[ted b]

We just finished putting the dash back in my sons 70 SS and everything works but the Tach. It was originally a idiot light dash which we changed to full factory guages. Wiring seems correct. Does anyone know some diagnostic tips to check to sees where the problem is? Thanks, Ted

 

[Coppertop]

Ted-
Did the tach work before it was installed? This seems stupid, but devices of this vintage often times go bad and need to be rebuilt.
Only things I can think of is check to see if it has a good ground (-) connection, it is receiving power and make sure the actual wire (I believe it is brownish tan) that goes to the coil is connected. Also you didn't mention if you have stock points or you're running HEI, this makes a difference on things to check.

 

[michael j]

The tach is wired seperately from the printed circuit board that fits on the back of the gauges pod.

Coppertop is close, it uses a dark brown wire the routes independantly through the firewall to the coil. When I converted mine I used one of the plastic push-in retainers that hold the firewall insulation pad in place as a conduit. I just snipped off the pointed end and fed the wire through.

Are there any other funky things happening to indicate on overall ground problem in the dash?