Howdy,
You can easily wire a "kill switch in the circuit. It can be basically anywhere too........ you can put it in the engine compartment or under the dash.
The following diagram shows the wire where you can place the switch:
Just place the switch anyplace in the purple wire. Opening the switch will remove power from the ignition switch. The RED/PUR wire would also work too.
The purple wire is usually where the "kill-lanyard" switch is wired if your throttle quadrant is so equipped. (pretty good idea to have one of these to "kill" the engine if you fall out of the boat!)
If you just want to prevent the engine from cranking, you can place a SPST (single pole/single throw) switch in the YEL/RED wire (in series) .......... which is also used to prevent starting in gear. (neutral safety)
Cheers,
Rick
