Pre 1994 XM front wheel ABS sensor

[Keith10]

Hi All I am looking for a front wheel ABS sensor for series 1 (Y3) XM pre 1994 it's the one with green plug. Original was a Siemens 31112, Citroen number on the cable is 96161385 as far as I can tell it a littlle faded on the last number. If anyone has one or can source please let me know. Many Thanks Keith

[xmexclusive]

Hi keith

Type "Citroen XM ABS sensor" into ebay to get a number of results.
There is only one Bendix (Seimens) Green plug one currently on offer NOS (new old stock).
A front one at an asking price of £159.99 post paid.

It has been on offer without takers for some time.

You will notice a fair number of new Teves (ATE) Blue plug front ones for £45 or so.
While these will physically fit all XM's they have no adjustment and the sensor sits further from the ABS ring than the Green plug one.

This distance difference can halve the signal seen by a Bendix ABS ECU.
Not ideal when the Bendix ABS has borderline reliability.

If no one else offers one in a week or so send me a PM (personal message) and I will look and see if I can find a working recovered spare.

John

[citroenxm]

Im low on a stock of these so sadly cannot offer one up at the moment..

Untill i know EXACTLEY what i have im not letting any go... Sorry..

[Ocellia]

Are the Ser 2 ones cheaper? (Better?)

[xmexclusive]

As explained elsewhere on here all Mk1 XM's and early Mk2 XM's were fitted with Bendix ABS.
Later Mk2 XM's were fitted with Teves ABS. Change over was ORGA 6741.
My post above covers the costs and technical differences between the sensors for the two systems.
There are also design differences between front and rear sensors for both systems.
For electrical signal reasons it is not advisable to fit front sensors from either system in the rear position.

John

[Ocellia]

John; I appreciate the time you've patiently taken here! I'm still researching the minutiae of XMs as a potential new owner! (AS a long time Citroen owner, I'm aware of their habit of changing stuff randomly-your knowledge is valued!)

[Keith10]

Hi Guys

Thanks for you responses much appreciated I do believe that the series 1 Y3 securing bracket could be modified if you have a series 2 Y4 sensor and grind down the mounting to allow the sensor to be closer eg: 1 mm as required. Beware the sensor should be tested and check the ABS light on the dash before doing so. Or alternatively a new modified bracket to compensate. Also bearing in mind the ECU versus the resistance of the sensor it must be possible to add a series or parallel resister in line to meet the requirements of the ECU. I don't have a variable resistor with designated resistance readings but it must be possible. Any ideas guys.Regards Keith

[xmexclusive]

Adding a resistance to a sensor will not work.
When the ABS ECU is doing the static start up test it checks the sensors by measuring their resistance.
When the vehicle is moving above 4 mph without the brake applied the ABS ECU regularly monitors the signal generated in the sensor coils.
Adding resistance to the sensor circuit will cause this test to fail.
A few repeat failures and the ECU will put the ABS out of use and the dash light on.

The sensor heads on most designs of later Mk2 sensors can have the material removed to seat a little deeper.
This is better than grinding material from the top surface of the mounting hole.

All three types of ABS ECU (Early & late Bendix, Teves Mk4) see and pass low resistance sensors in the static start up test.
Late Bendix ABS ECU is the only one that can handle and accept the unique high resistance Bendix sensors.

John