Why would the 12v outlet and USB plug (both DC power) only work when the trailer is plugged into an AC power source? That doesn't make sense. You would think that they would be supplied by the 12v system....
Be Safe, and Everyone Goes a Home,
2014 RAM Laramie 2500 w/6.7L Cummins Diesel and Automated Safety Hitch
2016 377RLBH Jayco North Point
300W of Suntech Solar w/Rogue MPPT Controller & Xantrex 2000W PSW Inverter