Emergency cut off

[tbeaze24]

I have a 96 Johnson 225, and it did not have the emergency cut off on it. I bought the kill switch and it says cut the black and yellow wire, I put the kill switch in between and it did nothing?? I need some help. Thanks, Tim

 

[Chris1956]

Re: Emergency cut off

Tim, Johnny's of that era have the emergency cut off function integrated into the ignition switch. You clip a lanyard to the ignition switch and when you pull te lanyard, the key is physically turned off. You might see if you have this feature.

Secondarily, the cut off feature works by grounding the black/yellow wire. You want to connect the black/yellow wire to the cut off switch, and then to the ignition switch. Now connect a ground wire to the cut off switch.

 

[tbeaze24]

Re: Emergency cut off

Yes, It still had the sticker around the ignition switch showing it how to hook the lanyard, but previous owner replaced switch with regular push to choke, no cut off type switch. I am still not sure about the wiring. I know about the black/yellow wire, but the cut off switch has four blade connectors, 2 with c and 2 with m, directions say for outboards to use the c. How do I keep the black/yellow hooked up on the key switch, have the wire cut, going thru the cut off and to ground? What ground do I use? Any help would be greatly appreciated. Thanks, Tim

 

[jtexas]

Re: Emergency cut off

beaze,
You need a normally open switch, let's assume "c" is right since that's what your instructions say. Or confirm it with a continuity tester.

Now, you want to tap into the black/yellow wire - use a butt connector to reconnect where you cut it, but on one end of the connector, add a jumper wire - two wires in one end, one in the other.

On one C terminal, connect your jumper wire. On the other, connect another jumper wire leading to any good ground. Either to a negative buss bar, the (-) terminal of the battery, or tap into any other ground wire.

When you trip the switch, it closes, grounding out the ignition.

 

[Silvertip]

Re: Emergency cut off

I think your kill switch is dual purpose in that it can be used for magneto (M) ignitions (as in an outboard) or coil (C) ignitions as in an I/O or inboard. I'm wondering if the instructions are wrong. Magneto ignitions require grounding the M lead on the ignition switch to kill the ignition. On a coil ignition system its the opposite -- the circuit must be closed to energize the ignition and open to kill it. Use an ohm meter across the C terminals and again across the M terminals. If you have continuity across the M terminals with the system inactive (as thought the lanyard was pulled) those are the correct terminals to use. If you have continuity across the M terminals with the clip in place, those are NOT the terminals to use.

 

[tbeaze24]

Re: Emergency cut off

Don't think I am stupid guys, I am an avionics tech on 24 million dollar helicopters, but this has got me stumped. It is an Attwood cut off, and I swear I may have tunnel vision here, but I do know it is a dual purpose i/o or out board, but the directions for the outboard on say find the black/yellow, and ground it out. It is a magneto, and the schematics just say, but the switch in the middle of the black/yellow and take it to ground. I didn't want to mess anything up,and I thought about putting the 2 wires in a butt connector, but was not sure if I would mess something up. I disconnected every wire on the key switch and none of them cut it off, so I was a little bewildered. I did this same thing with an i/o last year, and it worked fine right off the bat. Thanks guys, Tim

 

[Chris1956]

Re: Emergency cut off

Tim, The black/yellow wire needs to be grounded to stop the motor. Put a continuity meter on the cut off switch. Check all combinations until you fin one the has continuity (zero resistance) when the switch is tripped. Connect the black/yellow to one of the chosen connections, and also run it back to the ign switch. Now connect ground to the other connection, and run the ground wire back to the ignition switch.


On an outboard of this vintage, pulling all the wires off the ignition switch, with the engine running will not kill it. Grounding the black/yellow wire will kill it.

 

[jtexas]

Re: Emergency cut off

...the switch in the middle of the black/yellow and take it to ground. ...

that's it exactly. Except the switch doesn't interrupt the black/yellow.

A little theory might help:
The kill wire (black/yellow) is connected to the capacitor output from the "capacitor discharge ignition", parallel with the powerpack. For normal operation the kill wire is Not Connected. When grounded, it drains the capacitor, short-circuiting the ignition, no spark, engine dies.

Keyswitch in the "off" position connects kill wire to ground. Your kill switch will be in parallel with the keyswitch, normally open, closed when tripped.

 

[Silvertip]

Re: Emergency cut off

Outboard (two stroke) ignitions must be grounded to kill the engine. Your first job is to identify the two terminals on the kill switch that are closed when the lanyard is pulled. Those are the terminals you need to use regardless what the instructions say.

Then check the back of the ignition switch. You should find an "M" terminal and an "I" terminal (or two "M" terminals). When the key is turned off, those two terminals are shorted to kill the engine. Therefore, connect the kill switch across those two terminals. When the lanyard is pulled, you kill the engine in the same manner as turning off the key.