ABS and red brake light on

[mgj11]

Today my ABS and Red brake light can on. I checked the brake fluid level which was still fine (hadn't gone down). Brakes where ok for a couple of miles, but then went very hard and I had very little stopping power ( luckly only a few hundred yards from home). Any help would be greatly appreciated

[davidr]

Does your car have the Teves braking system? If so, it could be that your accumulator pump has stopped working. This pressurises a nitrogen-filled sphere that assists the braking system and is an alternative to a vacuum servo.
Sometimes they stop working just because the brushes have worn a bit and stuck. A sharp tap on the motor often fixes the issue.

[Brakebuster]

i agree , first thing to check will be the sphere for the reservoir ,

a little expensive to obtain , very easy to change, but in the grand scheme of things its better than loosing your brakes

however

even with the issue you have , you should still have standard non assisted brakes on the front , hence the reduction in performance

i would suggest you do not drive the car until the issue is fixed , as 2000kg hurtling towards solid objects isn't good for anyone

BB

[davidr]

Having looked it up now, a 1992 car will have Teves ABS system. There is a round accumulator sphere and pump motor mounted in the engine compartment on the bulkhead on the passenger side.
When you turn the ignition on can you hear the motor running? It should run for a few seconds only. If it's running for a long time switch the ignition off and don't use the car as you'll burn the motor out and that will cause you wallet pain.
As mentioned before, if the pump isn't running try giving it a tap to move the brushes.
After that, check fuses.
If the motor runs for more than a few seconds then the accumulator sphere may be the issue and you'll have to replace it.
Hope that helps
David

PS. The reason your brakes worked for a while after the red light came on is that there was still pressure in the sphere. Thinking about this my money goes on your pump not working.

[poprivet]

You should hear the pump motor running when the ignition is turned on and the brake pedal is pressed a few times. The motors have been known to burn out if ran for too long which can happen if the accumulator ball looses pressure.

Some XJ40 had the same pump/accumulator which may help you find a replacement. Spheres can be recharged by Pleiades if the diaphragm is intact.

[ptjs1]

mgj11,

Assuming you have no brake electronic issues, if you get both of the lights illumnating in use, then you've got a fluid or boost pressure issue as mentioned by the guys.

The ABS is complex and you need to understand how it works as it's not really intuitive at all. Read through the section of the workshop repair manual which will give you a really good insight into how all the components work together, plus the list of the 32 electric diagnostic tests.

Assuming it's a pressue issue (more likely), then it's usually down to the pump, the accumulator or the relief valve. Start by determining if the pump is working at all. If not, then check fuse (possible but not usual). assuming the pump is running and generating proper pressure, then it's likely to be an accumulator or PRV issue. Don't do what some owners do and just start replacing any of these expensive components until you've really confirmed that it's faulty.

Good luck

Paul

[mgj11]

Thanks for all the advice. I checked the motor this morning it does switch off, gave it a tap as suggested, this seems to have fixed the issue and the pedal started to work as normal and the warning lights went out. Gave it a test run and the brakes worked as they should.
Will this be a temporary fix, should I get some spare parts ready for when the lights come back on?
Thanks for all the help

[davidr]

Don't you just love a quick fix?!! Cost was acceptable too!
I think what's happened is that the brushes have worn in the motor. They are spring-loaded and should move down to maintain contact as they wear. If they get stuck then obviously they don't move and contact with the commutator is lost and the motor stops working. Give it a tap to shock them loose again and contact is restored.
My 1989 V12 did the same thing a few years back and this was the cure - haven't touched it since and still working fine.
Hopefully it should be the same for you.
Regards
David

[ng4xjs]

I had exactly the same on my 1994 4.0. Also did that, tapping etc. However ended up with new sphere and pressure switch, which cured the issue.

Nick

[mgj11]

Yes I think I may go down that route as it's happen again a couple of times.

[ptjs1]

MGJ,

Can you give us some more detail about the symptoms?

Reset the lights (battery disconnect for 15 mins). Then start car. Does pump run then cut out? If so, when pressing brakes, do you hear pump cut in frequently or only every now and again? When pump runs, does it cut out after a few seconds or run for periods up to and beyond a minute? When warning lights come on, is pump running at that point? If you turn off the ignition, wait and restart, do both lights illuminate without the brakes being pressed?

I'd strongly suggest that you don't buy these (rather expensive) parts until you really know wherein lies the problem.

Cheers

Paul

[Brakebuster]

don't forget , that after clearing the code, the car needs to be run on the road so each ABS sensors ( all 4 wheels ) can be seen by the ECU , otherwise it will throw codes again

i think it has to be over 20mph from memory

but i agree with everything Paul says


BB

[mgj11]

The pump was completely dead didn't run at all, I've replaced it with another pump, which cuts in and out as it should.
I've taken it on a short test drive and the brakes seem fine and the pedal as it should be, no warning lights.
I haven't as yet bled the rear brakes is this essential after changing the pump?