How to wire a tach

I have a aftermarket tach that I want to install in my '91 nissan sentra. It has three wires, red, black and green. If someone could tell me where and how to hook up these wires it would be greatly appreciated.

Most storebought tachs connect to the distributor. Look under/around the distributor cap for connections.

OK, I'll try to help you:

when I had an electronic tach in my previous car, it had 4 wires: distributor coil (not the coil itself, but a small wire at its side, I'm not sure whether your car has it), ground, ignition (+), and lighting (also +).

Hope this helps. I can't really see how a tach can be wired with just three wires, unless there is no light in it or there is no ground wire and you need to ground the tach itself...

Are the wires the same length? I would think that black is either ground or light... Experiment.

Don't you have a wiring diagram you could scan for us so that we could help you?

Originally posted by Colin
I have a aftermarket tach that I want to install in my '91 nissan sentra. It has three wires, red, black and green. If someone could tell me where and how to hook up these wires it would be greatly appreciated.

Red = constant 12v source
Black = ground
Green = negative side of coil. In a 91 Sentra I am showing that wire to be green with yellow stripe

There should be a blue wire too, this is for tach illumination. You can either hook this to ignition or parking light wire.

I got it. Thanks for your help. I found the green wire with the yellow stripe, hooked it up to that and it worked. Now I have to figure out how to mount it to my dash but that is just a minor problem.