I have a 1983 9.9 Evinrude that I want to install a Emergency shut off switch, the one that if you go overboard the engine will shut off. I have purchased the switch, it has two wires, one for ground and the other goes to where? Bench testing the switch, with the device to keep the button extended nothing on the multimeter, with the device removed and the button in the in position I have continuity. Is this correct to shut down the motor?