Originally Posted by Daubsy
The previous owners of my trailer added halogen lights below the rear bumper. I'm pretty sure they used it as fog lights, as it had a separate two pin connector for the tug. Since I had no way of hooking it up to my truck, I just tied it into the auxiliary output on the trailer pigtail for backup lights.
They might not have had the auxiliary pin connected to anything in their tug, and just manually plugged in these lamps in preparation for backing up. You normally get out anyway to take a good look before starting to back into a campsite.
If those lamps are white, or even yellow, I certainly hope they were not
driving down the road with these lamps on. Conditions are rarely appropriate for rear fog lamps, and even when they are those lamps are red.