Tachometer Wiring

[Tman]

I was trying to figure out why the Tachometer on my rig wasn't working. When I laid under the dash, I noticed that only 2 of the four wires are hooked up. It is a Sport-Comp "Monster" 3980 standard ignition Tachometer. 4 wires (black, red, white, green). The green is run through the firewall into the engine comp., the black is terminated under a screw on the bottom of the dash, grounded I guess. Anyone have any info for me? Thanks

 

[yak67]

I'm thinking red would be a power source to your ignition, not sure about the white, maybe for light?

 

[Tman]

Could I put the Red right to the ignition, where the stereo wire is connected to the stud on the back of the ignition switch?

 

[73stallion]

should be able to, yes. red for power, black for ground, green for signal from negative side of coil, white for light. sounds like someone wired it so the light comes on with the key.

 

[Pokey71]

mine that i just put in is. red to key power, black to ground, white to light switch, and green to the (-) side of the coil

 

[Tman]

Cool, done, thanks guys.