Troubleshooting LED Trailer Lights Not Working

Published 10/22/2019

Products Featured in This Question

Load Resistor Kit for LED Turn Signals - 50 Watts - 6 Ohm - Qty 2

(36)

$10.96

LCD Digital Circuit Tester

(26)

$26.67

Question:

I know that a load resistor will fix the turn signal but none of the other lights work. i bought a new tail light assy

asked by: Philip

Expert Reply:

If none of your trailer lights are working correctly then you need to start off by checking the connector on your vehicle side of things. Use a circuit tester like part # PTW2992 and test each of the functions making sure they are operating correctly. If they are then move on to the trailer, if they aren't then inspect the wiring on your vehicle as well as the grounds and any fuses (see your owner's manual for locations).

If your vehicle side is working correctly then you can test your trailer wiring by either connecting it to a different vehicle or applying 12V power to each of the light functions. This will help you narrow down which circuits need to be inspected so you don't have to spend as much time looking at all of your wiring. As I mentioned above, look for any places where the wiring is damaged and make sure your grounds are secure and connected to a clean, bare-metal surface.

Once you have fixed any issues, if you're still having trouble with your LED tail lights working then it is time to install load resistors like part # DI34ZR to make sure they are pulling enough power for the vehicle to send a signal back to them.

Attached are some wiring articles as well as some photos to assist you.

expert reply by: Jon G