Well,,,, I don't know about that...
I have decided that the switch is for turning off the speed control.
This after Rick keeps telling me that is what it is for...and me telling him that the wiring diagram for the speed control does NOT GO THERE... it goes to the brake switch light circuit.
But when thinking about it... I think it is connected to the clutch pedal to keep from overspeeding the engine by disconnecting the speed control when the load is removed from the engine.
I had gone out and tried to start my car ... will start in neutral and in ANY GEAR with me standing outside the car turning the key... Don't try that at home.... or at least not with the car Pointed at your home....