my shift light has only two wires red and yellow i thought they were supposed to have three wires i have a red wire on the back of my tach that is a power source when i crank the car so im guessing it goes to the red wire on the shift light then i touched the tach signal wire with the yellow wire and revved up but no shift light any ideas i took the tach apart but those are the only wires no third one (sorry about the punct. but i was in a hurry)By the way I have a MSD DIS-TACH ADAPTER on my 02 GT
You need to make sure your model of tach has a shift light output. Usually if they do,it is just a plug in with the corresponding pplug on the light. You may need to send an e-mail to the manufacturer to carlify your specific case.