Installing and Troubleshooting Curt C56351 T-Connector on 2016 Ford Fusion

Updated 11/20/2020 | Published 11/19/2020

Question:

i recently received and installed a Curt C56351 trailer wiring harness to replace my old defective one, my car is a 2016 Ford Fusion with PWM system, what ever that is. I hooked up the module and my turn signals/blinkers work just fine, but I don't have any running lights. I just put all brand new lights and wires from etrailer on my trailer. They seem to work fine as evidenced by plugging my trailer into my truck and neighbors van, and everything works fine, including running lights. Also, the Curt 56351 has an extra brown wire that the instructions don't say where to wire. I left it off and capped it. The graphics on the instructions clearly show the extra brown wire, but I couldn't find anywhere in the instructions what to do with it. This is suspicious because brown is supposed to be for the running lights. As a last piece of information, a test light on the extra brown wire never lights under any condition: running lights only, running+left turns, running+right turns, running+4-ways. Brown wire just appears dead, if its used at all. Please advise.

asked by: Gary B

Expert Reply:

Are you sure the extra wire you're speaking of isn't black? The Curt # C56351 will have two connectors that plug inline with the connection between the factory taillight harness and the taillight assembly. The one on the passenger side will have a green and white wire, the driver's side will have a white and a yellow wire. The converter box will also have two additional wires, one blunt cut black wire and one white wire with a ring terminal. The white wire grounds to the vehicle body, and the black wire is extended under the vehicle toward the engine compartment where it passes through the included fuse holder and attaches to the positive battery terminal. If this black wire isn't connected to the battery, you will not get full functionality from the wiring harness, and from your description it sounds like that's what happened.

You can see an installation video by clicking the provided link.

expert reply by: Mike L