Strange electrical problem.....I replaced the non-functioning tachometer with a good unit purchased on eBay, should be a straight forward, easy replacement. The replacement tach had no ground lug on the backside as there was on the non-functioning original so I soldered one to the housing in the approximate location of the original. Hooked up everything, tach works great but as soon as you turn on the ignition the temp gage pegs at full HOT (all the way to the right) and stays there. Do some research on this forum and discover I might have a shakey ground connection (a known problem), Pull it apart again add an aux ground still the same problem. Pull the ground wire off of the tach and the temp guage and the tach work great but now I don't have any light in the tach at night! Why can't I ground the tach? Looks like I can have the functioning temp gauge or the Tach lights?? Any ideas??
Car is an '84 944 5-speed
