Technical ABS Light on

[LeftyGreg]

It seems that my wife has registered me and my B for Motorfest in Chelmsford next month, so, this morning, I dug the car out of my garage where it hasn’t done much for the last 21 months due to my health issues which are all sorted now.

As usual, it started straight away once I had charged the battery up which is the good news, but, I now have a month to get it through the MOT, which I thought would be pretty straight forward

However, the bad news is that the ABS light is on constantly

Does anybody know of this is likely to be failure of sensors or could it be something else?

 

[bugsymike]

It seems that my wife has registered me and my B for Motorfest in Chelmsford next month, so, this morning, I dug the car out of my garage where it hasn’t done much for the last 21 months due to my health issues which are all sorted now.

As usual, it started straight away once I had charged the battery up which is the good news, but, I now have a month to get it through the MOT, which I thought would be pretty straight forward

However, the bad news is that the ABS light is on constantly

Does anybody know of this is likely to be failure of sensors or could it be something else?

Can you code read it to locate where fault lies.
If car has been standing it may be a case of rust from brake bridging the ABS rotors giving a false reading.
Note if you have magnetic ABS rotor on end of wheel bearings Do Not Clean With Anything Magnetic!!! Even a screwdriver that has got magnetised can damage them.

 

[LeftyGreg]

Can you code read it to locate where fault lies.
If car has been standing it may be a case of rust from brake bridging the ABS rotors giving a false reading.
Note if you have magnetic ABS rotor on end of wheel bearings Do Not Clean With Anything Magnetic!!! Even a screwdriver that has got magnetised can damage them.

If the code read means connecting to the socket under the passenger side dash then no as the socket doesn’t seem to work (tried with 2 of everything)

I definitely have sensors on the wheel hubs, could it just be that they are dirty? If so, what can I use to clean them, brake cleaner?

 

[bugsymike]

If the code read means connecting to the socket under the passenger side dash then no as the socket doesn’t seem to work (tried with 2 of everything)

I definitely have sensors on the wheel hubs, could it just be that they are dirty? If so, what can I use to clean them, brake cleaner?

If the code read means connecting to the socket under the passenger side dash then no as the socket doesn’t seem to work (tried with 2 of everything)

I definitely have sensors on the wheel hubs, could it just be that they are dirty? If so, what can I use to clean them, brake cleaner?

I don't know what age your model is, but later models have a OBD port ( a D shaped socket near the steering wheel and often just under the dash board) that can be used to read the error codes , this could point you in the direction of which wheel ABS sensor is giving trouble.
A quick search online seems to indicate the Barchetta OBD port is under a cover near the drivers seat, if that is where yours is and not working then it may be a fuse or a bad earth causing it, however ideally it needs to work to get correct information.
It may not be the sensor it's self but the part it takes it's signal from at the wheel, older models used a "hall effect" sensor that read the vanes on back of the brake disc disc or drum etc. to send a signal back to the ABS computer, that type can just be cleaned of any debris that blocks the vanes giving a false reading when compared with the other wheels, later ones used a magnetic disc sometimes as part of the wheel bearing and should be kept away from any magnetic influence.
I am talking generally from experience of other makes of vehicle, I am sure there are Forum members here who can give you specific advice on your model.
Brake cleaner and a soft brush may be enough to clean some, it does depend on the type though.

 

[LeftyGreg]

1995 model, so no ODB socket, just the 3 pin connectors and a lot of confusion

I just hope the ABS light isn’t an MOT failure

 

[bugsymike]

1995 model, so no ODB socket, just the 3 pin connectors and a lot of confusion

I just hope the ABS light isn’t an MOT failure

You haven't been able to find the cause of the ABS light fault? Were you able to check any of the possible causes?
Assuming it is an ABS fault I would have thought that would be an MOT failure.
With only a three pin diagnostic port I am not sure how you could delete a error code once you cure it either, maybe some one else here can advise you.

 

[LeftyGreg]

I was hoping that the ECU would tell me at least which corner to look at and then, once resolved, the light would go out on its own

 

[bugsymike]

I was hoping that the ECU would tell me at least which corner to look at and then, once resolved, the light would go out on its own

In an ideal World you would be able to read detailed information regarding where the ABS fault lays.
What I would do is inspect with wheels off, each brake ABS ring and if nothing obvious there then test the ABS sensors themselves. If you can find and fix a fault then try disconnecting the battery in the hope that being an older set up it may delete the error code, something not possible with later electronics. This in the absence of any good suitable diagnostic tool available for you vehicle.

 

[LeftyGreg]

Thanks @bugsymike battery disconnection has been tested as I had to charge it up off the car

How do I test the individual sensors?

 

[bugsymike]

Thanks @bugsymike battery disconnection has been tested as I had to charge it up off the car

How do I test the individual sensors?

Depending on whether they are passive or active ABS sensors, it should be possible to use an OHM meter to test for continuity on an unplugged sensor, also "active " ones can be checked for a voltage supply to the sensor.
Comparing the readings from the other ABS sensors will hopefully confirm their condition.
I have had to do this on VW Tiguan and Skoda Scout 4x4 amongst others.
However for piece of mind look online for other information to confirm for your own piece of mind as I wouldn't want to give you bad advice as there are many ABS types.
Did you find out if your ABS Rotors were all in good condition to give the instruction to the ABS sensors?

 

[Bobs2293]

ABS light being on is 100% an MOT failure so don’t waste your time putting it in before it’s fixed.