hooking up 1 wire tach

[craveman85]

My boat has a 1 wire tach from the previous but unknown Johnson motor. The boat I took my engine from (1976 75 HP 3 cyl Johnson 75elr76) had no tach. Where would I hook the tach wire on my engine. There's no tach plug in my control box (red plug unit if it matters at all. I'd prefer to go straight to the engine for wiring instead of taking my controls apart again. Thanks.

 

[F_R]

Never heard of a one-wire tach. No ground wire??? Anyhow, grey is the tachometer signal wire.

 

[craveman85]

Its got a ground that goes to the boat. I assumed it was the same as 3 wire without a backlight.

 

[F_R]

OK, a two-wire then. Not knowing if it is compatible or not, the answer still is the grey wire is tach signal. It comes from the alternator and counts the AC pulses. Needless to say if it isn't an alternator tach, it won't work

 

[craveman85]

Should I go from the actual power pack or that terminal strip on the motor

 

[craveman85]

Any idea what the pulse setting should be?

 

[F_R]

NOT the power pack. You will find the grey wire along with yellow ones on the terminal strip. I'm fairly sure it is 6 pulses.

 

[boobie]

What brand tach is it ??