4 Wire Trailer Wiring Diagram Troubleshooting. From the thousands of pictures on the web regarding 4 wire trailer wiring diagram troubleshooting,. The minimum recommended gauge of a 4 core trailer wire is 18 awg for the turn lights, brake lights, and. Trailer Light Wiring Diagram 4 Wire Trailer Wiring Diagram from trailer-wiring-diagram.com Trailer troubleshooting basics […]