ABS Sensor - How to narrow down

[treybrad]

ABS Sensor - Which One? Updated...

So I just picked up my '02 p5 w/ 82k. The ABS light wasn't on when I picked it up, but it came on during the hwy trip home. It goes off and on, can't really make a pattern out of it... ie - when it's cold, rainy, etc.

The !brake! light never comes on, so I'm sure it's not a fluid issue. My pads will need changing in the next 5-10k mi, but I don't think that's it.

From searching I think I've narrowed it down to a wheel speed sensor. Is there a way to test them so I don't buy the wrong one? I HATE taking my car to a dealership... but I don't want to buy the wrong parts. Searching tells me they aren't interchangeable...

Thanks for any help,

trey

 

[treybrad]

Ok, after dealing w/ this for the past few weeks I've noticed a few things...

The ABS light will come on and stay on until the car starts moving. After that it goes off and all is fine. ABS works, no light. As long as I stay in the city and don't go > 70mph, it's fine. But like magic, as soon as I go over 70mph, on comes the ABS light. After that, it stays on until I restart the car. Weird.

Does that help narrow down anything? I resets itself everytime you turn off the car. I replaced brake pads and rotors and took a look at the sensors up front, didn't seem like there was anything wrong with them, but I don't know what I'm looking at really.

Anyone have anything to help me narrow this down?

trey

 

[TheMAN]

make sure all of the tires are the same size, relatively even wear pattern, and inflated properly

then check the wiring to the wheel speed sensors, if they are any knicks, cuts, etc on them, then there's your problem... check also to make sure there's no debris on the sensors and that there isn't excessive clearance between the sensor and the sensor rings on the wheel hubs

if you can't find anything else, then it's best to have this looked at by a shop or the dealer

 

[treybrad]

make sure all of the tires are the same size, relatively even wear pattern, and inflated properly

then check the wiring to the wheel speed sensors, if they are any knicks, cuts, etc on them, then there's your problem... check also to make sure there's no debris on the sensors and that there isn't excessive clearance between the sensor and the sensor rings on the wheel hubs

if you can't find anything else, then it's best to have this looked at by a shop or the dealer

Hmm, my tires were shot, but just had them replaced this morning (Kumho SPT!). We'll see if maybe that fixes it. After that I'll look for dirt or something around the sensors.

Thanks,

trey