ABS Warning Light Staying On!!

brmartyn · Post by **brmartyn** » 07 Feb 2010, 13:21

HELP!!!!

I have just driven home from town and my ABS warning light came on and now will not go out!!!

On looking in the Xantia's Owners Handbook it says - 'if the ABS light stays on or lights when driving, the ABS computer has detected a fault and has disconnected the ABS system. this does not affect the normal braking system, the function of which is the same as a vehicle without ABS. Nevertheless, it is recommended that the vehicle be taken to a Citroen dealer as soon as possible.'

They is no way I'm going to a Citroen dealer about this so they can charge me a fortune!!

Any advice please?

Cheers guys

spider · Post by **spider** » 07 Feb 2010, 13:37

Check fuses (including any in the engine bay) , unlikely but if one of the fuses supplying the ABS unit failed, it may count that as a fault.

Next step would be to find someone with a diagnostic machine who could read the real fault (Lexia I'd guess) and then work from there.

It may be something simple such as a damaged sensor (or full of junk etc) or a wire to said sensor. Diag check will confirm the reason.

Old-Guy · Post by **Old-Guy** » 07 Feb 2010, 13:47

A common ABS problem with Xantias is poor connections to the sensor. If you take the car to a garage, the ABS ECU will probably show a wheel sensor fault; garage changes expensive wheel sensor - problem may or may not be fixed. Even if it is, there may well not be anything wrong with the faulty sensor, just unplugging and cleaning the sensor connection fixed the fault.

It's likely to cost you around £50 just to get the fault diagnosed.
However, in my limited experience, the O/S/F sensor is the most common culprit. the cheap test is to unplug the ABS ECU (ignition OFF!), and measure the resistance of each sensor with a multi-meter. The high one will be the faulty connection. At the same time check the multi-plug connections too!

If you search the forum, you will find lots of threads on the subject.

brmartyn · Post by **brmartyn** » 07 Feb 2010, 13:54

spider wrote:Check fuses (including any in the engine bay) , unlikely but if one of the fuses supplying the ABS unit failed, it may count that as a fault.

Next step would be to find someone with a diagnostic machine who could read the real fault (Lexia I'd guess) and then work from there.

It may be something simple such as a damaged sensor (or full of junk etc) or a wire to said sensor. Diag check will confirm the reason.

Thanks for the advice spider I've checked the fuses and they are fine. It looks like I may be contacting Citrojim and asking to borrow his Lexia

Post by **Peter.N.** » 07 Feb 2010, 15:01

You can check which sensor is not connected from the plug into the ECU, the Hains book should tell you the connections.

Post by **xantia_v6** » 07 Feb 2010, 15:23

Peter.N. wrote:You can check which sensor is not connected from the plug into the ECU, the Hains book should tell you the connections.

Don't trust the Haynes BOL for that! Mk1 and Mk2 have different pinout. A search of the archives here should fine the info.

Does the ABS light flicker a second or two after turning on the ignition, and then stay on? That usually means a sensor resistance fault has been detected. If it doesn't flicker, it could mean a fuse or ECU problem.

Old-Guy · Post by **Old-Guy** » 07 Feb 2010, 15:25

Peter.N. wrote:You can check which sensor is not connected from the plug into the ECU, the Hains book should tell you the connections.

"Should", but doesn't - Haynes' Xantia BoL is a 'Service and Repair Manual' not a 'Workshop Manual' - an excuse for being incomplete?

However someone did post diagram and and a photo some time ago.

Post by **admiral51** » 07 Feb 2010, 15:29

Have a look at this topic

Colin

Post by **Peter.N.** » 07 Feb 2010, 15:29

Ah, the XM one does, is it the same ECU?

Xaccers · Post by **Xaccers** » 07 Feb 2010, 16:37

Fingers crossed it's a front one that needs changing as they're dead easy

brmartyn · Post by **brmartyn** » 07 Feb 2010, 17:43

xantia_v6 wrote:
Peter.N. wrote:You can check which sensor is not connected from the plug into the ECU, the Hains book should tell you the connections.
Don't trust the Haynes BOL for that! Mk1 and Mk2 have different pinout. A search of the archives here should fine the info.

Does the ABS light flicker a second or two after turning on the ignition, and then stay on? That usually means a sensor resistance fault has been detected. If it doesn't flicker, it could mean a fuse or ECU problem.

The ABS light stays on. The fuses look fine also. Looks like it could be the ECU

brmartyn · Post by **brmartyn** » 07 Feb 2010, 17:47

admiral51 wrote:Have a look at this topic

Colin

Good topic Colin thank you. Only thing is I have to confess I'm a bit of a novice when it comes to cars and from looking at the pics it looks a bit too technical for me to be tackling!!!

Give me a computer any day and I'm well away ha ha!

Stempy · Post by **Stempy** » 07 Feb 2010, 18:46

Also look here

http://stempy.dnsdojo.net/~stempy/Xanti ... es/abs.pdf

Post by **CitroJim** » 07 Feb 2010, 18:58

Xac wrote:Fingers crossed it's a front one that needs changing as they're dead easy

Rear ones are a doddle if you drop the rear subframe down a few inches

Post by **Peter.N.** » 07 Feb 2010, 19:15

brmartyn wrote:
xantia_v6 wrote:
Peter.N. wrote:You can check which sensor is not connected from the plug into the ECU, the Hains book should tell you the connections.
Don't trust the Haynes BOL for that! Mk1 and Mk2 have different pinout. A search of the archives here should fine the info.

Does the ABS light flicker a second or two after turning on the ignition, and then stay on? That usually means a sensor resistance fault has been detected. If it doesn't flicker, it could mean a fuse or ECU problem.
The ABS light stays on. The fuses look fine also. Looks like it could be the ECU

Well, I know its right for my car because I have used it.