Johnson Tachometer Connection

[roger]

I have a 1975 Jphnson 115HP V

I have a 1975 Jphnson 115HP V-4.
Where and how should I connect a tachometer?
One came with my boat but all the wires were cut off of it.

 

[sparky]

It runs of the alternator. Ye

It runs of the alternator. Yellow / grey stripe wire and a ground.

 

[joereeves]

"Roger.... I don't know wh

"Roger.... I don't know what tach you have but a OMC tach (usually) has four wires (Purple, Red, Black, Gray). Purple would lead to 12v that is hot only when the key is in the "ON" position. Red would lead to 12v only when the light switch is in the "ON" position. Black would go to ground.

Gray would connect to a gray wire that should be available either at the engine instrument cable under the dash, or in the control box.

At any rate, take the hood off and look at your engine. You'll see a terminal block there with wires attached to it. One of those wires will be gray which is the terminal you're looking for. If there is no gray wire at that terminal, use the Yellow Yellow/Gray wire for the tach gray wire connection.

Now, if you have the regular factory type control box, you'll notice that under the key switch assy, there is a small rubber type plug which is in fact a three (3) wire electrical connection. This is designed especially for the OMC type tach that has the plug in type connection. The electrical connections at that plug are: 12 volts when the key is on (Purple), Ground (Black), Tachometer pulse wire (Gray).

Hope this helps you somewhat.

Joe

"