It sounds like your truck has a 4-way flat trailer connector with yellow, green, brown and white wires (see picture), which is pretty standard. It also sounds like your trailer has 5 loose wires that you are trying to connect to a trailer side 4-way flat connector similar to part # W787264.
If this is the case, then it sounds like your trailer came with a wishbone style wiring harness meaning you have two running light wires (brown wires) for each side of the trailer, the left turn signal... view full answer...