serious ABS problem

[RED1]

Hi all - need urgent advice on this one....

1996 Disco has developed a serious brake problem in that when travelling at walking pace, as if approching a junction etc, the ABS will start to chatter away and I'll lose all braking ability:eek:

This has happened intermittantly about half a dozen times over the last day or two. Haven't noticed any fault when driving at "normal" speeds.

Local garage, who are generally pretty good, had car today and although they experienced the symptom, couldn't identify the cause. Mechanic wasn't too pleased as he just about rode over the mini roundabout:eek:

My nearest LR specialist is about 1.5 hours away and they're about to shut for xmas, so a quick fix there is unlikely although i'll keep fingers crossed.

Anyone experienced this or know the solution?
cheers
Iain

[andymurph]

my guess would be the toothed ring (think its inside the brake disk ha come loose

[lynalldiscovery]

Front ring is built into the cv joint and the rear is inside the disc.

Best bet would to pull the abs fuse then try it and if it stops the fault you can confirm you def have an elec fault.

Nearly all the abs/ebs faults on the trucks at work are sensor related, ie excessive air gap (needs pushing back in) sensor runout (slack bearing then push sensor back in).

Is the warning light on?

Reset all the sensors road test and if fault comes back reset sensors again the one that moves is where to start looking.


Lynall

[sotal2]

If it does it again try taking your foot off the brake and then re-applying the brake

[paulghunt]

hi
i have had this problem on my 1996 300tdi replaced the servo, replaced the vacuum pump, refurbed the whole front axle, changed the abs sensor, problem went away for a short while then happened again when my wife was driving nearly crashed the car. i have been pulling my hair out and spent a lot of money lucky i carry out my own repairs else it would not be economical to repair. the last thing to change was the abs modulator and this has cured the problem. running perfect now

regards Paul

[TEMPL4R]

We get the pedal pulsing at low speeds when the ABS ring cracks and comes loose or the magnatic ring is damaged, It is common on Citroen, Rover and Jaguar.

Check the sensors and rings first, then the Modulator, as Paul suggests. It should log a code anyway, get it read.

Chris

[paulghunt]

i thought that i cured the problem when i stripped the front axle drivers side first as when i took it apart the bearing had gone on the cv which caused the abs light to come on, this was because as the bearing had failed it allowed the cv with exciter ring to run out moving the abs sensor away giving to big of an air gap. The only thing that i can confirm is that the brake fault would not happen when the abs light was on. I am a fairly heavy bloke when you get this brake problem you cannot stop the vehicle no matter how much you jump on the brake. But it will only happen at low speed. With what i have changed on my car i can say that there was a difference straight away when i changed the abs modulator, there are plenty around second hand.

regards Paul

[bananahead]

did the abs light go off when you changed the modulator?

[paulghunt]

I spent a lot of time on my car, i have got to know it well. I have learnt to manually decode the abs faults, which on the origional problem showed air gap to big, i could push the abs sensor in this would put the abs light out but because the bearing had gone on the cv/ stub axle after driving down the road it would come back on. Refurbed this cured the abs light problem. the brake judder and no brakes at low speed did not show any codes when decoded and also the abs light did not come on so it has been a costly process of ilimination.
regards Paul

[bananahead]

only reason i ask is i have had the same problem recently although it comes and goes.

The abs light is mostly always on on my car, so i took it to an independant specialist.. he plugged it in and couldnt find a fault, he manually checked stuff and told me the brakes were fine.

Anyway yesterday i was towing a bit of weight and as i came up to a roundabout i got the old judderry feeeling from the brake pedal and little braking from the car. So i was thinking if this IS the modulator and i replace it, if this will this cure my problem, and will it make that abs light turn off?

[bananahead]

sorry just read about the stub axle.

[paulghunt]

It May not cure the abs light
Thats the problem i have found no real evidence that there is a problem because it only lasts for split seconds. my wife refused to drive the car any more after this happened. i am supprised that if the abs light is on that the independant dealer could not find a fault because i am sure any faults have to be cleared before the light will go out

regards Paul

[bananahead]

it was an independant specialist, not a dealer.

He had the car for a day and i dont think he ever experienced the problem (driving the car with this happening) as it was a rare occurance. But he does have the computer stuff and said it reported nothing, but he did check all the brakes etc... he told me he reset the position of one of the sensors and when you start the car the abs system resets, and when you go over 5mph or something the light will go out. anyway after he had the car this would happen (the light would go out) but would normally come back on, usually after a speed bump or something....

the problem with the judderry brake pedal at low speed would happen with the light off and the light would come back on.