How to Wire a 4-Way Hitch to a 7-Way Trailerby K.K. Lowell
Wiring a 4-way hitch plug to a 7-way trailer is not a difficult thing to do, but, it will not power all the circuits that are connected when the trailer is plugged in to a vehicle with a 7-pole connector. For long-term use, the connector on the vehicle should be replaced with a properly wired 7-pole connector; but for short-term use, such as transporting a newly acquired trailer, these connections are not difficult. Adapters are available to do exactly what this wiring does, but at much greater cost. So why not make your own?
Connect the white wire from the male 4-way trailer plug to the ground terminal of the 7-way receptacle.
Connect the brown wire from the 4-way plug to the running lights terminal of the 7-way receptacle.
Connect the yellow wire from the 4-way plug to the left turn signal terminal of the 7-way plug.
Connect the green wire from the 4-way plug to the right turn signal terminal of the 7-way plug.
Mount the 7-way receptacle to the underside of the tow vehicle bumper using self-tapping screws. Simply plug the 7-way from the trailer into the 7-way receptacle and the 4-way connector into the 4-way on the tow vehicle to use.
- The electric brakes on a trailer will not be powered with this setup. You must allow adequate stopping distances to account for this. Accordingly, never haul a heavy trailer when connected in this manner. The breakaway brake will still function as normal, provided the on-trailer battery is charged and the breakaway cable is connected to the tow vehicle.