Ok I got this new tach and I looked at the instructions and it show where every wire goes except for the one the gives it the rpms of the car my car is a 1998 dodge neon highline there a black ground, red 12v, white light, and green which is the tach meter wire the instructions say look at the owners manual it dnt say nothing. The car is dizzyless to its coiled so i need to find the wire it said that the wire looks grey and light blue

 

your really just hooking up that electric supercharger right?

j/k there should be a wire to splice it to if you take the cluster out of the dash there should be a blue/green wire.