12v/24v trolling motor wiring

[carpcatcher]

I just purchased a used boat with a minnkota trolling motor on it that can be switched back and forth between 12 and 24 volts. The previous owner has wires going everywhere and not hooked up to any batteries. There is three wires coming off the pedal, Red, White and black. I've never wired one that has had the third wire so I'm not sure what would go where. Does anyone have a "wiring for dummies" scamatic I could see?