Troubleshooting Dim Lights on RV Trailer with LED Lights Replacing Incandescents

Updated 01/08/2019 | Published 01/07/2019

Products Featured in This Question

Combination LED Trailer Tail Light - Submersible - 6 Function - 11 Diodes - Passenger Side

(1257)

$17.94

Dielectric Grease for Electrical Connectors, 2 oz.

(1481)

$10.96

Hook Probe Circuit Tester

(61)

$13.33

Question:

Hi, we recently restored a 1976 kit road ranger rv trailer. We add LED running lights to replace original runners with original wiring. We also replaced the incandescent brake/turn signal lights. All lights were purchased from etrailer. Our mystery is all lights work but, when head/runs lights are on brake and turn lights are so dim that you wouldn’t really notice they are on. Any helpful info is greatly appreciated. Thank you

asked by: Anthony

Expert Reply:

The issue you are experiencing is the amperage draw of LED lights is far less than the incandescent lights you replaced. When you turn the headlights on the power is drawn to that function as those bulbs draw much more power which is normal. What is not normal is that your trailer lights are not working because of that, which normally signifies a ground issue somewhere.

You need to ensure you have a really clean ground connection on your trailer that is bare metal to metal and free of rust or debris. You will want to check your main ground to your trailer as well as the tail light ground connections which are normally through the mounting hardware. A weak ground will cause weak lights and sometimes only partial function. I've attached some articles to help.

It is also possible that the weak ground may be on the vehicle side of your trailer connection. Make sure that the ground connection there is also free of debris and corrosion and is bare metal to metal. You will also want to clean the pins of your trailer connector and use some dielectric grease like # 11755.

If you have an incandescent circuit tester like # PTW2993 you can test your trailer functions as the incandescent light will help determine if there is a short in the wiring.

expert reply by: Jason S