Mercury 4 cylinder 2 stroke Tach take off?

[James R]

Cant give you a year but I can say that it is OA-0D 100 HP with the clam shell. The only number I can see is on a welch plug.
B373047.
The schematics I have do not show the connection at the motor for the tach. Can anyone help me on this?
Thanks.
Jim.

 

[sly_karma]

Instrument wiring comes from a short pigtail cable coming from the operator controls. Usually it's a 5-pin Amphenol plug. You need a compatible Merc instrument wiring harness with matching plug to run to the dash. The wiring from the controls is as follows for most Mercs:
Black: ground
Purple: +12V via ignition switch
Grey: tach signal
Brown-white: trim position sender
Tan: temp gauge signal
There might also be a low oil alarm wire in there which can be connected to a warning light in the dash for visual warning in case horn can't be heard over engine/wind noise.

 

[Chris1956]

Clam shell cowling usually means mid-eighties motor. Depending on what control you have determines what plug you need, to run tachometer.

 

[Chris1956]

Make that late 80's motor.

 

[Faztbullet]

Has to be a 1989 a 1st year 4 cylinder

 

[James R]

Great information guys,helps a bunch.
Many thanks.

 

[James R]

This rig has the 3000 control so the connection must be under the dash.
I can trace it with the colors.
Thanks again.