Citroen XM Forum

Spotted on LBC in France. I think this is Bendix, and if so looks like a bargain.

According to the fiche, using the part number the seller provided, S1 from ORGA 5819 (without note) and S2 Bendix up to ORGA 7108. Front.

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Pity the sensor head is not clearly visible.

I believe that pre ORGA 5819 the XM Bendix used low resistance (1200 ohm) sensors.
All XM Bendix sensors produced after 5819 were high resistance (2600 ohm) sensors.
The XM Bendix ECU was changed at the same time to see both high and low sensors but not the resistance gap in between.
Early (xxxx001) and late (xxxx002) XM Bendix ECU's are interchangable so any remaining early ECU's should be replaced if you fit new sensors.
If not you risk chasing non existent ABS faults to get rid of the warning light.

While Bendix ABS was fitted to a few later XM's the only model so fitted was V6-24v's from ORGA 6742 until 7108.

John

So to clarify John, if you fit a later Bendix sensor to a pre 5819 model, you need to fit a later ECU for it to work properly and the new ECU will work with the old low resistance sensors. ?

Not quite Russ.
For your "work properly" read "work at all" .

The original Bendix XM ABS was designed towards the end of the first flush of ABS on some high end production cars.
They managed to avoid very expensive delights like sensor rings machined onto brake disks.
They chose instead to use sinusoidal rings on the front driveshafts with a standard sensor of around 1100 ohm.
Theory suggested this arrangement would give the best electrical signals from the sensors.
It was not perfect in service so well within a year a belt and braces solution was evolved.
Square toothed wheels on the drive shafts and unique double coil sensors to give much bigger electrical signals.
The ECU software had to be rewritten to deal with high resistance sensors on the front and still make the ECU see the old stuff as well.
Dare I mention costs and publicity of a recall avoided too.

Potted history of how we ended up with very expensive unique electrical spec sensors.

If you are fault finding on an XM Bendix ABS read and double check the part numbers on all the components.
Particularly the ECU.
If you find an early xxxx0001 one remove it and attack it with a hammer.
That or play innocent and Ebay it as rare essential spares for early cars.

John

Will do. Thanks for explaining that John. I was just intrigued for possible future reference. Mine seems to be behaving at the mo.

here is what service citroen show

MK1

96 161 385
NFP
AV
- SINCE RPO 05810

MK2

96 161 385
NFP
WHEEL ABR SENSOR
AV
- UNTIL RPO 07108

regards malcolm