I searched around, didn't find quite what I was looking for, thought I'd just ask. I'm dealing with a super funky gauge cluster in this '86 z28 I picked up. It is a 145mph unit in there.

Speedo/odo, volts, and oil pressure works fine. Fuel gauge is working, but bounces around erratically when driving (my guess is a bad sending unit).

The tach is the main issue, it's all the way to the right and bounces slightly to the left when you start up the car. Does not move when you rev the engine at all. The temp gauge also does not move and is stuck all the way up.

Looking for suggestions on how to diagnose the cluster and if it can be saved. I'd rather not shell out $$$ for a new one, especially if it's not the dash itself that's causing the issue. Not quite sure where to start here. Thanks!

 

Crap. Reposted in electronics. Please delete this.