Troubleshooting Trailer Tail Lights That Do Not Work When Other Lights Do Work
Question:
My brake lights and turning lights work fine on my trailer, but I have no tail lights. The running lights work on the side of the trailer, but no tail lights. Do you have any suggestions? PS: All are LED lights if it matters.
asked by: Henry
Expert Reply:
The most common cause for trailer tail lights to not work when other trailer lights do is a bad ground. The reason the bad ground tends to show up on the running light circuit is that these lights remain on continuously, rather than flashing on and off like brake and turn lights. This means the tail lights will draw more current and that higher current draw may not be possible with a weak ground. The bad ground could be on the trailer harness or on the vehicle harness.
Find the trailer's main ground wire; usually this will be a white wire. You can either sand off the grounding point to remove rust, paint, primer, grease, etc OR you can relocate the ground wire's ring terminal to a new clean bare metal spot on the trailer frame. Once you make your new ground protect it with an application of dielectric grease like # 11755. Repeat the process on the vehicle's wiring harness ground wire if required.
It does not matter whether the lights are incandescent or LED.
Products Referenced in This Question
Dielectric Grease for Electrical Connectors, 2 oz.
- Accessories and Parts
- Trailer Wiring
- Wiring
- Dielectric Grease
- LubriMatic
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Product Page this Question was Asked From
7-Way to 4-Way/5-Way Trailer Adapter for Vehicles with Lamp-Out Sensors Towing Trailers with LEDs
- Trailer Wiring
- Wiring Adapters
- Multi-Function Adapter
- 7 Round - Blade
- Plug Only
- 5 Flat
- 4 Flat
- CURT
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