4-Pole and 5-Pole Wiring Connectors and 4-Pole to 5-Pole Adapter

Question:

I have a 5 pin factory tow package harness on my 97 chev truck. My boat trailer is a 5 pin. I have a hopkins 5 to 4 Tinch adaptor. But now I need the 5 pin to 5 pin T adaptor so I can plug in my factory harness and then Tinch off to the trailer 5pin to 5 pin. Cant find one. I like the clean factory installed look. So how do I utilize the factory installed tow package 5 pin harness to my 5 pin boat trailer?

asked by: Scott

Expert Reply:

If both your truck wiring and your boat trailer wiring are 5-pin flat type connectors such as those in part # HM47890 you should not need an adapter. If I misunderstand your question I am sorry. Maybe you'd care to send some photos?

You can actually connect a 5-flat vehicle connector to a 4-flat trailer connector without any adapters at all since the wiring pin assignments and functions on a 4-flat are the same as on a 5-flat except for the one additional circuit on the 5-flat. Typically this additional circuit is used to either power a surge coupler's electric reverse lockout feature using the vehicle reverse light signal or to provide power from a trailer brake controller for electric brakes if the trailer has a standard coupler. What are the functions for that extra circuit on the truck and trailer?

If you want to have the ability to wire in multiple connectors on the trailer at the same time you can do so by using a junction box like # 38656. This would enable wiring in both 4-pole and 5-pole trailer-side connectors like # A35W42B and # A40W5B using ring terminals # DW05737-1.

We do offer an adapter # 20036 that allows easy conversion of a 4-pole vehicle harness to a 5-pole for the trailer. This adapter has a blue wire for the extra circuit, either for the reverse light signal or for brake power.

You may care to check out the linked article on trailer wiring which shows how each connector type's circuits are arranged.