Trailer Lights Do Not Work When Connected to 7-Way Connector on 2013 Ford F-350

Question:

Trailer signals and running lights on trailer do not work. I have tested the 4 pin and they work but not at the 7 pin nor at the 7 pin located in the bed of the truck. Please help!

asked by: Jerry

Expert Reply:

If you are using the part you referenced, Hopkins OEM Style 7-Way and 4-Way Trailer Connectors for Ford # 30955, and the 4-way works but the 7-way does not, the first thing to check is that the round connector that plugs into the back of the 7-way is fully seated and that the locking tabs are engaged. Since the 4-pole has lighting signals we know the vehicle wiring is sending the appropriate signal to the round U.S. car connector that plugs in to the OEM harness. This makes the plug-in connection at the back of the 7-way the most likely suspect.

You can check that there are no signs of corrosion on the contact surfaces. Even very slight greenish or whitish discoloration on the contacts can indicate corrosion that can inhibit signal transfer. Clean the contacts as needed and apply dielectric grease, such as # 11755 to help prevent entry of moisture and dirt.

expert reply by: Adam R