I can't get a vehicle to work properly; it moves on it's own?

I am working on creating a train kind of idea, and the motors are set not to move, but are moving regardless. I'm thinking a script might be needed, but I can't figure out where to begin, as this could be a number of issues. From my experimenting, I do know that setting the side parameters to what should be disabled, it just continues to rotate even without an occupant In the VehicleSeat. Any ideas what I should do to fix this?