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Full Version Unusual Abs Problem On 2.5td

Club XM Forum > XM General Issues
jackyboy
I fitted a new front N/S sensor about 2 years ago and it's been fine. I replaced the front discs and pads at the same time but found that If I crawled to a stop, just braking lightly, the brake pad felt as if it was loose. It transmitted a sort of rattle/clonk through the brake pedal. If I braked with any sort of pressure no problem. Any way it sailed through it's MOTs and I assumed it was a lazy caliper which I needed to change at some point. The car had also been standing for a few months.

A month ago I drove down to Essex and while there I parked on the seafront. When I reversed out of my parking spot I had to put the car on full lock and on doing so up came the ABS light. When I drove it with the ABS fault on the front brakes operated normally and at speed the brakes were noticabely better. Switch the car off and back on, no ABS fault and the lazy caliper type problem returns.

Now when I start the car on a morning the abs light doesnt come on until I turn the steering wheel. Once it comes on the brakes are fine no clonking.

Any ideas?????????

NB Noz, is your offer still open to me. If so, can you tell me the GSF part numbers for the belt and the tensioner, I'd hate to arrive with the wrong parts.

Cheers Jim
citroenxm
Could well be a fault in the hydraulic block?

I had a Xantia that when braking slowly, it would release the brake just upon stop solid, it was quite scary...

A cure, a replacment hydraulic block, this fault also came up on a friends M reg 406 Mi 16 some years ago, this also was fixed with a new block and was reported to have been a falty release valve in the block...

Seems to fit as you say if the light is on and the abs is disabled it performs fine, so this would indicate this similar problem to me too...


Good luck

Rgds

C
xmexclusive
Hi Jackyboy

From your description I think you might still be looking at two separate faults. Citroenxm might well have explained how they appear to be linked. I would be inclined to check out the wheel arch cable on the front sensor that was not renewed. To take a while for the ABS light to lock on then clear on next start up I think is likely to be caused by the occasional loss or misreading of a sensor signal. The ABS ECU counts these faults and after a certain number is programmed to switch the ABS out as the sensor signal are deemed unreliable. Heavy lock might be flexing a partially broken cable. An ELIT readout that confirmed this might be useful. I think Noz mentioned someone with access to an ELIT.
I would also be inclined to check out the front calipers for movement freedom. There are a few threads on the site about how these calipers can be obstructed mechanically. The condition and freedom on lock of the handbrake cables where they come through the steel eye at the bottom of the front struts might also be worth a check. Only then would I start looking at the calipers themselves then the ABS block after that.

Regards

XMexc
xmexclusive
Hi Jackyboy

Have just had a look at your signature and see that the ABS is a BENDIX so it might be worth bleeding the ABS block as this often gets overlooked. Haynes covers it well. There are two AF nuts on the outside of the block that allow the fluid to bleed internally when loosened.

Regards

XMexc
robertmnorton
Hi jackyboy ,i would tend along xmexclusive's thinking.I had a similar ocurrence on my 2000 vsx 2.1(teves).The fix was ultimately a L/H/F sensor wiring repair due wire breakage inside the insulation where the harness routing had been pulled across the auto g/box end plate behind the wheel arch plastic mud shield.
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