# Kill switch



## macawman (Jun 21, 2018)

Looking for suggestions for wiring kill switch functionality into a 1956 Johnson 10 hp o/b.


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## jethro (Jun 22, 2018)

I just had to learn the way the kill circuit works on my 25hp Merc. I'm guessing it would be the same for your motor. Basically you have a wire that comes from the flywheel/magneto and powers the coils. The kill switch is designed to ground that circuit out. So my kill switch (which is a tether switch) is broken when the tether is in place, and when you pull it the circuit then closes and creates a ground so the magneto spark goes to ground instead of generating the coils. Hopefully that helps.


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## macawman (Jun 22, 2018)

Thanks, Jethro. I was thinking something along that line, but it's great to know it has been tried and actually works.


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## Shaugh (Jun 22, 2018)

Old motors like that relied on the choke as the kill switch. It works instantly on my motors... Are you worried about a tether ?


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## macawman (Jun 22, 2018)

Yes, ultimately, to a tether is what I am concerned with. I will be fishing alone most of the time and the thought of a run away boat worries me.


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## Shaugh (Jun 22, 2018)

I've thought about doing it..... why not just loop a cord from your wrist to the choke knob.... what are the chances that you'd find a way out of that boat and not pull the choke out on the way ?


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## macawman (Jun 22, 2018)

That thought crossed my mind, but in my case, it would work only if I was tossed forward since that is the direction of action of the choke control. If I was tossed over the transom, I would just be dragged behind boat by the lanyard.


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## Shaugh (Jun 22, 2018)

You could run the cord through a loose zip tie around the tiller....


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## macawman (Jun 22, 2018)

Now, that's a thought.


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## jethro (Jun 26, 2018)

A kill switch tether should be less than $10 at your local marina or on Amazon and wiring it like I said is incredibly easy. I would go that route rather than risk wrecking your choke knob, which sounds to me like a bad idea anyway. What if the reason you get tossed from the boat is because you hit something, which could possibly cause an air leak in the intake? Then you choke it and it takes off like a scalded cat! The tether is the way to go.


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