Anyone ever have to replace an ABS wheel sensor??

[Soleman20]

I think one of mine is going, ABS comes on for no reason.

[eeyore]

I've never replaced one on a Nissan, but here's the general overview:

1. if the abs is coming on for no reason, then yes, one of the sensors thinks the wheel isn't turning any more. The sensors are generally long-lived and don't often fail.

2. it'll either be an optical sensor or a magnetic pickup.

3. If it's magnetic (looks like a bit of plastic), make sure it's positioned correctly. Normally there'll be a screw thread that will run the sensor in to about 1-2mm of a toothed disk. Any more than 1-2mm will cause the sensor to start failing (and hence think the wheel isn't moving). Of course, any less and you'll shear the head off it. If the positioning looks ok, then it's probably knackered. The way to set these is to run the sensor right up to the disk, then back it off 1/2turn (i.e. so that it's as close as possible without actually touching).

4. If it's optical, make sure the lens is clean! Some systems use a combined emitter/detector which shines onto a reflective strip. Make If this is the case, make sure the strip is clean. Other systems use a seperate emitter/detector shining through a toothed wheel. Again, make sure both lenses are clean. Again, change it if everything looks ok.

Testing these sensors is a bit of a bitch without the appropriate equipment. Magnetic sensors can sometimes be tested with a DVM set to resistance. Wave a piece of metal past them and look for a change in resistance. Problem is that it really depends on the DVM, since you'll actually be using the voltage from the DVM battery (it's a frig, but can work). optical sensors normally require a seperate power source and a DVM set to voltage.

Hope this helps, sorry it's a bit theoretical, it's come from an R&D background rather than in-service.

[Soleman20]

I appreciate the info. BTW, the car will sometimes disable the ABS system causing my dash light to come on. I went to my mechanic when the light was on but he told me that only Infiniti has the proper diagnostic tool to get the code for the problem. I can't see paying 1 hours labor charge just to tell me what my problem is...

Any clue how much the sensors cost?? It might be worth it to replace it all together. I say "it" because a few days ago I was driving and I hit a small pothole (nothing bad) on the right front wheel and at that exact moment, I saw the ABS light come on.

[nismo_gt]

Originally posted by Soleman20
I think one of mine is going, ABS comes on for no reason.

If its intermitant,then its more than likely a dirty/rusty sensor
You'll really need to take the wheels,calipers & discs off to
check properly & if they're not obviously dirty, gently clean with
a wire brush.
If no better then you'll have to get a garage to find which
one & then get it replaced (they're a bitch to get out after they've
rusted in so let them do it) & I paid about £100 for a sensor for my old P10 eGT

[eeyore]

Sounds like the sensor may be loose/dirty.

Silly question, but have you checked your brake fluid recently??

Sorry for that, but it's always worth starting with the cheap/easy bits first!

[Soleman20]

Fluid level is fine....

[nismo_gt]

Its time to get those wheels off then