tach wiring

[smike26]

Ok you guys are the quickest way to solve this:<br />Original tach on a 78 115hp merc.<br />On the tach, light blue,black, gray and red<br />on the shift box green black and white.<br />Pleade advise what wires go where.<br />Red is probably light on display.<br />Black ground....<br />Thunderbolt ign. if that makes a dif.<br />This tach worked originally...

 

[WillyBWright]

Re: tach wiring

blue-light<br />gray-signal<br />red-power<br />black-negative or ground<br /><br />green-signal<br />black-negative or ground<br />white-power<br /><br />I haven't personally seen a green on that harness. So you might want to test between the black and white and then black and green for 12v with the key on before connecting the wires. I wouldn't want to be responsible for blowing your rectifier.