Hello first time post. found a 2007 Troy bilt zero turn push mower with a sweet Kawasaki engine on it in the trash, the machine required basic fixes and fired up first shot, I noticed it had a key start that was missing when I found it. I’d like to make my own key start for this mower, I found 3 wires coming from the starter, 1 of the wires confuses me to its function it’s a thin black wire that runs up to a copper winding attached to the ignition coil. What is it’s purpose? Kill switch for the key? Battery charger? Time Machine? Thanks.