Replacing the 7-Way/4-Pole Trailer Connector on 2010 F-350 Super Duty-King Ranch
Question:
I am looking for guidance on replacing the tow package wiring harness on my 2010 F-350 King Ranch Dually. When connected I have no running lights and Ive checked the fuses and they all seem to be intact. I did a light test on my 7-pin and I have no power except at the 12 oclock pin. I cant find any videos on YouTube or any information on a Google search to complete this repair. I also need help ing the correct wiring harness for that make and model vehicle.
asked by: Keith
Expert Reply:
Your F350 should have come with the factory tow package. You'll need to figure out if the connector you currently have is damaged, or if the problem might be further down the line. Follow the wiring for the existing trailer connector until you find the round US car connector. Unplug that connection. On the vehicle side of the connection, use a circuit tester like part # PTW2993 on the connector as a helper activates each taillight function. If you're getting signal for the running lamp, right and left turn and brake lamps, you've confirmed that the existing trailer connector is faulty and should be replaced. The # HM40975 would work great, it's the connector that Ford, Chevy and Ram are currently using as the OEM trailer connector. The US car connector will plug directly into the rear of the # HM40975.
If you aren't getting power on the running lamp circuit at the connector, check the 30 amp fuse in the # 42 location and the relay in the # 55 location in the power distribution box under the hood. Replace the fuse if it's blown. You can't tell by sight if a relay is bad, but you can swap it out for an adjacent relay, and see if that fixes the problem.
Getting the connector functional is only half the battle. If there's a blown fuse or a bad relay, chances are that there's a short in the trailer wiring that caused the fuse to blow. Since the problem centered on the running light circuit, that's where you'll want to check. Beginning at the trailer connector, trace the running light circuit (usually a brown wire) from the connector back to the trailer lamps. Look for pinched wires, loose connections or cracked or worn wire insulation that would allow the circuit to short out on the trailer frame. Repair the short as needed.
I'll link you to our trailer wiring and trailer wiring troubleshooting FAQ articles, which I hope you'll find helpful.
Products Referenced in This Question
7- and 4-Pole Trailer Connector Socket w/ Mounting Bracket - Vehicle End
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- No Converter
- Custom Fit
- 7 Round - Blade
- 4 Flat
- Hopkins
more information >
Product Page this Question was Asked From
7- and 4-Pole Trailer Connector Socket w/ Mounting Bracket - Vehicle End
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- No Converter
- Custom Fit
- 7 Round - Blade
- 4 Flat
- Hopkins
more information >
Featured Help Information
Instructions
Miscellaneous Media
Continue Researching
- Shop: Trailer Wiring
- Search Results: oem 7 pin connector ford
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Shop: EZ Connector Magnetic 7-Way Trailer Connector with 8' Long Cable - Watertight Seal - Trailer End
- Article: Testing Trailer Brake Magnets for Proper Function
- Shop: Reese Multi-Plug Wiring Harness for Factory Tow Package - 7-Way and 4-Way Flat Trailer Connectors
- Video: Performance Tool Hook Probe Circuit Tester Review
- Search Results: trailer hitch wiring
- Video: Choosing the Right Trailer Wiring
- Shop: 7- and 4-Pole Trailer Connector Socket w/ Mounting Bracket - Vehicle End
- Shop: Trailer Hitch
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Article: Trailer Wiring Diagrams
- Video: Tow Ready 4-Pole Mounting Bracket Installation
- Shop: Suspension Enhancement
- Search Results: trailer hitch
- Q&A: What is the Difference Between a 4-Way and 7-Way Trailer Connector
- Shop: Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires
- Video: Choosing the Right Brake Controller
- Article: How to Choose the Right Trailer Hitch Class
- Shop: Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector
- Search Results: etbc7
- Q&A: 7-Way Trailer Plug Adapter or Compatibility with Lance Slide-In Truck Bed Camper
- Shop: Brake Controller
- Video: Choosing the Best Fifth Wheel Hitch
- Shop: Tekonsha Prodigy P3 Trailer Brake Controller - 1 to 4 Axles - Proportional
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Search Results: hitch
- Q&A: What Is An OEM Prep Package And How Do I Know If I Have It
- Video: Curt 4-Pole Flat Trailer Connector Mounting Bracket Review