WIRE DIAGRAM FOR 6 PIN TRAILER CONNECTOR
Trailer Wiring Diagram For 4 Way, 5 Way, 6 Way and 7 Way
6 Way System, Rectangle Plug. 3/4 inch by 1 inch 6 way rectangle connectors right turn signal (green), left turn signal (yellow), taillight (brown), ground (white). The red and blue wire can be used for brake control or auxiliary. Use on a small motorcycle trailer, snowmobile trailer or utility trailer.
Trailer connectors in North America - Wikipedia
If you have a trailer with a lot of lights the diode and relay wiring is preferred, but if you have a trailer with a simple light arrangement it is usually sufficient to wire to 58L. In market there are many special converters    that solves the problem of connecting a car with European wiring to a trailer with North American wiring.
Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector Tow
The Adapter 4 Pole to 7 Pole Vehicle End Trailer Connector part # 30717 can be used to adapt the 4-pin connector on your vehicle o the 7-way on the trailer side. You simply ground the 7-way plug and plug the 4-pin into the pigtail from the plug.
Trailer Wiring Junction Box - 7 Color Coded Terminals
I've attached a trailer wiring diagram to assist. In regards to the 7-Way Molded Trailer Wire Connector part # H20043, the yellow wire is for the reverse light circuit yes. This should then align with the pin responsible for the reverse light circuit on your vehicle. The terminology used for "AUX" is the same as the reverse light circuit.
How to Rewire a Trailer in 8 Simple Steps
Rewiring a trailer involves removing the old wiring and trailer lights, routing the new wiring harness through the trailer frame, installing new trailer lights and testing the lights. This guide walks through the steps required for how to rewire trailer lights. It can be used