Xantia V6 ABS

[fastred]

Sometimes, when braking gently from low speed, the ABS on my V6 kicks in on dry roads, so that the car comes to a juddering halt. The rest of the time the brakes behave perfectly, and the ABS warning light goes out as it should.

I assume that there is a problem with the sensors or the ABS ECU, although I notice that there is some corrosion on the serrated wheel which signals to the sensor. Will try a good clean of this and the sensor first, but would be grateful to hear if anyone else has met this and solved it.

If it helps, the ABS worked well on the icy roads back in January.

TIA

fastred


2000 Xantia V6 Exclusive

[citroenxm]

No..

It wont be sensors or ECU, as yours is a late car, its MOST likely the ABS Ring on the drive shaft, it will have rusted through and will have a split gap and will be loose on the CV joint..

Seen this many a time on S2 cars...

I have sucessfully fix the problem.. I removed the ABS ring, cleaned the rust off the CV joint and the ABS ring, refitted it so the gap met and spot welded it in place with my MIG... been fine ever since..

Paul

[P616VKX]

Are you sure it's the ABS kicking in? It's just that I've never had my car juddering to a stop, even with full pressure on the brake pedal... The abs makes a clicking sort of noise but Xantia's don't judder around like other cars...

I'd be thinking it was a warped disk.

[citroenxm]

No yoU know the difference between brake release and a wobble from a warped disk... It will be the abs ring.... They are only bad on s2 cars....

Paul

[RichardW]

Got the same on my MK2 HDi....and yes, the NSF ABS ring is split. If / when I have the shaft out I will try Paul's trick - otherwise you can buy a new ring and shrink fit it to the joint.

[fastred]

Great diagnosis, guys, thank you very much. OSF ring is split - looks as if a tooth is missing, although this may just be because the ring has opened up.

Two supplementary questions:

Is the ring actually moving round (I can move it by hand but it is quite stiff with rust) or is the "missing" tooth causing error signals to be picked up by the sensor?

Is there a simple way of de-activating the ABS until I can find someone to weld the ring up for me? Richard's idea of shrink fitting a new ring would seem to require more dismantling than I am prepared to take on.

Thanks again,

fastred

[citroenxm]

It will be the missing tooth/gap causing it.... Unplug the ecu plug under the bonnet just behind the battery... Lift the red clip and the plug comes away....

Paul

[RichardW]

It's probably that the ring has opened up, and the ABS is seeing an extra tooth, meaning it thinks that wheel has slowed more than the others, hence kicking the ABS in. You will need to get the shaft out of the hub to clean / weld it up anyway, and the new ring fitting is only heat the ring up with a blowtorch, then shove it on and let it cool. As it's the OS shaft it will be easy enough to do on the car - but in any case since it's a V6 you don't need to worry about disturbing the shaft and losing the gearbox oil as they run dry If you've got a 35mm deep socket, breaker bar, 21mm deep socket, and ball joint splitter, getting the shaft out of the hub is only a 15min job

[mongoose100]

Is there a simple way of de-activating the ABS until I can find someone to weld the ring up for me? Richard's idea of shrink fitting a new ring would seem to require more dismantling than I am prepared to take on.

Thanks again,

fastred

Either unplug connector to ABS ECU or remove ABS fuse, that will then turn into conventional braking system - Warning light MAY stay lit up on dash too...