Xantia ABS

[tonyjoc]

Hi, Got a problem with the ABS light staying on on my HDI xantia. I've tested each sensor at the wheel end and replaced 2 (1 I broke the other was open circuit) so now I have all wheels with equal readings but when i test at the ECU end only 1 shows a reading. Does anyone know of a plug and socket elsewhere in the loom? Another post reported the same problem some while back but it was never taken up. Please help.
Cheers Tony

[CitroJim]

Hi Tony,

It is a single continuous loom all the way from each sensor to the ABS ECU with only the black 2-pin connectors for the sensord themselves. The loom runs under the car on the nearside along with the hydraulic pipes. It appears to be the same on both the MK1 and MK2 from the information I have.

Check initially that you have the 2-pin plugs firmly home. They're a fiddle and it is hard to tell that they are completely home sometimes.

Is it a front or rear you're having bother with?

[tonyjoc]

Thanks Jim,
I checked all the connections but still baffled. However the good news is that after about 30 mins driving the light went out and has performed correctly since.
Could it have been some stored fault codes not cleared by disconnecting the battery.
Not to worry - a RESULT
Cheers Tony

[CitroJim]

That's good news Tony ABS faults will appear to clear on thier own as the ECU goes through it's self test and put the lamp out but the faults remain stored. I believe that if you disconnect the battery for long enough, the faults will clear completely.

It can be surprising how many intermittent faults can be logged that do not flash up the light but are visible when the ECU is read by a diagnostic tester.

Sensors that look OK on a resistance tester can still be duff and the only way to find them is to look at what the ECU is doing with a daignostics machine such as a Lexia. I had an ABS sensor problem on my Activa. On a resistance test the faulty sensor read 1.3K as against the 1.09K a good one reads. In experimental playing around last night on Xac's car, this faulty sensor would intermittently extinguish the ABS light but even with the light off and all faults from the ECU cleared, the Lexia indicated the wheel with the duff sensor was spinning at 56km/h!

The moral of this tale is that simple resistance measurements are not a fully reliable guide to the health of ABS sensors.

[admiral51]

i could be talking pants again here but i seem to recall someone saying that on S2 the abs light would stay on and only go out once a certain speed had been reached

Colin

[reblack68]

It's 20mph normally. I'm not sure what's happened in this case.

[paulbx]

I too have ABS issues with Xantia 90 estate- Citronjn helped with comments a week or so ago.
I got it checked with a fault reader and 3 wheels report t 0.1 and rear driver side at 0.2. This a very frindly garage nearby they seem to think its the ABS ECU has gone faulty as they felt that all the connections were good

The Light stays on at ignition for about 40 secs then extinguishes - now it just comes on occassionally.


Paulb

[CitroJim]

I got it checked with a fault reader and 3 wheels report t 0.1 and rear driver side at 0.2. This a very frindly garage nearby they seem to think its the ABS ECU has gone faulty as they felt that all the connections were good.

Paul, did you do an accurate resistance check on the sensors? It would, before condemming the ECU as they rarely seem to fail in later Xantias, be most interesting to see if the rear one shows a slightly different resistance to the other three.

It could be just a tad of corrosion in the connector although at the back it's not easy to get to...

[paulbx]

Citrojim

No not looked at resistors will get it up on ramps and see soon

thanks for your wikipedia full knowledge


Paul