Small Engines (Lawn Mowers, etc.): Charging system wiring for craftsman rider, small engine mechanic, hp briggs

Question
I'm a small engine mechanic in Tx. and have a Craftsman Rider with a 16.5 hp Briggs OHV engine in my bay. Well it's a home owners machine and he had it stored in a barn ovr the winter and rats ate through the wiring harness on the right side between the engine and battery. I replaced the wiring harness but this engine has a small black regulator for the charging system mounted on the block behind the starter with 3 wires (red, black, and yellow) now I've connected the red and black but we're not positive the charging system is working. With a Volt/Ohm meter the yellow wire carries a .50 volt chargewhen the engine is running but the wiring diagram I found doesnt show where to connect it. Any ideas? I've tried all available wires on new harness not already connected but can find no change on battery charging test with meter. Need Help! Thanx

Answer
 Hello DW:

 If Memory serves me correctly; the yellow wire is connected to the Ignition Switch. Has power ONLY when Switch is On. The Box is a Voltage Reg. This is really the Old Style Charging System. The Newer one have the Regulator Built in. To check the Charging System: 1- Start the Engine. Take the Ground Wire Off and Hook a DC (at least to 24V) between the Cable and the Battery Post. It should Read between 13.5 VDC and 15 VDC. Hope this Helps.

 Good Luck

 Respectfully

 John