4-Pole Wiring Harness for 2017 Ford F-350 to Power Accessory Items with Lights

Expert Reply:

It sounds like you have an accessory like the B&W Custom Headache Rack # BWPUCP7500WA that requires your F-350's lighting signals to operate. Items like lighted hitch covers, headache racks and other aftermarket items with lights such as mud flaps will require the lighting signals found on a 4-pole trailer wiring harness.

You can very easily add a second wiring harness to a truck with a factory 7-way by installing Curt 4-pole kit # C55384. This harness has two round U.S. Car type connectors that simply plug in inline with the factory wiring to give you a second active wiring harness for the lighting signals needed for your lighted accessory.

You can refer to the linked article on wiring for information on how the circuits are organized. In 4-pole wiring the brown wire is for tail lights, the yellow wire is for left stop/turn and the green wire is for right stop/turn. The white wire is ground.