While I wish I could tell you exactly what color wire goes to each function there is no standard wiring guide required to be used for trailer manufacturers and the manufacturers of the wiring/lights. Looking at the wiring you do have I see the trailer has white, red, and green on the left side with white brown and green on the right. It would most likely be safe to assume the red and brown wires operate the turn signals and brake lights for each side of the trailer. The green is most likely... view full answer...