560SL Speedometer and Cruise not working - PeachParts Mercedes-Benz Forum

Neil D · #1 03-01-2006, 10:16 PM

I have a 1986 560SL. I have been doing some engine work (replaced the valve stem seals) and also replaced the O2 sensor. When I road tested it, the speedometer and cruise control are not working. I can't see anyting that I have disturbed that would cause this. After studying the wiring diagram, I checked the fuse in the fuse box (passenger footwell), but that looks OK. I have also pulled the instrument cluster, but don't see anything wrong there. I'm sure this is an electronic speedo, so there's probably a fuse, relay or connection that I have disturbed somewhere.

Does anone have any clues or suggestions as to where I should start?

Any suggestions appreciated as this has me stumped.
Neil

Walrus · #2 03-01-2006, 11:46 PM

May I offer this suggestion: You crawl back under car and look closely at the wiring to the speed sensor on the tranny, then follow it up... You should have an electronic speedo. If the speedo is not getting signal, then the cruise will not work as well (I think). Also, check the fuse with an ohm meter or similar. The speedo must have 12 volts going to it to work.

Good luck!

Neil D · #3 03-02-2006, 08:41 AM

Thanks I will certainly do that. My first thought was that I had disturbed something when changing the O2 sensor. I am not sure where the speed sensor is on the tranny, but its possible its in the same general area. I also noticed this morning that I seem to have developed a transmission fluid leak - so your suggestion may have other evidence pointing to that location.

Thanks for the suggestion.
Neil