How to add killswitch 20hp mercury ?

mc66

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May 18, 2010
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I have a 1978 20hp mercury with controls. Does anyone know where or what wires to connect a universal killswitch. I have wiring diagrams and one seadog killswitch.I would like to hook it up to controls but dont know what to do with switch. If i go to motor i will need more wire, more wire more problems. Seadogs websight has no information. Switch has none either it only shows ignition or magneto connections .thanks
 

Fireman431

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Re: How to add killswitch 20hp mercury ?

If you are running thru the ignition connections, I believe you can just run the ignition wire from the key switch to the kill switch, then out to the ignition. Basically just put the kill switch in line. That would be for a normally closed circuit connection and when the lanyard is pulled, it opens the circuit (essentially turning the key off).
 

NYBo

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Re: How to add killswitch 20hp mercury ?

I think you have it backwards, Fireman. That motor should have a magneto system, so the OP has to use the magneto terminals on the killswitch, which are normally open. Pulling the lanyard shorts to ground, just like turning off the ignition switch.
 

Fireman431

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Re: How to add killswitch 20hp mercury ?

I think you have it backwards, Fireman. That motor should have a magneto system, so the OP has to use the magneto terminals on the killswitch, which are normally open. Pulling the lanyard shorts to ground, just like turning off the ignition switch.

I totally missed which engine he had. Thank you.

On the other hand, I did say if he went thru the ignition connections, then it was a normally closed circuit...:)
 

mc66

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Re: How to add killswitch 20hp mercury ?

So if i understand you guys correctly i would connect the killswitch to the black wire on my ignition switch.According to my diagram black goes to ground. Connecting the two prongs that are marked magneto does this sound correct.
 

mc66

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Re: How to add killswitch 20hp mercury ?

Here you go, Bubba 1235. thanks
 

mc66

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Re: How to add killswitch 20hp mercury ?

Thanks i"ll give it a shot. I must cut wire all connections to ignition soldered together
 

mc66

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Re: How to add killswitch 20hp mercury ?

Disconnected red wire still runs now what ?I dont know but i cut loose the other end of wire at rectifier does this matter.Red wire is off engine still fires up Forget it diagram a little different going to cut in like you suggest.Red to ignition constant hot no heat no fire i hope will post back when i know
 

NYBo

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Re: How to add killswitch 20hp mercury ?

No, no, no! Don't mess with the red wire. You need to hook the kill switch across the two magneto leads, with the switch shorting them when the lanyard is pulled. But I can't tell which two wires that would be; your diagram is a bit confusing. What color wires do you have attached to your ignition switch, and what are the corresponding terminals labelled?
 

NYBo

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Re: How to add killswitch 20hp mercury ?

Here's a way to figure out which wires to use:
Determine which two terminals on the ignition switch show continuity when the switch is OFF and an open circuit when the switch is in the RUN position. Attach the kill switch across these terminals, being sure to use the terminals labelled "magneto" on the kill switch. That should do it.
 

mc66

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Re: How to add killswitch 20hp mercury ?

Thanks I just did that before i read your post just being lazy.Orange wire and black when switch off there is continuty. (grounding ignition) Key in run position no continuity.Taped into each wire soldered together and we have a working kill switch. Thanks again to all who replyed mc66




Remember what Chuck Taylor said Stay True
 
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Feb 27, 2014
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Guys,
Sorry to hijack an old thread, but I seem to be having the exact same problem. My switch as per the picture, has continuenty when the swith is off but also when in run and start.This is between the orange and black.....
Is my ignition switch the wrong type?
 

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NYBo

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Michael: Thats a terminal block, not the ignition switch so it doesn't help at all. Start your own thread with a picture of the switch, as well as giving some info about the motor.
 
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