Hi-I am a new owner of a 1989 XJS V12. I am having brake issues. I have replaced the accumulator and they improved a little, still have the ABS light that comes on occasionally on the dash. Was suggested that the ABS Actuator might need to be replaced. Can only find a couple and they seem rather pricey. Does anyone know of anyone that right rebuild/refurbish the part?

Appreciate any help.
Thanks

 

Welcome to the Forums.

Please do an Intro in the New Members Area when time permits.

have a search in this section for Orangeblossom. He has done a lot of work on his ABS, and has a very detailed thread on what he did.

Pricey, YEP, that is a fact.

 

What are the issues you are having?

The actuator (master cylinder) doesn't fail as much as the valves (ribbon cable falling off) as well as the high pressure pump failing.

I built a DIY ribbon cable and valve tester to see if it all works when I fancy doing so. I would recommend or at least putting power to the individual terminals of the plug to troubleshoot and nail down on the main issue.

As you wrote, that a new accumulator helped, I would be assuming, not knowing what symptomes you have, that you are having pressure problems. The light can be indicating too lower pressure...

 

Hi Jseaman

The Actuator hardly ever goes wrong and if you had a problem with the Valve Block on the side of this, the chances are that your Car would very violently ****** to one side or the other. as opposed to just pull

So the first thing to do to try and correct the problem you are having is to Bleed the Brakes, which need to be done in a very specific way and where the only method I know of that works was that devised by Paul (ptjs)

Have a look at this Post by rwolac in which Paul describes this method of Bleeding the Teves System in more detail

Bleeding The Teves Mk1V Master Cylinder Actuator Braking System

But before you Bleed the Brakes, you need to Bleed the 'Low Pressure Side Of The System' or when it comes to Bleeding your Brakes, you will be wasting your time

So also have a look at this Post which describes how to do that

Bleeding The Low Pressure Side of the Teves Mk1V Braking System

 

Thanks everyone for the reply. I had read OrangeBlossoms post and it seemed rather technical for me. I am light on mechanical skills, I guess with owning a classic I will need to role my sleeves up.

The specific issue(s) that I am having are....start the car, no lights on dash and peddle supports braking fine. Get up to a speed and push the brakes, the car will slow, however the pressure on the peddle is a little spongy and then the ABS light on the dash comes on. After some time, seconds maybe, the lights go over and after I take my foot of the peddle pressure is normal again until it happens again which would be a few mins later depending on where I am driving. It’s not a violent pull in any direction as one member suggested, just a spongy feeling. My mechanic, who isn’t familiar with Jags suggested master cylinder issue. However, it doesn’t seem like this model actually has a real master cylinder as other cars know it.

Again, appreciate the help.
Jeff

 

I have been experiencing a problem with the brakes on my 1991 pre face lift convertible which is now sorted. Try this to see if it’s the same problem I had. With the car parked turn the ignition on engine doesn’t need to be started and wait until the accumulator builds up pressure and cut out. Now put your foot on the brake pedal and push don’t pump then let me know what happens. On mine the pedal sank and the the accumulator pump would cut back in.
Rob.

 

As said, there is no master cylinder, just the actuator, which is just a kind of valve setup.

I would say you have a pressure problem.

Run the car, park it up and as said, turn the ignition back on, pump the brake pedal a few times. How many ok ps do you get before the pump activates again? It should be at least around 4-5.

My thoughts are:

1. Pump switching off too early (faulty pressure switch)
2. Pressure leak somewhere (rear brakes, fluid leak, accumulator has a leak)
3. Too smaller accumulator (it needs to be the same size, as it won't keep the correct pressure charge).

 

Hi Robbo

Exactly the same problem on my Car as you know, which I haven't got sorted yet as I swapped the ABS for a Brake Booster which I'm swapping back again! because for one thing I am obsessed with getting it to work, as the ABS on my other Car works perfect

The one thing I'm concerned about is that you said you get only Seven pedal presses before the Brake Pump cuts in, where on my other Car with ABS the Brake Pump Never cuts in, except of course if I stop the Car and turn off the Ignition, as once the system is primed then it stays primed

Maybe you've still got Air in there somewhere?

Not unusual to have to Bleed the Brakes a couple of times but this is a bit of a mystery all the same

 

Hi Alex.
I’m pretty sure my system is now working as intended. My Range Rover P38 worked in just the same way. It also had a failing accumulator and the pump would cut in each time the pedal was pressed. New accumulator sorted that and around 7 brake applications before the pump would cut in to top up the accumulator. Each time you press the brake pedal with these accumulator systems some of the pressurised fluid in the accumulator is used to boost the brake pressure and once the pedal is released that pressurised fluid is returned to the reservoir. After 7 or so brake applications the accumulator pressure needs to be topped up so the pump kicks in.
Rob.

 

Hi Rob

You may be right, so when I get around to it a New Accumulator will be high up on my list but at the moment enjoying the Summer after Lockdown

 

dont discount a ' bulging ' flexible brake hose when braking, sometimes static inspection does not show this up , so inspect the flexi lines with engine running and someone pressing the brake pedal,

just like an MOT inspector does ( in the UK at least )

it could be where some/all the pressure is going on braking

BB

 

How common is that?

Thanks

 

I'm having problems, car stood still it takes about 3 or 4 pumps and the pump kicks in. Is that a problem? Got my anti lock light on all the time but no red light?

 

Just as an update, I got into the car and turned it to start stage 1, I heard both pumps come on and they ran for bit. I started the car and let it run for a bit and pump the breaks as suggested. I got to 4 pumps before the lights came on and the pumps started again. When travelling and I would break, there was a slight pull right but nothing major or violent as suggested. I think that the issue might be pressure as the mechanic when he was installing the new accumulator and the speed sensor only bled the back brakes and not the front....anyone know if that might be part of the issue?

Thanks again all.

 

Hi All,
Just been reading through all of the above, here's link to my test results so far seems to be sufficient forecast of the upcoming failures: https://www.xjsbanger.co.uk/jaguar-x...or-diagnostics
Just don't treat it as serious reference. Pressure accumulator sphere has capacity which is a fraction of operating pressure/capacity of the XJS ABS brake system... Don't touch it if it works, unless you're bored, willing to learn new things and have some caps to do so. 7 brake pedal strokes is excellent! The best what you can get.