92 rear anti-lock light

[philetus2]

The rear anti-lock light will stay off for weeks and then come on for a few weeks and then go back off. It's been doing it for the last four years. Now I have to do smog and it's on more than off.
I pulled the sensor out and cleaned it. I pulled the rear end cover, cleaned out the old and filled with new gearlube. I even gave the cover a nice silver paint job.
If the sensor was bad it would stay off all the time or can they be intermittent?

 

[Curious Hound]

There isn't much that can go wrong with the sensor itself. Not saying it can't fail. It just doesn't seem likely.

If loose, it might not read. The sensor must be within a certain distance from the toothed wheel in the diff. too far away - no reading. Too close - wheel hits and ruins sensor.

I would be looking for loose connections, broken wire, or maybe a problem with the ABS module.

Pretty sure painting the diff cover won't fix it.