There were a couple of recent threads on compasses not working.

Someone recommended unplugging the unit from the rear then replugging it. Then, press the left sided button (dimmer) for three seconds til it say "CAL" then drive in three circles.

Well, it worked for me. I just accepted that the unit was fried.

I always tell my kids, with electronics, if there's a problem that you can't figure out, always re-boot. There you go!

I came here looking just to fix this exact problem! I know this these rear view mirror posts are a bit old, but hopefully I can fix this problem. Mine just went on the fritz recently.

are these factory or aftermarket units?

 

nipper