ABS sensor costs and sourcing

[MikeT]

I know this goes against what I've read on this forum but when I bought the car the ABS light did not illminate at all (I didn't even know it had ABS!) until I replaced the fuse
Now I find the light comes on permanently and stays on until the ignition is turned off, indicating a fault.
Using the helpful posts here I unplugged both front connectors under the car, gave them a good cleaning and refitted them several times to no avail.
I then followed the ECU plug test procedures and got appx 1030 ohms from both offside sensors but no continuity at all from both nearside sensors.
I rechecked my findings several times but could have easily made the same amateur mistakes!
Presuming there is no continuity, am I correct in assuming it could be a wiring/plug fault as much as it can be failed sensors? Is there a one-man test to determine where the fault lies? Where can I get the best deal on new sensors and what should I expect to pay? Is it worth the time and effort of hunting breakers yards, dismantling and testing used sensors or shall I just bite the bullet and pay a mechanic to sort it?

[CitroJim]

Mike, it is my betting you have two duff sensors although it is faintly strange both on one side have gone. It could be a bit of damage in the loom that is common to these two sensors.

Check each suspect sensor again nearer the sensor itself.

Each sensor is connected to its loom via a plug about two feet away from the sensor. Break here and check continuity again.

The front sensor plugs are well tucked up under the subframe. The rears are as well but access is poorer.

Front sensors can often be rescured from a scrapper with a bit of care but rear ones can almost never be recovered due to them being well corroded in place.

[MikeT]

Mike, it is my betting you have two duff sensors although it is faintly strange both on one side have gone. It could be a bit of damage in the loom that is common to these two sensors.

Check each suspect sensor again nearer the sensor itself.

Each sensor is connected to its loom via a plug about two feet away from the sensor. Break here and check continuity again.

The front sensor plugs are well tucked up under the subframe. The rears are as well but access is poorer.

Front sensors can often be rescured from a scrapper with a bit of care but rear ones can almost never be recovered due to them being well corroded in place.

Hi Jim, I tried to test the front sensor at the connector but the connector half I need to test is locked in place (under a load of oily crud), pointing upwards and it's impossible for me to see the pins let alone get my probes on them. Do you know how they unclip? As I read the rears are even more difficult to get to and having large hands, I gave up at that point. GSF want £90 for both - that's half what I paid for the car - do you know anywhere cheaper? Better still, can they be repaired? Thanks.

[BrianM]

Connections on the rear sensors joints is a fumble about and see what comes apart job - when you get the connector apart make sure to tie a piece of string on for getting the new one back up through. Access is very limited for getting the rubber grommet back in place over the rear training arm. I ended up taking the back box to get a bit more room - and that was me in a pit doing it !

Brian
97 Xantia TD
(95 Xantia TD & 93 Xantia TD - Resting at the moment !)

[MikeT]

Thanks BrianM, good tip about the string! Just don't fancy paying so much money for the sensors. I need a new back box so could combine the jobs.

[MikeT]

ABS ECU reads failed N/S/R sensor yet my ohms testing of the ECU multiplug says both front and rear - so I'll take the mechanics word for it and trust his diagnostic equipment. However, I cannot see the sensor from underneath and therefore cannot trace the wiring to clean the connector! I found a cable coming from the wheel area and followed it with my fingers into a box section/frame but my hands won't go in and I have no idea where it goes from there let alone feel any connector. Does anyone have any illustrations showing where I'm to look/feel or are my hands simply too large for the job?

[TehAgent]

Have a look here, just scroll down the page

[MikeT]

Thanks TehAgent, but I should have been more clear, I need to clean and check the rear nearside sensor/connector. The link you provided looks more like the front one though I'm not certain.

[TehAgent]

MikeT,

for the rear sensors, the best way to gain access is to remove the rear wheels, then follow the cable that way, as from under the car, they are protected and hidden by a rear guard plate, the cable should go up into the wheel arch then into a plastic tray that is mounted on the underside of the car, if my memory serves me correctly

[MikeT]

Thanks TehAgent, I admit I was too lazy to dismantle anything - including wheels - due to back pain. If I can get good pointers, I tend to make more of an effort.

[Hurdsey]

I've still got this if your interested.

http://www.frenchcarforum.co.uk/forum/v ... hp?t=21566

[MikeT]

Thanks for the info Hurdsey, but the ECU diagnostic is showing rear nearside ABS fault.

[TehAgent]

Well if you didn't live on the south coast, an was a bit closer, i woulda come and had a look at it for you, I'm pritty sure i woulda been able to get the bugger off with out wreaking it, and replace it with a scrap yard one,

Hurdsey, are you sure that is a ABS sensor, i ask as Citroen up here in Northampton are selling ABS sensors for £104, though a trip to the local scrap yard yielded 2 front ABS sensors, for £0 and ones on my car and working fine.

[MikeT]

That's a highly tempting and kind offer TehAgent. Sure I can't tempt you to a trip to the seaside...free ice-creams and a beer or two?
I'll take a look tomorrow with the wheel and guard off. Got any tips on removing a seized-in sensor as I'm likely to have a go anyway? Thanks!

[Xaccers]

Roadtrip!