Two wire tach for 70hp johnson

[blikesit]

Hey guy's, I have a 1979 70hp johnson. I want to add a two wire tach (which I already have) I know the black wire is ground but I have no idea where the other wire goes. Help please!

 

[boobie]

Re: Two wire tach for 70hp johnson

What model tach is it ?? The tach signal on the mtr is the gray wire for use with OMC tachs which runs off of the charging system.

 

[blikesit]

Re: Two wire tach for 70hp johnson

What model tach is it ?? The tach signal on the mtr is the gray wire for use with OMC tachs which runs off of the charging system.

its an OMC tack off a 1974 70hp. Sorry it took so long to reply, had to leave for a bit. I'll try the grey wire.
Thanks for the info.