ABS Sensors

[Jon441cc]

Having the dreaded ABS light come on after about 1/2 a mile of driving

I've just checked resistance for each of the ABS sensors and its come back with both fronts have a resistance of .978 but the offside rear is coming up with 1.174 and nearside is coming up with 1.128 should they not all be reading the same resistance while static.


cheers Jon.

[S2central.net]

Wouldn't worry so much about a few ohms difference on the sensors... more likely you have a weak signal from one or more of them. They are an inductive sensor that work off magnetic interaction with a toothed wheel on the outer driveshaft. If the teeth are gunged up with rust & grim you get a weak signal... Sometimes a gentle tap with an engineers magic wand (aka a hammer) will push the sensor closer to the teeth and give a better signal. However - be careful with that as the sensors can be stuck rigid after umpteen years and hitting them too hard just breaks them... That and if you push them too far they will come into physical contact with the teeth.

Sorry to say but an oscilloscope is only way to visually compare signals from all sensors to see which one looks different. I think you have an ABY though so the ABS controller should report cause of fault by VAGCOM.

[Jon441cc]

Just given all the toothed rings a good going over with a wire brush and just about to see if its made any difference. Also checked the distance of the sensors to the toothed rings with a feeler gauge and had to give 1 of the sensors a bit of a tap to close the gap

Its a 3B paul so if this does'nt work will have to track down an oscilloscope.

[Jon441cc]

Just been for 20min drive and no more abs light

[S2central.net]

Perfecto... nice to fix something with a wire brush and a hammer isn't it - not so handy for a non-starting engine though - LOL...