Sometimes my Service ABS light comes on after starting the car and driving a short period of time (long enough for the self test procedure). Sometimes it won't come on and everything's fine.

Seems I read once that this is usually caused by dirty sensors at the wheels, and all I need to do is pull them and clean the stuff off them. Is that right?

 

That would certainly be a logical first step. I had a knock sensor do the same thing on my 92 and it turned out to be caked with oil and grime. A coupla' shots of WD-40 later and a cleared ECM, and it was good as gold again. :cheers:

 

Definitely start with cleaning them off. Don't use something like brake cleaner on them as they are in a rubber boot I believe.

 

I would start by pulling the code stored in the Electronic Brake Control Module (90 and above store codes). Good chance it's a sensor. The codes will really help start the trouble shooting process. Should it be a sensor, you can remove the sensor from the top side of the car (front ones anyway). Just wipe them clean and make sure you don't loose the little O-ring. I would then take a light and see if the reluctor is clean, the teeth can get grease and other debris, especially if the wheel bearing is heading south. (Different code) The sensors are essentially non adjustable. Also make sure the little brackets holding the wire in place is properly mounted. The system is sensitive to EMI. If sensor code returns, trouble shooting chart says replace the sensor, even if the Ohms check 900-1100 (believe tha's the spec). New sensor for my 90, Right Front, was around $60. As it turned out, the right front sensor circuit was bad on my 90 and a used control module fixed my problem. (New control modules are around $1100-crazy) Hope you get yours fixed with less trouble. Let me know if you have any more questions. I spent lots of time working this system.

dlmeyers 90 coupe zf6 3 speed shocks