wiring diagram for OMC tach

[beach]

I have an old (60's) boat with an OMC tach. The wires look like; white, black, blue, purple. I am running a 40 hp 69 johnson and the book says the harness has a tach lead, I just need to know where all the wires go.

 

[wraenking]

Re: wiring diagram for OMC tach

im pretty sure you want the purple wire for your tach, but i would wait for others to confirm.

 

[imported_JD__]

Re: wiring diagram for OMC tach

beach,<br />Black is your ground connect to terminal marked "GND"<br />Purple wire is your accessory or hot wire, usually comes off the ignition switch, connect to terminal marked "+12V". If your tach illuminates, you may need to make a short jumper from the +12v terminal to the light bulb terminal, depending on your tach.<br />White/gray is usually the tach wire from the engine. Connect to the "Pul" or pulse terminal.<br />JD

 

[rickdb1boat]

Re: wiring diagram for OMC tach

Your sender wire will have 5-7 Volts coming off it with the key in the on position. Check the purple wire for 12 Volts. Check the blue wire and see what you get.( It may also be 12 Volts) Of course, black will be your ground wire. All of this is done with an voltmeter, and with the key swich in the ON(Not Start) position. I'm guessing the white will be the sender wire.

 

[beach]

Re: wiring diagram for OMC tach

What is the pul terminal?

 

[imported_JD__]

Re: wiring diagram for OMC tach

beach,<br />Pul is the abbreviation for pulse, electrical pulses from your engine/alternator.

 

[beach]

Re: wiring diagram for OMC tach

The motor is a 40hp johnson 1964. It has 2 magneto coils. Where do I hook up the tack white wire in relation to the motors wiring?

 

[Paul Moir]

Re: wiring diagram for OMC tach

Beach, if that is a tach for non-magneto applications (post mid 70's johnny/rudes) then it will not work. It will only work with stator equipped outboards. The pulse from them is completely different than the pulse from a magneto powered outboard. In fact, the number of pulses per revolution are different too.<br /><br />If, however, it is ment for your 40hp then you connect it to one of the two magneto 'kill' wires. They ought to be black and connect to the 'M' terminals on the keyswitch.

 

[beach]

Re: wiring diagram for OMC tach

How can I tell if the tach is the proper type? If I hook it to a kill wire and is was not the right tach can it cause damage to the coils.