Lights not working when I connect my Trailer Wiring Harness to my 2009 Jeep liberty
Updated 06/10/2026 | Published 06/08/2026
Products Featured in This Question
Question:
We have a 2009 Jeep Liberty and have installed the Trailer wiring kit for the basic flat interface connector. The voltage reading at trailer plug is 10.6V. That seems low. When the Trailer is connected none of the lights work properly.
asked by: Tim P
Expert Reply:
Happy to help Tim, thanks for reaching out!
I agree, 10.6 volts at the 4 way connector on the Liberty is lower than expected. Curt trailer wiring harness # C59236 is a powered converter that requires a direct connection to the vehicle battery through the fuse and power wire, so first I'd verify the power wire is connected properly and that the fuse is not blown.
If the trailer lights do not work correctly when connected, disconnect the trailer and test the 4 way connector functions by themselves. If the vehicle side wiring tests correctly with the trailer unplugged, the issue is likely on the trailer side, such as a poor ground connection or corrosion.
Since grounding issues are the most common cause of dim trailer lights, be sure to check both the converter ground and the trailer ground connections to ensure they are attached to clean, bare metal surfaces.
What do you usually to with the liberty?
Product Page this Question was Asked From
Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- Powered Converter
- Universal Fit
- 4 Flat
- Plug and Lead
- Splice-In
- CURT
more information >
Featured Help Information
Instructions
Continue Researching
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Article: Trailer Wiring Diagrams
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Q&A: Recommended Hitch and Trailer Wiring for a 2026 Toyota RAV4 Hybrid
- Q&A: What is the Difference Between a 4-Way and 7-Way Trailer Connector
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Article: Wiring Trailer Lights with a 4-Way Plug (It's Easier Than You Think)
- Article: How to Choose the Right Trailer Hitch Class
- Q&A: Is There a Trailer Hitch that Fits 2026 Toyota RAV4 Hybrid
- Article: How to Measure for Trailer Hitch Drop
- Article: My Trailer Hitch Doesn't Fit
- Q&A: Trailer Hitch and Wiring for 2027 Kia Telluride
- Q&A: Will Curt Hitch Fit 2026 Hyundai Santa Fe Hybrid
- Q&A: What Hitch and Wiring Will Fit My 2026 Subaru Outback Wilderness?
Ryan
6/10/2026
Tim, If you have isolated all other possible issues per James' reply then you may need to look at the powered converter. I have a 1996 Tacoma that ran another powered converter for 25 years before it failed. When I tried to upgrade to a Curt flat plug-in converter, the vehicle-side trailer connector worked with a test lamp, but not on the actual trailer. Turns out, voltage was too low. I installed the Curt powered converter (back to splicing) and everything works great. It was actually Curt customer service that told me that Gen I Tacoma's don't push enough power through their plug-in converters to power anything but LED trailer lights.