ABS Fault after broken front spring.

Hello Fellow Citroen owners,

Just before Christmas my front suspension spring snapped on the drivers side breaking the ABS wife in 3 places.

I took it to the garage and had a new spring, ABS sensor and wheel baring fitted. Since then the ABS light still coming on. Also the speedometer fluctuates to begin with but settles after the abs lights comes on.

What’s wrong with my car guys?

Welshcitroen wrote: ↑Wed Jan 01, 2020 6:57 pm Hello Fellow Citroen owners,

Just before Christmas my front suspension spring snapped on the drivers side breaking the ABS wife in 3 places.

I took it to the garage and had a new spring, ABS sensor and wheel baring fitted. Since then the ABS light still coming on. Also the speedometer fluctuates to begin with but settles after the abs lights comes on.

What’s wrong with my car guys?

Hi

It is interesting that you had a new wheel bearing fitted for a broken spring.

The ABS sensor takes its signal from the wheel bearing.

You should check the signal from the wheel sensor when the wheel is off the ground and a oscilloscope on the sensor leads to see if there is a clean signal from the sensor as the wheel is turned.

It is possible to compare left side with right side signals to see that they match in waveform.

C3CAR wrote: ↑Wed Jan 01, 2020 7:22 pm

Welshcitroen wrote: ↑Wed Jan 01, 2020 6:57 pm Hello Fellow Citroen owners,

Just before Christmas my front suspension spring snapped on the drivers side breaking the ABS wife in 3 places.

I took it to the garage and had a new spring, ABS sensor and wheel baring fitted. Since then the ABS light still coming on. Also the speedometer fluctuates to begin with but settles after the abs lights comes on.

What’s wrong with my car guys?

Hi

It is interesting that you had a new wheel bearing fitted for a broken spring.

The ABS sensor takes its signal from the wheel bearing.

You should check the signal from the wheel sensor when the wheel is off the ground and a oscilloscope on the sensor leads to see if there is a clean signal from the sensor as the wheel is turned.

It is possible to compare left side with right side signals to see that they match in waveform.

The garage changed the wheel baring thinking this might be the cause of the problem. But they also tried 2 different ABS sensors also.

They think when the spring went through the ABS wire that it might have sent a shortage to to ECU.

Welshcitroen wrote: ↑Wed Jan 01, 2020 7:31 pm They think when the spring went through the ABS wire that it might have sent a shortage to to ECU.

It is very easy to inspect the wiring of the ABS wheel sensor to look for damage and evidence of potential short.

I think the garage has already answered your question and have done some diagnostics by swapping the wheel bearing and the abs sensor.

Looking at the waveform from the ABS sensor at the ECU will help prove if the sensor or ECU is at fault.

C3CAR wrote: ↑Wed Jan 01, 2020 7:47 pm

Welshcitroen wrote: ↑Wed Jan 01, 2020 7:31 pm They think when the spring went through the ABS wire that it might have sent a shortage to to ECU.

It is very easy to inspect the wiring of the ABS wheel sensor to look for damage and evidence of potential short.

I think the garage has already answered your question and have done some diagnostics by swapping the wheel bearing and the abs sensor.

Looking at the waveform from the ABS sensor at the ECU will help prove if the sensor or ECU is at fault.

they connected it to a machine and the wheel where the spring and abs had been replaced was coming up as going 407mph where the other was doing 20mph

Also lately when I’m breaking not every time it feels like the breaks are skipping or juddering and I don’t slow down as quick as usual

Welshcitroen wrote: ↑Wed Jan 01, 2020 9:37 pm Also lately when I’m breaking not every time it feels like the breaks are skipping or juddering and I don’t slow down as quick as usual

It isn't safe to drive with defective brakes. You have noticed a change in the braking and it may get worse.

I would take it to a different garage to have the braking checked.

The ABS and spring change won't affect braking skipping or juddering so it sounds like something is very wrong, an inspection of the brake discs, pads and callipers are due.

Welshcitroen wrote: ↑Wed Jan 01, 2020 8:05 pm they connected it to a machine and the wheel where the spring and abs had been replaced was coming up as going 407mph where the other was doing 20mph

You have obviously had the garage diagnose the ABS fault with the tests they did. It is not possible to do these tests over a forum.
If they have diagnosed the ABS ECU and you are not happy with that diagnosis, then ask a second garage to look at it for a second opinion.

Welshcitroen wrote: ↑Wed Jan 01, 2020 7:31 pm
They think when the spring went through the ABS wire that it might have sent a shortage to to ECU.

The ABS sensor is basically a coil of wire, so shorting it out shouldn't damage the ECU.