New rpm tak

So I just bought me a rpm tak.
got everything hooked up, but it's not showing me the rpm's..but on my coil it's showing both of them are running positive..Idk what the hell I did wrong. Any ideas where I can hook the wire up to besides the coil..?

The feed for the tachometer comes from the coil negative terminal. Power for the tachometer should be tapped from a "switched-on" fuse at the fuse block. Mine's a SunPro tach.

Yeah I did connect it to the negative side of the terminal, the ground is working because it lights up. it's just not reading it. all is there a bypass I can do?

Did you connect the positive power lead to switched-on positive at the fuse box? That you didn't mention.

I got it all figured out. Thanks for the info. Working like a charm now