1975 Johnson 70HP OB--Add a Tach??

harley909

Cadet
Joined
May 25, 2003
Messages
21
Hi,<br />I have access to many used marine tachs for my boat. The motor and control box are orig 1975 units. I know I have seen a spare grey wire in the control box. I have no idea if it is connected at the motor end.<br />Is there anyone that can tell me how a tach gets wired into this system or if it is even feasible. I assume it all gets wired back to the control box (throttle and ignition switch location) and doesn't have to go all the way to the motor. If the grey wire is not hooked up to the motor where should it go? (point on the power pack)<br />Any help to this "greenhorn" would be appreciated.
 

OBJ

Supreme Mariner
Joined
Dec 27, 2002
Messages
10,161
Re: 1975 Johnson 70HP OB--Add a Tach??

Harley....the gray wire is the tach signal wire. Tachs usually have three connections. One is marked "I" for ignition or 12V power source, one marked "G" for ground and the other marked "S" for signal. That's where the gray wire goes.
 
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