I have 1996 twin 150 Mariners. One tachometer quit working. If I switch all of the wiring to the other tach, it works. So I know it is not the gauge itself. I ohmed out the signal wire from the motor to the console, and the wire itself is okay. What is the circuit board box on the back of the motor that gray wire comes out of?? Do I have to replace this box in order to get a good signal to the gauge?? This part looks expensive, and I bety most places let you return electrical parts. Any ideas??
