Trailer Lights Go Out when Brakes are Applied
Question:
I have installed the plug and tow adapter to the passenger side plug under the mud flap and grounded it. I have lights and turn signals, but when I hit the breaks all the lights on the trailer go out. I have checked all the wiring and bulbs and cant seem to find an answer. Please Help! Thanks
asked by: Regan L
Expert Reply:
What you describe is a ground problem with the trailer wiring. Starting at the rear of the vehicle, confirm that the ground connection on the Plug and Tow Harness is securely fastened to bare metal. If there is undercoating, corrosion, or grime built up under where you attached the ground, you will not have a good connection. Next, examine the point on the trailer where the trailer connector ground wire attaches. This can usually be found on the trailer tongue. Make sure the wire is in good shape, and the connection is secure and not corroded. The next place to check is the light fixtures themselves. Most trailer lamps obtain their ground connection by the mounting studs used to fasten the lamp to the trailer frame. If this connection is corroded or not tight, it can cause problems.
If your trailer has a tilting bed or a tilting or swinging tongue, the pivots might be worn a bit and might not be keeping a continuous ground connection. Use a jumper wire to join the stationary portion of the trailer to the tilting or swinging part.
You should find the problem at one of these areas. We have some videos that demonstrate how to troubleshoot linked below. I've also linked you to some troubleshooting FAQ articles that I hope you'll find helpful.
Product Page this Question was Asked From
Hopkins Plug-In Simple Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- No Converter
- Custom Fit
- 4 Flat
- Hopkins
more information >
Featured Help Information
Instructions
Miscellaneous Media
Continue Researching
- Q&A: Troubleshooting Trailer Lights Going Out When the Brakes are Applied After Trailer Light Kit Install
- Q&A: Why Does Trailer's Wiring have Two Brown Wires
- Video: CIPA Univeral Rearview Boat Mirror Review
- Video: CIPA Comp Universal Rearview Boat Mirror Review
- Shop: CIPA Comp Universal Rearview Boat Mirror - Convex - Windshield Mount - 13-1/2" x 6-1/2"
- Shop: Trailer Hitch
- Q&A: Lug Nut Torque Chart for Trailer Wheels
- Search Results: 25580
- Shop: Kenda Karrier ST205/75R15 Radial Trailer Tire with 15" Black Mod Wheel - 5 on 4-1/2 - LR D
- Article: Trailer Tire Sizing
- Shop: Hub Bearing Kit for Lippert, Dexter, and AL-KO Axles - 3,500 lb with #84 Spindle
- Article: Trailer Wiring Diagrams
- Shop: Trailer Wiring
- Search Results: safety chains
- Q&A: What is the Difference Between Load Range C and D ST175/80D13 Trailer Tires
- Shop: Gooseneck Hitch
- Search Results: lug nut
- Video: Timbren Axle-Less Trailer Suspension System Installation
- Article: Most Popular Wheel Bearings
- Shop: Tekonsha Prodigy P3 Trailer Brake Controller - 1 to 4 Axles - Proportional
- Q&A: What is the Difference Between Load Range B and C Trailer Tires
- Video: Choosing the Right Trailer Wiring
- Article: 7 Common Questions Everyone Has About Trailer Tires
- Search Results: fender
- Shop: etrailer Electric Trailer Brakes - Self-Adjusting - 10" - Left/Right Hand Assemblies - 3.5K
- Shop: Suspension Enhancement
- Q&A: How To Determine the Correct Size Lug Nuts For a Trailer
- Shop: Kenda Karrier ST205/75R14 Radial Trailer Tire with 14" Black Mod Wheel - 5 on 4-1/2 - LR C
- Q&A: Factors to Consider When Adding Larger Tires and Wheels to a Trailer
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
on Custom Fit Vehicle Wiring
