ABS light

Hi everyone,
Ths is my VERY FIRST post here, so be gentle with me.
I have a C3 Picasso 2009 model, and last year i had the off side front bearing replaced. After i left the garage the ABS light came on, so i took it back and the mechanic said that it was probably a faulty sensor. So i bought another one and went back. They replaced it but the light came back on, but they didn't know why. Anyway my car recently failed its MOT due to this light being on, so i paid more money to see if the bearing was in the right way. It was and i refitted another ABS sensor, but after a hundred yrds or so the light comes back on. The mechanic reckons its the ABS module and would be expensive. My question is. Where can i find the ABS module and test it before i buy a used unit? I've searched everywhere on my car but i cannot find it. I dont even know what it looks like. I'm a fairly decent hands on amateur mechanic but i'm stumped with this.
As usual any help at all would be appreciated.
Thanks everyone.

Hi

If you fit the bearing the wiring way round, the ABS light will come on just after driving it. So having that checked first is the right thing to do.

Don't guess these things. It gets very expensive, very quickly that way.

Look for a signal from the ABS ECU to see why you are getting a fault. Use lexia/diagbox to see the ABS signals.

I have had poor ABS signals from dirty sensors, but having the sensor changed means that's not the fault you have.

The ABS ECU is part of the ABS Hydraulic block.

The ABS hydraulic block is usually found behind the front bumper on the side of the master cylinder.

Also fitting a non magnetic bearing in place of the correct magnetic bearing will give the same fault - that is, the ABS light comes on just as you drive away from the garage.

C3CAR wrote: ↑Sat Jan 23, 2021 7:10 pm Hi

If you fit the bearing the wiring way round, the ABS light will come on just after driving it. So having that checked first is the right thing to do.

Don't guess these things. It gets very expensive, very quickly that way.

Look for a signal from the ABS ECU to see why you are getting a fault. Use lexia/diagbox to see the ABS signals.

I have had poor ABS signals from dirty sensors, but having the sensor changed means that's not the fault you have.

Hi C3 Car Guru,,
Thank you for replying to my concern.
Yes i and the mechanic did check that the magnetic side was facing the sensor. I don't want to spend hundreds of pounds on an ABS module and pump when it could be something else. I've got an OBD scanner, so i'll see what that shows up tomorrow or Monday.
It's very frustrating as you probably know, but once i find the problem AND find the ABS module i'll be a little happier.
Thanks again.
Regards

C3CAR wrote: ↑Sat Jan 23, 2021 7:34 pm The ABS ECU is part of the ABS Hydraulic block.

The ABS hydraulic block is usually found behind the front bumper on the side of the master cylinder.

Also fitting a non magnetic bearing in place of the correct magnetic bearing will give the same fault - that is, the ABS light comes on just as you drive away from the garage.

Hi again,
does this mean that i'll have to take off the front bumper to get to theABS hydrolic block?

Thank you

It could be as simple as the abs rings corroding. This happened twice on the rear brakes of our 2011 car. It would certainly be sensible to take it to someone to get a diagnostic run. They aught to be able to pinpoint the fault, and it could be a cheap and simple fix.

Bigtoe wrote: ↑Sat Jan 23, 2021 9:01 pm Hi again,
does this mean that i'll have to take off the front bumper to get to theABS hydrolic block?

Thank you

No. You can gain access from underneath and/or removing the LH/nearside/passenger side wheel arch liner. However I agree with the others and believe the fault lies elsewhere and you should get the car scanned to see what it's complaining about first.

routemaster1 wrote: ↑Sat Jan 23, 2021 10:01 pm It could be as simple as the abs rings corroding. This happened twice on the rear brakes of our 2011 car. It would certainly be sensible to take it to someone to get a diagnostic run. They aught to be able to pinpoint the fault, and it could be a cheap and simple fix.

Thank you. I will definitely have a look into this.
Thanks again. I've been pulling my hair out and my knees are knackered too.

Ozvtr wrote: ↑Sun Jan 24, 2021 1:18 am

Bigtoe wrote: ↑Sat Jan 23, 2021 9:01 pm Hi again,
does this mean that i'll have to take off the front bumper to get to theABS hydrolic block?

Thank you

No. You can gain access from underneath and/or removing the LH/nearside/passenger side wheel arch liner.
abs 002.jpg

However I agree with the others and believe the fault lies elsewhere and you should get the car scanned to see what it's complaining about first.

Brilliant. Thank you.
They say a picture paints a thousand words.
I'll see what the diagnostics machine says, but i will have a look at it.
Thanks again.

Regards