hey guys ive been tryin to get this stupid tach to work in my car for a week now and its really pissing me off!!! its a auto gauge and it has 3 wires a black-ground a green-tach and a red-power. my car is a 92 civic and ive placed the tach wire just about every where people say to!!! some one please help!!! thanks

 

Tap the green wire to wire A21 of your ecu. Should work and if it doesn't, it could be the tach that is the problem.