
Don't let the pump run for more than a minute as it will eventually burn out.
In theory, if the pump constantly runs, it will be because of one of the following reasons:
- a faulty pump which can't generate the necessary pressure and keeps running
- a failed accumulator which is precluding pressure build-up and therefore the pump keeps running
- a faulty pressure switch which is stopping the pump from turning off
- a jammed ABS pump relay (although I'm not sure if that could theoretically cause the problem on its own).
It's quite difficult to pin down which of the above is the problem. The Pressure switch is particularly difficult to diagnose. It's a fairly crude method but you can get some idea of whether the accumulator is building any pressure in the following way:
Ignition off, press the brake pedal repeatedly (up to 25 times). The pedal should get harder and harder as any pressure in the accumulator is discharged.
Foot OFF the brake, turn on the ignition, let pump run for max 60 seconds, turn off ignition.
Press brake pedal once. Does it feel "normal" and not extremely hard as it would have been at the end of the first step?
If the pedal is very hard, it sounds as if no pressure is being built up in the accumulator, so either failed pump or failed accumulator
If the pedal felt normal on that first press, how many presses does it take before it goes extremely hard?
Thanks Paul. Your knowledge of the TEVES system is invaluable. Since the rear brake calipers are going to be replaced, I am going to do that first before getting into the pump issue.
In the meantime I will continue looking at your posts regarding this topic. I do not want to try diagnosing the problem until the calipers are replaced even though I do not think the calipers will move without pressure from the pump. I will post a progress report as I work through the system.
Just to clarify, it's not the pump, per se, that sends any fluid to the rear brakes.
The pump puts pressure into the accumulator, so you now have brake fluid stored under pressure. When you touch the brake pedal, it allows a valve to open in the Actuation Unit. This allows fluid to flow under pressure from the Accumulator to the back part of the Actuation Unit. Thus fluid then moves under pressure to the rear brakes, via the ABS valve block and through a pressure reduction valve.
If the pump can't build up pressure in the Accumulator, then no fluid will flow under pressure to Actuation Unit when the pedal is touched. So no fluid will flow to the rear brakes.
Therefore you will need to ensure you have accumulated pressure before the caliper pistons can be moved outwards and the rear brakes bled.
If you're replacing the rear calipers anyway, that's fine. Just don't push any fluid back from the old calipers when you remove the pads etc. Open the bleed nipples to allow any fluid pressure to escape when you remove the pads.
Thanks for that advice. However, I do not know if the calipers were forced back in the proper way. I believe I will have to find a way to see if the pump is able to pressurize the accumulator. I have to read up some more on how to perform this test. First I have to find and fix the issue of the pump running constantly, then proceed from there.
Thanks for that advice. However, I do not know if the calipers were forced back in the proper way. I believe I will have to find a way to see if the pump is able to pressurize the accumulator. I have to read up some more on how to perform this test. First I have to find and fix the issue of the pump running constantly, then proceed from there.
I might suggest that you don't waste anytime on the pump issue until you've replaced the calibers and properly filled and bled the system. It could be something as simple as too much air in the lines making it difficult to build pressure. Creating a strong baseline of a properly bled system, should make it easier to diagnose if the pump issue continues. Just my 2 cents.
Can I pressure bleed the rear brakes after I replace the calipers? I have a brake pressure bleed setup. I just have to make an adapter to fit the Master Cylinder.
I'm not sure. It MIGHT work. There is a port from the reservoir to the Control Valve that manages the fluid flow to the rear of the Actuation Unit. That port is ostensibly a return port to the reservoir, but it MIGHT allow fluid flow under pressure from the reservoir to the rear of the Actuation Unit and thence to the rear brakes. It COULD work, but I wouldn't guarantee it. I've not read of anyone doing it this way.
Personally, I would sort out the problem of the pump running constantly. Even if you could bleed the rear brakes that way, you will have NO rear brakes IF you do not have pressure in the Accumulator. Pressing the brake pedal will not push any fluid to the rear brakes. The system doesn't work like a conventional system.
As a thought, have you done the ABS blink test, or the ABS diagnostic tests? There are a couple of test conditions which can show if the Pressure Switch is at fault which MIGHT be the cause of the pump running.
Paul, I have to attend to the warning lights on the dash.to see why nothing is lighting up. Like I said earlier, the car was partially cannibalized by the mechanic who had the car before I acquired it so I do not know at this point in time what was removed. I will be working on that during the next few days.
Once I restore the warning light issues , I will proceed.
Sorry to hear you're having probs but if you are doing the Binnacle Lights, then this may come in useful, as while you are about it then you may as well change all the Bulbs for Brighter 5 Watt ones, that could be especially useful, at this time of year when it gets dark
Though first of all you need to remove the Binnacle (same on all Models) pretty much! and the reason I know how to do this is because the GF Showed me what to do and has been banging on about it ever since!
Thanks OB. I also need your expertise based on your experience with the ABS system. Counting on you, Paul and others to help me through this one. I absolutely don't know a thing about the TEVES system except what I have been reading about it. Planning on dropping the rear subframe next week to replace the calipers, flex hose and anything thing else I find when it's on the floor.
To all. I went to Jaguar Heritage website to look for a comprehensive workshop manual for my 1990 XJS. In the "Technical Publications" section I do not see anything listed for the XJS.
Also, If/when i find it, I will need a download since my new laptop does not carry a CD/DVD player. Does anyone know how to find the "Proper Manual" I am working on my ABS system so I need this manual.
