How to Troubleshoot Trailer Wiring Issues, on a 2020 jeep JL
Published 04/05/2021
Question:
Hi. Got this new jeep last month and installed the Teknosha kit. Super easy, brake lights, turn indicator all work, but no running lights. Seem like all in order..what should I do?
asked by: John N
Expert Reply:
There are a few ways to troubleshoot this issue. The first one would be to check your owners manual for the fuse diagram. The should be one listed for the running lights. If that fuse is good, there should also be a listing for the fuses related to towing. There are times these are not all installed from the manufacturer or dealership and just simply needs to be installed. The inline fuse that comes with # 118786 should also be checked.
If all fuses are in place and not blown, there may be an issue with the harness. One of the most common issues with wiring harnesses is the ground not being seated all the way. Make sure it is contacting bare metal with no paint or anything interfering with the contact. If that is seated nicely, the 4-Flat ports will need to be tested. The best way to check is to test all the ports on the end of the harness with a tester, like part # PTW2993. If one or more of the ports have no power, the harness will need to be replaced.
If all the ports have power, there is most likely an issue on the trailer somewhere. Using the same tester, test the wires just behind the 4 Flat on the trailer. Plugs do get worn out and can lose connectivity that way. If there is power, the wires will need to be followed as there is most likely a break somewhere down the line. It also never hurts to check the ground on the trailer as well.
Featured Help Information
Miscellaneous Media
Continue Researching
- Shop: Hook Probe Circuit Tester
- Video: 2013 Jeep Wrangler Tekonsha Prodigy P2 Trailer Brake Controller: Complete Installation
- Q&A: Troubleshooting Blown Fuse for T-One Trailer Wiring on a 2021 Jeep Wrangler
- Q&A: 4-Flat Wiring for a 2021 Jeep Wrangler Sport and Where to Mount the Converter to Keep Elements Away
- Shop: Trailer Wiring
- Q&A: Troubleshooting No Trailer Turn/Stop Lights When Connected to 2018 Jeep JL Wrangler
- Video: Curt T-Connector Vehicle Wiring Harness Installation - 2021 Jeep Wrangler Unlimited
- Shop: Base Plate for Tow Bar
- Search Results: trailer safety chains
- Search Results: jeep
- Article: Trailer Wiring Diagrams
- Shop: Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Search Results: trailer wiring
- Shop: 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
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Search Results: trailer hitch
- Q&A: Lug Nut Torque Chart for Trailer Wheels
- Article: How to Measure for Trailer Hitch Drop
- Shop: Roadmaster 4-Diode Universal Wiring Kit for Towed Vehicles - 7-Way to 6-Way Coiled Adapter Cord
- Shop: Suspension Enhancement
- Video: An In-Depth Look at the Roadmaster Battery Charge Line Kit for Towed Vehicles
- Search Results: trailer tires and wheels
- Q&A: Installation Time for Blue Ox BX1128 Flat Tow Base Plate Kit for 2016 Jeep Grand Cherokee
- Shop: Brake Controller
- Shop: Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Video: An In-Depth Look at the Roadmaster Diode 7-Wire to 6-Wire Flexo-Coil Wiring Kit
on Custom Fit Vehicle Wiring
