Troubleshooting 7-Way Socket on 2006 F-150 Used with 7-Way-to-4-Pole Adapter

Updated 05/12/2017 | Published 05/11/2017

Question:

I purchased an 7 prong round to a 4 prong flat adapter and new lights and running lights and wiring the wire colors are white,brown,yellow,green. I know yellow and brown go to one side and green and brown go to the other does the brown wire from the right have to attach to the brown on the left. My running lights are not working also. How do I get this worked out.

asked by: Dewayne B

Expert Reply:

It is best to first test the 7-way on your F-150 without the 7-to-4 adapter plugged in. You will need a circuit tester like # PTW2993 to test the pin for each lighting circuit on the 7-way. Please refer to the photo I linked for you that shows what signals are to be found on each pin of a 7-way vehicle socket like # 37185. Testing this first lets you know the right signals are there for the adapter.

In a 7-way type socket the running light signal for both sides of the trailer is carried on the pin at the 11-o-clock position. A 7-to-4 wiring adapter will route that running light signal to the brown wire that connects to the pin that is next to the ground. If you have 4-pole wiring that uses two brown wires, one for each side of the trailer, this is called a wishbone harness. It should NOT be necessary to splice the two brown running light wires together; each one should carry the same signal.

If you need additional help please feel free to tell me the brand and part number of your adapter. You can also refer to the linked help articles on wiring.

expert reply by: Adam R