Abs Warning Light On All Time Xm 2.1

[faeonara]

will it fail mot with this light on? any ideas what to look for brakes are fine?

[Bigmixer]

Yes,as far as I know it's an MOT failure. Try checking the connections to the wheel sensors for corrosion causing a bad connection. Or, if you know anyone with a fault reader that should narrow it down to one wheel/sensor.
Bigmixer

[faeonara]

thanks thats a big help..already checked the fuses (
what a daft place the top row of fuses are, in my fusebox
hmm this detector device i dont know anyone (

[stevelangston]

The conectors are a common reason for failure.. Hard wire them all before changing any sensors. I have soldered them all and heat shrinked wraped them. Not had a problem for two years now!

steve

[noz]

Hi faeonara,

Yes the ABS light is an MOT failure. To pass the MOT the light must come on with the ignition and then extinguish 5 seconds or so after the engine starts. Anything else is a failure.

There are two types of ABS fitted to XM's - Bendix and Teves. To identify them look in the big black plastic box on the off-side inner wing. The ecu's for the diesel injection, Hydractive suspension and ABS should all be in there if its Bendix. If its Teves then the ABS ECU is bolted to the underside of the ABS hydraulic block. The hydraulic block is located beneath the battery tray on the near-side of the engine bay.

If you can identify which one you have we can give you further advice on what to do to fix it.

cheers

noz

[faeonara]

as usual i am indebted to you noz, to be honest i wouldnt have known where to look i found two big things in sliders inside the box front one was a valeo (dont ask me) and the rear was indeed a bendix

[noz]

Hi faeonara,

Here's a wiring diagram for the bendix abs system. The wheel sensors are as follows:

155 Nearside (RHD) Front
156 Offside (RHD) Front
157 Nearside (RHD) Rear
158 Offside (RHD) Rear

They should all read approx 1000 ohms using a multimeter set for resistance.

Check for 12v on terminal 2 and continuity to earth on terminals 3, 20, 27, 28. Try for continuity between 21-22, 4-5, 24-26 to see if the internals of the hydraulic block are OK.
All measurements are best and most easily made at the ecu in the plastic box on the front offside inner wing. Disconnec the ecu and test the terminals of the plug with the probes of the multimeter.

The most likely place for failure is the last (only) joint in the cable just before the sensor on the wheel. The joints at the front are mounted on a metal strip attached to the inner wing inside the wheel arch. Only Citroen would put a poor quality joint in the most inhospitable location on the whole car where its subject to water and salt continually.
The rear joints are clipped to the circular subframe at the rear of the car. They are mounted high up and are difficult to get to.

Please let us know how you got on with the measurements.

cheers

noz