How to Wire a Tachometer?

After market tachometers have a switch on the back of them to select 4, 6, or 8 cylinders. Make sure this switch is set to the correct position. Locate where you want the tachometer located and mount it. You should have four wires connected to the tachometer. I am using the wiring diagram and wire colors of an Autogage tachometer. Connect the white 12 v (+) dash light wire to your dash lighting. The red wire should be connected to the ignition so the tachometer only has power when the ignition key is in the on position. Black is your ground wire and should be connected to a good engine ground. Green connects to the (-) pole of the ignition coil. If you have an aftermarket ignition system it will have a tachometer connection or wire equipped with it. For more information look here: