Hooking up Tach

[rustyscrew]

I am trying to get a tach from my old mercury engine to work on the newly installed evinrude 120hp (1988-v4). I believe it should work. Problem is the previous owner played with the wires a bit, so it is hard to know if things are hooked up properly.

I read 24 volts AC across the A and B ports on the binnacle when the engine is idling. Does this sound right?

When I hook it to the tach, it doesn't work... I could be just hooking it up wrong though.

thoughts?

thanks

 

[Joe Reeves]

Re: Hooking up Tach

What are the terminals marked on the tach (B, G, I, Whatever) or if no terminal markings, what color are the wires that protrude from the tachometer? Also is there a dial with numbered markings on the back of the tach, a switch that can be set to different numbers? Describe the tachometer.