Strictly speaking, it doesn't matter what kind of charging system (magneto or alternator) you have. It's all about how the kill switch prevents spark. I thankfully haven't had a reason to dig into that circuit on my PCM EX343 engine, but on the Mercury engine in my former jetboat the normally open switch was wired to all six CDI modules that drove the spark plugs. When the lanyard was removed, the switch closed and grounded that CDI connection, instantly killing spark on all cylinders. That was as direct a kill circuit as possible because it bypassed everything... no matter what anyone or anything else (such as the ECU) said, that engine wasn't going to run anymore.
That same CDI control line was tied into by a few other safety systems on the boat including one of the two rev limiters, the keyswitch, and the throttle lever's neutral switch. It is a very convenient way to handle the "engine kill" action because all you have to do is ground one wire.
I strongly suspect your engine has this same type of kill circuit because of its simplicity and reliability - both key advantages in anything safety related. What you did by rewiring the switch was go from the normally closed terminals (open when the lanyard is on, so the spark circuit isn't grounded and the engine is allowed to run) to the normally open terminals (open when the lanyard is OFF). If you're curious, try disconnecting one or both wires. If the engine will start and run, it's as I've described above. If it won't, then the switch is being used in some sort of circuit-completion approach.
(Note that the circuit-completion approach would be even safer than the way my Mercury worked because it would alert the operator to a failed or disconnected kill switch. Anything that relies on an open circuit to run will silently tolerate a failed or disconnected switch, not a good thing for a safety feature. But it isn't as inherently simple to configure a closed-to-run system, so I bet we're still looking at simple ground-to-kill circuits.)
That same CDI control line was tied into by a few other safety systems on the boat including one of the two rev limiters, the keyswitch, and the throttle lever's neutral switch. It is a very convenient way to handle the "engine kill" action because all you have to do is ground one wire.
I strongly suspect your engine has this same type of kill circuit because of its simplicity and reliability - both key advantages in anything safety related. What you did by rewiring the switch was go from the normally closed terminals (open when the lanyard is on, so the spark circuit isn't grounded and the engine is allowed to run) to the normally open terminals (open when the lanyard is OFF). If you're curious, try disconnecting one or both wires. If the engine will start and run, it's as I've described above. If it won't, then the switch is being used in some sort of circuit-completion approach.
(Note that the circuit-completion approach would be even safer than the way my Mercury worked because it would alert the operator to a failed or disconnected kill switch. Anything that relies on an open circuit to run will silently tolerate a failed or disconnected switch, not a good thing for a safety feature. But it isn't as inherently simple to configure a closed-to-run system, so I bet we're still looking at simple ground-to-kill circuits.)
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