tac not working

[71chargerrtclone]

I have tried three tac's and none of them work. I'm even hooked them up in the engine bay, negative on the coil and the other connection to 12vdc. I have electronic ignition.  Thanks

[A383Wing]

what "type" of electronic ignition? What type of tachometer?

A little more info would be helpful here. Did you connect the ground wire as well?

[71chargerrtclone]

Okay it was a bad ground. That must be my problem with the dash lights not working too on my new wiring harness.

[Ghoste]

Oh yes, it all has to be grounded.  You weren't testing this stuff with the cluster out of the dash were you?