abs light on dash

The most common reason is a failure of the speed sensors on each wheel, have you had any work done to the wheel bearings, brake disks or driveshafts recently? It could be something as simple as a dirty connection between the sensor and the wiring harness.

Chris

A gubbed wheel sensor. Damaged wiring or a dodgy connection to a wheel sensor.

Not recently, no. Are these connections readily visible, and where would they be located, please?

The message from "Lofty." contains these words:

Dicky sensor. Probably either not getting a proper signal because the rotor's teeth are clogged or its not aligned, or it's got a loose connection.

The message from "Lofty." contains these words:

They're usually not in the wheelarch 'cos it's too hostile. They're often inboard of the wheelarch. Find the ABS sensor on the hub and follow the wire.

Well, if you tell us what car you have somebody here should be able to let you know where the connectors are if they are on that particular model. You can get a readout from the fault codes held in the cars computer, that should help pinpoint the exact fault. Your dealer can do that for you or there are readers available or also usually a DIY solution involving counting the number of flashes from the mil lights on the dashboard.

Chris

Thanks. 1988 Citroen BX19GTI, so no computer fault codes available apparently. Should local garage be able to check for the possible connection problems or do I want an auto electrician?

It is quite likely to be the front nearside wheel sensor, it gets all the crap from puddles and stuff. A thorough googling on BX ABS problems pointed me this way and was exactly right in my case.

There is a way to check them with a multimeter I think, but I can't remember what it is. An auto electrician would definately know.

The wires are coaxial and the front connectors are inside the engine bay by the wheelarches, trace the wires back from the wheel sensors and you'l find them, approximately below and behind the battery and up the side of the timing belt cover.

The connector is translucent plastic, is about 2cm diameter and about

Front sensors are held in by a single 10mm bolt into the hub carrier.

Rear sensors apparently don't come out as easily and often have to be destroyed if you want to remove them but they are fitted in a similar arrangement on the rear radius arms. Trace the wires back to find the connectors

While you're fiddling, have a go at cleaning the crap out of the toothed ring and off the face of the sensor and see if it's as simple as that.

Sensors are very expensive for what they are new, available from GSF car parts or Euro car parts I think, I got one from a breaker for cheap.

HTH

Thanks, Douglas for this comprehensive info - The sensor from the scrapyard worked OK then?? I note the comment in another post that chassis numbers are relevant to some of these sensors.

I took a chance on a scrapyard ABS sensor, I don't remember if it was a NSF or OSF sensor I robbed, but the donor car was newer, lower mileage and diesel powered. It worked perfectly till I sold the car earlier this year.

I don't know whether chassis numbers are relevant to ABS sensors on BXs, as far as I'm aware they all use interchangeable brake components except the 16v which uses ventillated front discs and has fatter calipers (which take the same pads).

GSF only lists 2 types of sensor for the BX, front ones and back ones. ~£50 each.

Any scrapyard BX with ABS will do.

Thanks again.