My tachometer has stopped working on my 1986 911 Cab, is it a sending unit, or the tach itself. The upshift indicator on the tach is working, but the needle is not moving. Any insight would be great before buying one.
Thanks, Matt Southerland

 

There's no sending unit. The signal comes from the Motronic control unit.
Check that the tach wire from pin 21 of the Motronic unit using a ohmmeter.

 

My 86 has the same issue however, the tach will work for a while, then quit, then work fine, then quit again. From my understanding, there is a poor solder in the circut board. My local wrench said he could fix it if I take the tach to him. Just have not gotten around to it. Also, there are a couple of place in Cal that can fix it. North Hollywood speedometers is one I think.

Good luck!

 

As a very satisfied customer, I can recommend Hollywood Speed and Clock. Excellent work.
regards,
Steve

 

Avoid sending off a good tach, as some suggest, before it's determined to be the problem.

 

My 1985 Cab tachomoter stopped tonight during drive home. Can I measure the voltage coming for Motronic unit while it's operating ? I assume the other side of tach is grounded. but diagrams should missing references. Glenn