Thread: ABS Sensor replacement?

Originally Posted by BIG O

2. If you have, don't jump to the conclusion that the Sensor needs to be replaced like most will say. Also don't jump to the conclusion the wheel hub is shagged and needs replacing like one bloke told me. Take the sensor out of it whole and check for damage, metal filings etc. Give it a wipe. I'm told grease is fine, so it's looking good so far. I went to work next day and bingo they were back, problem still there.

5. Then let the handbrake off, car out of gear and roll the car on level ground and watch that the multimeter reading goes up and down. If it does and if it stays btw the desired resistance levels the sensor is OKAY. This is what I found with mine. So knowing the company line is to replace the whole ABS sensor with the long cable version that has no plug because" the plugs cause problems" I naturally looked at the plug. Its basically a 2 pin connector that is sealed. Pulled the two halves apart and checked. No obvious signs found, although the previous owner must have had a boil over and there was plenty of pink stain around that whole area PINK OAT. The 2 wire connections look like they are brass. PINK OAT eats brass, thats why you can't use the stuff in brass radiators.

No, grease is not fine at all and can trigger a low voltage fault in the system. Its important that any grease which is on the sensor and on the tone ring (looks like a square tooth gear when you look into the hole that the ABS sensor came out of) is completely removed. The grease interfers with the sensors ability to generate a signal, and the thoughts are that the lithium or whatever it is in the grease is the cause of this by reducing what is an already marginal ability for the sensor to produce a good clear on or off signal from the tone ring.

Strange, they should be silvery colour. I thought they were aluminium.

Grease not fine at all!!??? I thought the reductor ring was part of the inner wheel bearing race?? if so grease is going to be there. Anyone pulled a hub apart to tell for sure?. My understanding is that the sensor is merely a magnet, and the magnet picks up the different height of the teeth on the ring. Same as a computer sensor on a bicycle picking up the wheel magnet. Never heard of a magnet being affected by just grease.

Also if you use a multimeter to see the sensor works is definetly not "on or off".
Also I should have said copper, I hope it''s not aluminium, because it sure looks bronze in colour to me, maybe my eyes are going!!

Originally Posted by BIG O

Grease not fine at all!!??? I thought the reductor ring was part of the inner wheel bearing race?? if so grease is going to be there. Anyone pulled a hub apart to tell for sure?. My understanding is that the sensor is merely a magnet, and the magnet picks up the different height of the teeth on the ring. Same as a computer sensor on a bicycle picking up the wheel magnet. Never heard of a magnet being affected by just grease.

Also if you use a multimeter to see the sensor works is definetly not "on or off".
Also I should have said copper, I hope it''s not aluminium, because it sure looks bronze in colour to me, maybe my eyes are going!!

Its the metal which is in the grease we think. Such as Lithium grease etc. I've cleared the grease off mine and fixed the 3 amigos. That particular surface doesn't need lubrication, but had become greased up in my case when some new CV's were being fitted.

There was grease in my hub but this wasn't the problem with mine.

With the hub off and the sensor in place I put it in the vice and wound some rope around the hub and tried to get a voltage reading with a multi meter. But All I got was 0V. With a CRO you can wind it by hand as slow as you like and a wave form will appear. I am told the multimeter won't pick up the signal which is true.

Originally Posted by Gillie

There was grease in my hub but this wasn't the problem with mine.

With the hub off and the sensor in place I put it in the vice and wound some rope around the hub and tried to get a voltage reading with a multi meter. But All I got was 0V. With a CRO you can wind it by hand as slow as you like and a wave form will appear. I am told the multimeter won't pick up the signal which is true.

Won't pick up the signal with it set to volts because it's a Hall sensor. You need to set your meter to continuity or signal mode.
A multimeter will pick it up and an old style mechanical type will do an even better job.


Using Capitals, the difference between helping your Uncle Jack off a horse or helping your uncle jack off a horse...

AFAIK a tad of grease is indeed recommended. NOT ANY GREASE but dielectric grease ONLY, which being non conductive won't alter electromagnetic flow. It will help slide the sensor in place and protect it from corrosion from the outside.

Are the front and rear sensors the same? I have a spare front one, will it fit the rear if needed - short cable plug type.

Originally Posted by jwb

Are the front and rear sensors the same? I have a spare front one, will it fit the rear if needed - short cable plug type.

Just the cable length is different.