I just installed a new dash board in my 85 Camaro. Now the lights for the insterument cluster do not work and the gauges do crazy things. I figure I missed a groud wire or two, but have been unable to find them. Any ideas???

 

I only noticed two underdash grounds on the 85 Camaro harness I put in my friends truck. Most of the grounds are tied into a single ground wire and then I believe the headlight switch ground.
One cause of the problem could be the cluster is not getting good contact with the harness plugs (i.e. dirty contacts).
That along with the cluster loosely mounted causes a similar reaction in my friends truck. The tach will jump, volts misread, certain lights light up etc..