abs sensor testing anyone know how?

[dodge1979]

Using espritmon im getting a fault from my osf abs sensor. Ive tookit out, cleaned thd face and refitted. Still showing a fault after reset. Does anyone know how to test the sensor itself to see if its faulty or is it a case of fit a new one and see...

[andydclements]

Is it not identical side to side so that you could swap left with right and then check if the fault moves or remains?

[dodge1979]

Thought about that, however I have another factor of the abs ring itself. There seems to be a slight run out of true when you spin the hub. So it almost has the effect of moving closer and then further away from the sensorn is there a specific gap to he maintained? The sensors have shims in between them and the hub to adjusts to suit....

Thought about that, however I have another factor of the abs ring itself. There seems to be a slight run out of true when you spin the hub. So it almost has the effect of moving closer and then further away from the sensorn is there a specific gap to he maintained? The sensors have shims in between them and the hub to adjusts to suit....

[alan]

The best way of testing the sensor and the ring is to use an oscilloscope to display the actual signal / waveform. Ideally the measurement should be made from near the ABS controller so you eliminate any issues with wiring. See here for more details: http://www.picoauto.com/tutorials/diagnosing-abs.html (I should disclose thats my own web site).

If you do not have access to a scope or someone locally with one then Andys advice is sound as it eliminates a possible cause. The changing gap you mention is also a worry - check for worn wheel bearings. There is a specific gap to maintain, but I dont have the manual on this PC to look it up.

[dodge1979]

Oh the bearings are fine. Everything is brand new...it just looks like the ring is deformed. It wasnt noticable when I had all the components apart for powder coating, only noticed it when I spun the hub round on the car looking at the gap.

[Vulcan Grey]

you didn't powdercoat the ABS ring did you?

BTW, Nice write up Alan!

[dodge1979]

No no, that is clean of any coating! Obviously I wouldnt get a pick up if it was coated! Now when I cleared the fault and had adjusted the sensor closer to the ring, I noticed whenever I pressed the brake there was a lot of clicking noises going on. Constantly. These dont happen normally with the abs fault present. Also, the brakes felt worse than with the abs not working. Im debating whether to remove the whole setup and go with something else...

[fflyingdog]

Did you powder coat the abs ring carrier? as the coating could hold the ring out of true.Another point may be when you adjusted the sensor closer to the ring it(Abs Ecu) wasnt sensing the gaps so your abs wasnt picking up the correct signal, basicaly it was reading it more of a continuous ridge rather than a upy downy type thing(I may have made those words up),what does the book say for a min/max gap from sensor to ring?

Edited August 23, 2011 by fflyingdog

[dodge1979]

No the ring is clear of coating. Ive got to check tye gap required, but im suspecting tyd fault is caused by the slightly out of shape ring..

[KVJ 786]

Hi

A while ago I had the ABS fault light up. I used Espritmon and it reported the OSF sensor too. Got a new one fitted it and fault gone away. Best to replace the sensor as for the age of it I would not trust it anymore if it failed. Afterall it for the braking system and ABS is useful when activated in case of hard stopping.

Cheers

Ameer

[Passmore928]

Hi Dodge,

The gap between the sensor tip and pole wheel (ABS ring) should be between 0.6 - 1.4 mm (0.024 - 0.055 in).

This gap is pretty critical. If you don't have access to an oscilloscope to measure the waveform, you can always use a multimeter with a min / max function.

I had a similar issue on my GT3. After replacing a suspected sensor, I picked up that the signal was infact inconsistent.

After a thorough cleaning of the pole wheel teeth with a wire brush / screwdriver to remove any corrosion between the teeth it all worked fine - even with the 'old' sensor - typical!

Hope this helps!

Passmore