Thanks
Unfortunately, there was a commercial dispute some years ago re. the publication and sale of the Workshop Manuals for the various models. And that never seems to have been resolved. Therefore, Jaguar Heritage do not sell the Workshop Manuals at the moment.
There are some publications available and I can maybe find a way of sharing some of that documentation with you.
As regards the Teves ABS system, there are some publications that could help you:
- The description and explanation of the system. Once you've familiarised yourself with that, you will understand a lot more about the unconventional manner of how the brakes operate, in particular the way in which the rear brakes are operated. This highlights why the rear brakes can not be bled in a traditional manner, because the pressure of the brake pedal does not "push" fluid to the rear brakes.
- The Electrical diagram of the ABS system
- The Blink Test Routine, which details the process and the interpretation of the fault codes relating to the ABS system
- The 32 Continuity diagnostic tests, how to perform them and what the results indicate
- The sections in the Workshop Manual that relate to the dismantlement and replacement of components
I have the documentation of all of the above and can share that with you. The Workshop Manual relates to a later model XJS, but fundamentally it's the same for all Teves II ABS systems.
.If you drop me a PM with your email address, I can pull the various docs together and work out how to get them to you. I have the Workshop Manual broken down but the section that contains the Brake section is still 7mb. But we'll find a way of sharing it.
Removing and Refurbing the Cage is nowhere near as difficult as you may think, as I have done 3 of these and never referred to a Manual because for starters, I don't even have one (it really is that easy!)
If you have any time on your Hands, Start by undoing the 4 Bolts (2 each side) that Bolt the Cage to the Car and then replace them with New Bolts just 'Finger Tight' as they will have to be undone and taken out once you are ready to start in earnest but Don't let the IRS Hang Down or it could tear the Rubbers on the Cage Mounts
Also same with the Exhaust, replace all the Bolts with New Ones, 'Finger Tight' But Support the Exhaust or you might 'Crack the Manifold'
Same again with the Propshaft Bolts
New Rear Brake Hose Essential, don't try and undo it just Cut it through with a Bread Knife and then undo the Bolts when you have got the Cage out of the way
Get some New Solid Rotors (Not the OEM Split ones) Also some 1/2in Stainless Steel Tube to make some 'Dummy Shafts' from
Don't bother to Slacken the Hand Brake Cable, just knock up a Hand Brake Cable Wrangler (10 Mins Max to make one!) and will save you HOURS of messing about!
See the Video within that Thread
Also get some New Hand Brake Pads or make your own like I did which again is very easy to do
Also make sure the Car Can't Fall which is why I made a Rig from Scaffolding Poles and you also need a 3 Ton Trolley Jack or preferably 2 of them
Don't try and do it all at once, just break it down into 'Bite Size' Pieces and above all 'Believe You Can do it!'
As for the Rear Calipers I always Gravity Bleed them although you must Bleed the Low Pressure Side of the System before you do anything else
How to Bleed the Low Pressure Side of the Teves Braking System A lot more detail in this earlier Thread that wasn't anywhere near as Scary as I may have made it sound, although it was one of my earlier Threads and I got a bit 'Carried Away' while Writing it! ( No Change there then!)
@ ALEX: Thanks for all the advice. I have dropped IRS cages twice before.( 6 years ago) The first time was a nightmare as I did not know what I was doing. The second time it was a lot easier. This time, with all the input it will be a lot easier but more difficult because I am 7 years older and not as agile as I once was. Definitely, it will be done in bite size pieces.
All of the new parts needed for the rear susp. job was ordered and they have started to arrive. I already have the rear up in the air and I will proceed to support the car across the width of the body from jack point to jack point using a piece of 2x6 planking placing the jack stands under the planking. My 2 hydraulic jacks will support the rear subframe on both sides when I begin to unbolt it. I am in the process of making a jig with pieces of 2x4 to prevent the subframe from tilting forward when it is unbolted. Once it's out, I will use my engine hoist to lift it onto my workbench and do the necessary.
PS: all of this will have to wait until I have the engine running. The crush washers for the oil pipe above the oil filter arrived yesterday, so I will get the oil leak fixed before doing anything else.
see "1990 xjs: Final check before attempting to start" Post #18
As a matter of fact, I have to do this job twice. A while ago, I was attempting to bleed the non-ABS brakes on my running 1988 XJS (H&E version) and I rounded off the bleeder nipple on the left hand side. When I placed the order for the rear calipers I ordered a second set to replace those on the '88 also. I will be working on my back for the foreseeable future. The '88 is in my garage keeping company with my '85 XJ6 which is my daily driver. 1988 XJS 1990 XJS 1985 XJ6
A very nice Collection of Cars that you have there and I also rounded off one of the Bleed Nipples on my V12 which was the main reason why I had to drop the Cage to take it out, at which point I decided to Refurb the IRS
The hardest part for me was undoing the Prop Shaft Bolts, which always seem to need a 'Clonk' with a FBH while making sure the Car can't fall on me, hence the building of the Rig for extra piece of mind
I really enjoyed rebuilding the Cage, it's one of my favorite jobs, unlike removing the Spark Plugs which is one of my worst
Please come back if you get any probs, as someone on here is sure to know the Answer
Thanks Paul. I received the documents. Very much appreciated. It will be a couple of weeks before I start on the ABS system. I am going to drop the rear subframe to replace the brake calipers, bushings and anything else I see requiring my attention before I start on the ABS system. Will post as I get along.
1990 xjs abs issues
