Snapper Expert needed - Briggs ignition/charging

Preparing a couple of like new snapper riders for sale. Just don't use them anymore. They start and run great. Here is the problem on both. The Briggs engine has a wire coming from the magneto. Ground this wire out to metal and the engine stops. This wire also must be how the battery is charged. The magneto wire from the engine goes to a terminal screw on the side of the engine block. Also attaching to this terminal is a wire from the on/off switch and a wire going to an electrical wiring compartment. The on/off switch can be hooked to the magneto wire when the switch is on and the engine starts. Turn the switch off and the engine stops. The problem is the other wire. When it is hooked to the terminal the engines will not fire. Take it off and the engine starts right up. Looks to me like this particular wire hooks to some little plastic device in the area where the solenoid is housed. I assume this is somekind of regulator to charge the battery. Do these things short out and if it did would it ground out the magneto so the engine wouldn't start? Ever have this problem??? How is it fixed?? I just unhooked the wire and it starts and shuts off just fine, but I am sure it doesn't charge. How can the magneto make current for the ignition while not having the charging circuit ground it out??? Thank you.

Rather than worrying that is is a "Snapper", you need to focus on the engine (Briggs) model number. Pop the Briggs # into GOOGLE and you should be able to pull up a wiring diagram. There is a red wire and a white wire... one is "kill", and the other is a battery charging output. Depending upon the model number, there MAY be a diode involved in the wiring lead.