Troubleshooting No Running Lights When Hooked Up to U-Haul Trailer
Updated 08/20/2025 | Published 12/01/2018
Question:
Uhual trailer I have a uhual hitch installed, the break lights and turning signals work but I was unable to rent the trailer due to the lights that turn on, on the side of the trailer for night time driving.
asked by: Felix P
Expert Reply:
If the running lights on the U-Haul trailer were not working when hooked up to your vehicle, then I first recommend testing the 4-Way or 7-Way (whichever you have) and testing the pins with a circuit tester like # PTW2993. Have somebody run through the lighting functions on the vehicle while you test the pins. If you don't get any power to any of the pins with the running lights activated, then you at least know the issue is somewhere on the vehicle and not on the trailer you hooked up to.
Inspect the connector itself for any debris or corrosion that needs to be cleaned out. Take a look at the wiring at the back of the connector for any exposed or pinched areas that need to be replaced. Also make sure the main harness ground is securely attached to a clean bare metal surface.
If everything looks good, I recommend checking your vehicle's owner's manual for the fuse locations to see if there is one for trailer running lights. If so, make sure this fuse is present and in good condition.
If you are still having issues, please let me know and we can continue to troubleshoot. I have also attached a trailer wiring troubleshooting article that you might find helpful.
Featured Help Information
Miscellaneous Media
Continue Researching
- Search Results: chrysler pacifica
- Shop: Trailer Wiring
- Search Results: trailer hitch
- Search Results: trailer lights
- Shop: Vehicle Tow Bar Wiring
- Shop: Trailer Hitch
- Shop: Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Shop: Curt Trailer Hitch Receiver - Custom Fit - Class III - 2"
- Shop: etrailer Trailer Hitch Receiver - Custom Fit - Matte Black Finish - Class III - 2"
- Shop: Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Video: Curt T-Connector Vehicle Wiring Harness Installation - 2022 Chrysler Pacifica
- Shop: Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Q&A: Will My Trailer Wiring Switch Over From My 2018 Chrysler Pacifica to My 2022 Pacifica?
- Shop: Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Shop: Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector
- Q&A: Trailer Running Lights Do Not Work but Brake Lights and Turn Signals Do Work
- Q&A: Running Lights Not Working on Trailer With New Wiring
- Q&A: Troubleshooting Trailer Wiring Running Light Circuit Not Active Curt Harness 2022 Chrysler Pacifica
- Q&A: How to Test Trailer Wiring Converter Box
- Q&A: How To Install The Peterson Square Trailer Tail Light Part # 432400
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Video: An In-Depth Look at the Roadmaster Battery Charge Line Kit for Towed Vehicles
- Article: Trailer Wiring Diagrams
- Search Results: trailer wiring
- Video: An In-Depth Look at the Roadmaster Diode 7-Wire to 6-Wire Flexo-Coil Wiring Kit
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Video: Curt T-Connector Vehicle Wiring Harness Review C56040
- Shop: Suspension Enhancement
- Search Results: trailer tires and wheels
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
on Trailer Wiring
Joe
8/19/2025
I try all the fuses The daylight still don't work when I connect the trailer