Adding a 7-Way Trailer Wiring Harness to a 2008 Ford E-150 Van with Factory 4-Way
Question:
Hello, I have a 2008 ford E150 van with a factory 4-flat. The 4-flat plugs into a much larger connector in the frame rail that has more than 4 wires in it. Im wondering if you have a 7-round with harness that will plug into that factory harness in the frame rail.
asked by: Mitch S
Expert Reply:
We actually have an FAQ article that explains exactly what you need to do to add a 7-Way to a 2008 Ford E-series van with a factory 4-Way wiring harness. I have linked it for you. There is no simple plug-in harness that will work but installation of # 37185 is still very easy with only minimal splicing required.
Basically, under the van at that connector you mentioned that has more wires in it, you will splice in the wires from the 37185. It is a good idea to use a circuit tester like # PTW2993 if you need one to determine the functions of the wires in this connector. The 37185 black wire is 12-volt power, and the blue wire is for output to the trailer brakes. The white wire gets ground to the frame.
The last wire is normally for reverse lights and would connect to a reverse light wire. But if this is not needed you can just tape up the wire and stow it out of the way.

Products Referenced in This Question
Product Page this Question was Asked From
Adapter 4-Pole to 7-Pole and 4-Pole
- Trailer Wiring
- Wiring Adapters
- Multi-Function Adapter
- 4 Flat
- Plug and Lead
- 4 Flat
- 7 Round - Blade
- Hopkins
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