Hi, my first problem was that the interior lights, fan and other items are not working with the battery power, but they are with the 120v power. I noticed, however, that the water pump IS working with battery power. (Solution found for second problem. It was the grounding.) THEN, as I was doing my pre-inspection, a bigger problem emerged. I am planning a trip tomorow, when I hooked up the camper to the electrical in the car, none of the exterior running lights are running. The way I have it hooked up, is I have an adapter to connect the 4 pin power conector in the car to the trailer's 7 way blade connector. And I have the ground wire from the adapter, connected to the frame of the car (Metal hook trunk latch). Last year, when I had another car, I had no issues. This is the first time hooking it up to my 2015 Subaru Outback. I don't know what's going on and I am concerned as I'm supposed to go camping tomorow with the family. Any help is appreciated.