I have a 2010 Fusion Hybrid that I am towing with a Bounder Class A motorhome. Even though I stop every couple of hours and run the engine, I find that sometimes the car will not start. The check engine light is on and the antitheft light is lit. The only way I can restart the vehicle is to jump it from another vehicle. I tow with the car in neutral, key in the accessory position, and parking brake in the off position as per the owner's manual. I am using a Brake Buddy which is plugged into the 12 volt outlet in the car. The motorhome is wired to the car through a six pin connector for all lights. Any thoughts on what might be causing it to lock up?