Well, my last reply was full of it. My odometer started working again by itself, while the sensor was still busted. Closer examination revealed yet another odometer gear that is now missing a tooth. So, forget my whole theory in the last post. Look for a gear missing a tooth or two.
I see now that your odometer is running fast which is quite odd. Must not be a missing gear tooth.
Since the speedo and the odo use the same sensor, I now know, the problem must be in the cluster itself. If it were the sensor, the speedo would be running fast as well. I've never studied that circuit, but checking for bad solder joints and old bulging capacitors is a good start. It might just need a couple new caps. Really hard to say without having it on the bench. On the plus side, these clusters are readily available at boneyards. I just picked up a really nice one this weekend at Pick N' Pull for $25.
1990 300SE "Corinne"- 145k daily driver - street modified differential
1988 560SEL "Gunther"- 190K passes anything except a gas station
Last edited by tinypanzer; 10-11-2010 at 04:05 PM.