Tach Problem
 

Hi , Tach was working perfectly ('87 944S) until I replaced the odometer gear. Now when the engine starts, the tach reads about half what the idle speed is ( approx. 500RPM) I have cleaned all the connections I can think of ( including the three wires in the tach itself)--always the same.All the other guages work fine. The one connection I didn't look at is where the ECU cable connects to the main wiring loom--couldn't find it-is it inside the cabin, or on the engine side of the firewall?
So, am I looking at a new(used) tach or ?????
Thanks,
Jeff

When something I'm working on is ok, then after I fix something in that area something stops working, I tend to look at what I moved/changed. I would stay looking in the instrument cluster area. With all other lights and things working correctly, I would assume you have all connectors put back in the right places, but make sure the white tabs have the connectors locked on and tight. If that doesn't work, then maybe check out the tech section of this site and they have an article on parts to clean to make instrument clusters work better.