I was recently pulling my travel trailer home from the lake and had to stop at a Gas Station. While pulling out, the cord that plugs into the rear of truck was severed. I have fixed it, but now my travel trailer running lights only work when I manully turn on headlights in my truck. It is very possible that I am mistaken, but I thought I used to run the running lights on my travel trailer using my daytime running lights, but the RV store in town said that he was pretty sure that you had to manually turn on headlights to make trailer running lights work. Anyone know for sure????