after market tachometer on 92 Jeep Cherokee (XJ)

[Yamaniac]

The instructions tell me to hook up on negative side of coil. So, On my coil, there is a green/red wire which is + from alternator. Also a black wire. problem is, the wire is about 2" long and I don't know if it is even the right one. the wiring diagram does not show the black wire at all. I sure think it is the negative wire, but without knowing, I don't think I want to pierce the thing and cause myself any trouble.

Anybody had experience putting a tach on a Cherokee?
Thanks

[Bud Manley]

I'd look at the manufacturers web site for insight as to exactly what the black wire is.
If you don't every time your gas gets low your power antenna might go up.

[randy]

If the gree/red is + then the black MUST be negative.