Another tach question

[FJ_Russo]

I'm sure this has been asked and answered already, and I'm sorry for asking a question that I'm sure is in the archives but I cant find a definitive answer.

I have a 1975 85hp V4 Johnson. I want to install a tach, I think I have figured out I need a 6pole tach, I have also heard there is a possibility that my remote unit will have a grey wire that I hook direct to the tach? Is this the case?

I'm not really sure at all what I need to with a tach this is completely new territory to me, but hey I'm here to learn so if you have a moment please bestow some knowledge on me

Thanks!

 

[Dhadley]

Re: Another tach question

Depending on which control you have it may even have a plug in for a tach harness. Regardless, the wiring should be at or near the key switch. Yes, you need the grey wire. The tach will also need the purple (key on - 12 volts) and a ground. If you want the light in the tach to work you can tie that wire to the running lights or to the purple.

 

[Silvertip]

Re: Another tach question

Check the control box just below the ignition key. If you see a three terminal rubber receptacle there, that's where the tac harness plugs in. The harness will not come with the tach but it was available here on iBoats in the past and maybe still is. If you are not good at wiring I suggest you go that route as it will be a plug & play installation. If you know basic electronics, than locate the referenced wires and wire accordingly. By the way -- you don't need a 6 pole tach. You need a tach for a 12 pole alternator. 12 pole alternators produce 6 pulses which the tach must count. An adjustment on the back of the tach can be set for the number of pulses.

 

[FJ_Russo]

Re: Another tach question

Ok so 12 pole 6 pulses, I read a post on a year newer same engine that said I needed a tach that was capable of reading 6p. I thought that meant 6pole but it was probably 6 pulses. So 12 pole tach capable of reading 6 pulses. Now I went on a hunt for my grey wire today and am unable to locate. I dont have the plug and play option you speak of silvertip and Dhadley, but I can wire it for sure, if I can locate the magical grey wire lol.
Here is a shot of my control box, I have a red and white wire coming out the back end that do not go anywhere, those are the only loose wires i have. So does that mean the grey wire would be inside the control box?