XM ABS

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RASCAM
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XM ABS

Post by RASCAM » 09 Mar 2002, 18:37

Trying to sort out the ABS on my XM, RP No. 5077, which is an "H" Reg. I had 3 sensors with 1030 ohms each and a fourth with 1010 ohms. Bought a new on which has 2600 ohms. Citroen tell me there is only one available which is part no. 96 067 694. What's the answer to this one.
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David Goddard
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Post by David Goddard » 10 Mar 2002, 04:28

Good one!
On my Xantia they are 1,050 ohms.
I don't know how the ECU self tests, but I guess that plus or minus 10% would make any difference. I would imaginge that the higher impedence coil you have been sold would work - could well generate a slightly higher voltage. However, the ECU self test MAY "reject" it. Worth a go perhaps. Don't forget that the warning light will stay on until you have driven the car a short distance - and gone round a corner!
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NiSk
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Post by NiSk » 11 Mar 2002, 14:33

Yes, there are two types of sensor for the XM, Bosch or Seimens and I have heard they are not so compatible with each other. However, your original readings seem well within tolerance, so whats the problem? If you are measuring the resistance at the ABS computer contact, then it could be that one of the sensors has moved too far away from the cogged wheel, so you are not getting a sufficiently large signal. I'm not sure of the distance, but its pretty minute.
If your measuring the resitance across the sensor, then I suspect your trouble lies in the cable connector close to the sensor, the cables in the wiring loom or poor contact /earthing of the ABS computer.
//NiSK
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RASCAM
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Post by RASCAM » 28 Mar 2002, 14:23

Thanks Nisk,
Mines an early XM,'91, and it's system is Bendix. The sensor supplied by Citroen is marked Bendix but doesn't even look the same. They tell me there is only one available.
You start the car in the morning and the light behaves as it should. Then it's hit and miss for the rest of the day. I'm pretty confident that it is the self test which finding a fault with sensor but I don't know the answer to why Citroen only have one available
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Jon
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Post by Jon » 28 Mar 2002, 15:23

Just had a quick look at this on the microfiche.
According to slide there is a choice of Bendix or ATE ABS system, with a change to the front sensors with Bendix system at RP5809 (10/92).The ATE type front sensors have no RP break.
The rear ABS sensors are the same whether the system is Bendix or ATE and there are no RP number changes.This is Citroen ref 96067694, so the dealer is correct in saying that there is only one type of ABS sensor for rear of all XM's.
Jon Wood
IT Supervisor
GSF t/as Andyspares
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RASCAM
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Joined: 09 Mar 2002, 18:29
Location: United Kingdom
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Post by RASCAM » 01 Apr 2002, 02:36

Thanks Jon for your efforts. I still haven't got to the bottom of this one. I bought two of the above numbered sensors from yourselves, the second because I thought the first must have been faulty. I can say that they look phisically different to the other sensors on the car. Maybe you could look in your parts bin at bendix front for the above vehicle. The others on the vehicle have a protruding magnet whereas what has been supplied is flat like the CX flywheel sensors. I don't know for sure but I think the difference between front and rear is the cabling as the reistances are similar.
Regards Richard
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NiSk
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Post by NiSk » 03 Apr 2002, 19:49

Oops!
Apologise for mixing up Bosch/Bendix and Siemens/ATE! (Although I'm pretty sure the ABS computer is manufacured by Bosch on my XM). I also suffered erratic ABS errors. It appears that as they get older, the sensors become prone to dampness. On a dry day, they will work quite happily, but after a deluge or even several days of wet weather, thsy generate errors, even though the measured resistance appears the same. As someone else mentioned (I think it was on this forum), the sensors are well nigh impossible to remove, even by force! So there could be some compression damage occuring, the only way to get them out is by drilling (!?)
I have run new cabling to my rear sensors (twice!)the original wiring gave up after about 4 years. My first attempt with twisted standard PVC/copper wire lasted just over a year (!) the salt on the roads over hear (Sweden) really kills copper! I then replaced the wiring with PTFE sheathed silver plated defence-grade wiring and that has lasted over 3 years now.
Oh yes, even the cheap-o wire Citroen uses for signal cables only has a resitance of less than one ohm, and at the signal voltages and currents involved, the wiring (if it isn't damaged) wouldn't have any effect on the resistance you measure at the ABS computer.
//NiSk
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Jon
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Post by Jon » 04 Apr 2002, 20:07

1000 apologies!!!!!!
Looked into this again.
Turns out that there is also Teves ABS, and rear sensors with Teves are different.
Theres also 2 types, upto and after RP7289.
>Rp7289 is Citroen ref 454553, after RP7290 is Citroen ref 454565.
We don't keep either of them as yet, I only just found out about it when I was trying to work out Rascams problem. Sorry guys
Jon
Jon Wood
IT Supervisor
GSF t/as Andyspares
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LHM
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Post by LHM » 24 May 2002, 18:05

Hi Guys!
Came across this forum searching for clues on a similar problem with my XM. I'd like to check the sensor resistances, but the ABS ECU has *two* connectors (one black, one white), rather than the one shown in the Haynes manual. The car is a 1996 2.0 CT Turbo Auto, runs just fine, but the MoT test is looming...... :-(
Does anyone have the connector wiring information for this ECU??
Cheers,
David
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