How to wire LED trailer lights

Updated July 20, 2017

Over the past few years LED, or light emitting diode, lights have become evermore popular. The reason is economic, and its a winner from every point of view. They last much longer than filament type bulbs, and they draw much less current. For that reason, smaller wires can be used when installing the lights, and there will be less strain on the alternator to supply the needed current. They cost a few dollars more, but all in all, the investment is well worth it. Best of all, they install the same way as conventional lights so no additional tools or skills are needed.

Remove the old light assembly. Clean the mounting area. Install the LED light assembly mounting bracket.

Install the LED light assembly onto the bracket. This is a sealed unit and cannot be opened. It is waterproof and the diodes are not replaceable. They should never fail in the lifetime of the trailer. A tail light circuit will draw up to 20 amps. The LED assembly will draw less than 1/100 of an amp.

Splice the universal connector into the wiring harness. This connector is standardised throughout the industry. Install each lead according to the instructions: one for ground, one for the turn signal and one for the tail light. Use a test light if needed to determine which wires provide each function. In some cases, the ground is through the frame and is part of the mounting for the old light assembly. Make a lead wire to attach to the universal connector and ground it to the frame in a secure location.

Attach the universal connector to the new diode light fixtures. Test each function. Any circuits that are not working should be tested from the vehicle plug first, and work back to the lights. Check the vehicle fuses, and test each circuit with a test light.

Things You'll Need

  • Wire cutters
  • Wire strippers
  • Test light
  • Crimp Pliers
  • Screwdriver, flat-blade
  • Screwdriver, Phillips-head
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About the Author

Jack Hathcoat has been a technical writer since 1974. His work includes instruction manuals, lesson plans, technical brochures and service bulletins for the U.S. military, aerospace industries and research companies. Hathcoat is an accredited technical instructor through Kent State University and certified in automotive service excellence.