Abs Out Of Use Showing On Display - CITROEN XM Internet Reference

92 ABS OUT OF USE showing on display.

The brakes
92 ABS OUT OF USE showing on display.
Has anyone cheaply corrected the fault indication of 'ABS OUT OF USE'. This indication is common in
all XM's, even the latest, and appears without rhyme or apparent reason. Many months and thousands
of miles/kilometers may pass between appearances and it quickly corrects itself when the car is next
used.
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One of the ABS sensors is faulty. THe only solution is to replace it/them. The wire is worn but sometimes
the connection is just O.K. It's not safe to drive with a worn ABS sensor. I CAN TELL YOU!! I KNOW!!!
Arthur
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I don't know very much about the ABS-system, so I think I'm missing the point; Why would it be
dangerous to drive with a worn sensor? My sensor is worn, and I'm planning to cut the wires and
connect them with a 1000 ohm rheostat.
As I see it all that could happen is that the ABS would really stop working, and then I wouldn't know
about it. I'll just drive more carefully (which you should always do).
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Thank's, I guess I'll by a new sensor instead of by-passing it.
Am I right when I conclude that the sensor is not just sending alarms, but it also takes active part in the
braking?
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If the sensor is faulty, the ABS computer receives wrong signals. One of the odd things that happen is
that ABS starts working when nothing is wrong at 5 MPH. This appears often when braking and taking
corners at the same time. Then again, only when doing 5 MPH.
I replaced my sensor 16 months ago and never had the problem since.
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The sensor sends pulses as the wheel rotates, allowing the ABS unit to determine the wheel's rotation
speed. If you simply short the wires to the sensor the ABS unit will think that the wheel is locked, and
release pressure to the brake on that wheel to try to get it rolling again.
Fortunately the ABS unit is smart enough to quickly understand that when it still doesn't get pulses from
the sensor, the sensor must be broken. (It has to be, otherwise a sensor fault could easily lead to
disaster). It will have to make this discovery anew each time the ignition is turned on however, as it uses
this "event" to reset itself (in case someone fixed the problem when the ignition was off).
DISCLAIMER: I don't know any details of the ABS system in the XM; what I've described here are
merely general working principles.
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I really do feel that the fault expressed by Glyn Roberts on 16 October is an 'air in brake circuit' problem.
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