What do these three wires do?

[kciv]

I have a three wires coming out of the bottom of the control box. I have a 1978 70HP Johnson with control box that came from who knows what? They are black, gray, and purple. What are they for? I am in the process of putting this outboard on an old boat and wiring it up from scratch.

 

[Joe Reeves]

Re: What do these three wires do?

Tachometer leads.

Black = Ground
Gray = Sensor
Purple = 12v power

 

[kciv]

Re: What do these three wires do?

Thanks Joe. I did not read the first line.

 

[wilde1j]

Re: What do these three wires do?

Tach signal=grey, switched hot=internal illumination for tach, black=ground for tach

You don't power anything, just hook the leads up to the tach.

 

[Joe Reeves]

Re: What do these three wires do?

I do not understand the meaning of your statement that reads....... "I did not read the first line."

 

[wilde1j]

Re: What do these three wires do?

Joe, I think he meant: "Tachometer leads."

 

[kciv]

Re: What do these three wires do?

Joe -- I did not see the first line in your post that told me what each lead did.

Can I use this tach? How do I hook this tach up? The tach part number is OMC291274. What does the plug that goes in the socket look like. Does anyone have pictures? Web site that I can look up this part number?

 

[Joe Reeves]

Re: What do these three wires do?

The socket..... If you're spaeking of the hole in the back of the tach, my guess is that a light bulb goes in there. Exactly what kind of bulb socket.

I can't make out what the back of that tach looks like. A hint in picture taking is to have the area well lighted, and kill the flash feature on the camera. This will give a clearer picture (works for me anyhow).

But, at any rate, let us know what connections exist on the back of that tach, how many, what are they marked?

Should they be marked something like "G" or "GND" (ground), this would be the black wire connection.

A connection marked "S" or "SEN" (sensor), this would be the gray wire connection.

A connection marked "+", or "POS", or "BAT" or "12v" would be the purple wire connection.

If a dial exists on the back of the tach, try setting it on #6.

Let us know what you find.

 

[Bifflefan]

Re: What do these three wires do?

The hole is for a light. You can get one off an old set of gauges from a flea market or something. The one your looking for has metal fingers that are curved and fit in the hole and hold an old style light bulb like older tail lihgt bulbs but smaller. If you lived by me i could give you one.

 

[kciv]

Re: What do these three wires do?

If the socket is for a bulb, then I have only two connectors. There are no markings on the two shovel connectors or the socket. The body maybe the ground. Positive ground or negative ground?

Do you have a picture of the bulb? The socket is a slide on type and does not have a place for the two nubs of a light bulb. Is the old type light bulb that you are talking about a type that does not twist to lock? The old type bulbs that I a familiar with go on old cars and pop in the back of the gauge housing. This socket is not that type.