Can 4-Pole Wiring Carry Running Light Signals for Both Sides of Trailer

Question:

So do brown wires from both left and right lamp need to be connected

asked by: Lee

Expert Reply:

Yes, the running lights on both sides of a trailer need to be connected to the brown running light wire in standard 4-pole trailer wiring. This can be done by adding a jumper wire that runs from one side of the trailer to the other or you can just use a wishbone style 4-pole trailer-side harness like 35-foot # A35W42B or 20-foot # A20WB which have TWO separate running light wires that avoid the need to run the jumper wire from one side of the trailer to the other. One brown running light wire gets routed to the running light on each side of the trailer.

A detailed article on trailer wiring is linked for reference.

expert reply by: Adam R