Wiring question.

I did actually have my lights turned to Auto when I checked those terminals, I had forgotten to turn them to On because I never use the On setting. One strange thing about this is I hooked the trailer umbilical back up after checking the truck terminals and the left trailer blinker and left trailer brake light started working. I also do not have a battery on the trailer at all yet. I thought the trailer lights always took power from the truck. I do have a deep cycle i can use on it temporarily. I planned on buying a new battery for the trailer since it didn't come with one and the one I do have is quite old, not sure how much life is left in it.