Is the Center Pin Reverse or Accessory When Wiring Horse Trailer 7-Way

Question:

We have to replace the 7 prong plug on a horse trailer. The trailer wiring diagram gives the wire colors, functions and placements in the plug. The new plug has different color wires so we will use the functions. The placements of the wires on the pictures do not match between the trailer code and the new plug. For instance the center of the trailer’s plug says accessory auxiliary. The center on the new plug says reverse lights. The trailer has a black wire at 11oclock that says battery hot charge. There is nothing similar listed on the new plug diagram. Seems like we could damage something with these inconsistencies. How can we tell what the truck will recognize correctly? Thanks

asked by: Linda H

Expert Reply:

If you have a factory seven way trailer connector on the tow vehicle then it will be wired as either traditional or standard which means the center pin is for reverse and the one o'clock is for battery charge. I have attached a chart below. That said, you can test which pins are where on the truck before you wire the trailer plug. I recommend the etrailer Trailer Wiring 7-Way Upgrade Kit part # HS381-9000. You are right in that you must match wires by function, not color on the trailer when replacing the plug.

expert reply by: Conner L