Troubleshooting Trailer Lights Not Working When Head Lights Turn On
Question:
Brake and turn work fine until I turn headlights on then they stop working turn headlights off they work fine 1994 Toyota pickup with new plug and play harness 4 prong flat
asked by: Timothy S
Expert Reply:
Typically when this happens after installing a wiring harness like the Curt # C55379, it's down to one of two causes. You'll want to start by checking the ground connection on the vehicle and trailer wiring harnesses. Make sure that these are connected to a paint, rust and debris free spot on the frame. You'll also want to check for potential shorts on the wiring, where there might be bare wiring touching a metal spot on the vehicle or trailer frame.
The less likely cause would be too many running lights on the trailer, and the harness becoming overloaded. If checking the ground wires as mentioned above, and making sure there is no damaged wiring causing a short does not get your lights back up and running properly, let me know and I can continue to assist you with this issue. I've also linked a helpful article we did on troubleshooting 4 way wiring that you might find helpful as well.
Products Referenced in This Question
Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Converter
- Custom Fit
- 4 Flat
- CURT
more information >
Product Page this Question was Asked From
- Trailer Wiring
- Trailer Connectors
- Trailer End Connector
- 0 - 5 Feet Long
- Plug and Lead
- 4 Flat
- Draw-Tite
more information >
Featured Help Information
Instructions
Miscellaneous Media
Continue Researching
- Q&A: Breakaway Battery Continually Goes Dead
- Q&A: Recommended Breakaway Kit for a 20K Deck Over Trailer
- Q&A: Troubleshooting No Running Lights on Trailer Wiring of 7-Way
- Q&A: Correct Way to Wire Trailer Breakaway Kit
- Q&A: Diagnosing, Locating and Repairing Trailer Ground Problem
- Q&A: Installation Instructions For Hopkins Engager Trailer BreakAway Kit
- Q&A: How to Wire Break Away Switch on Hopkins Engager Break Away System
- Video: Yates Rubber Boat Trailer Parts - Roller and Bunk Parts - YR10000 Review
- Video: This Old Trailer: Troubleshooting the Ground Wire
- Article: Troubleshooting 4 and 5-Way Wiring Installations
- Article: Testing Breakaway Systems
- Shop: 7-Way Molded Trailer Wire Connector, 6' Long
- Shop: Hopkins Endurance Universal 5th Wheel/Gooseneck 7-Way RV Extension Cord - 8' Long
- Shop: Trailer Wiring
- Search Results: trailer battery box
- Article: Trailer Wiring Diagrams
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Shop: Curt Powered Tail Light Converter with 4-Pole Flat Trailer Connector
- Search Results: brake controller
- Video: Choosing the Right Trailer Wiring
- Shop: Trailer Hitch
- Search Results: 90160
- Shop: Brake Controller
- Shop: 7- and 4-Pole Trailer Connector Socket w/ Mounting Bracket - Vehicle End
- Article: How to Choose the Right Trailer Hitch Class
- Shop: Universal Installation Kit for Trailer Brake Controller - 7-Way RV and 4-Way Flat - 10 Gauge Wires
- Search Results: trailer brake controller
- Video: Choosing the Right Brake Controller
- Shop: Tekonsha Prodigy P3 Trailer Brake Controller - 1 to 4 Axles - Proportional
- Video: Curt 4-Pole Flat Trailer Connector Mounting Bracket Review