Turn Signal and Brake Lights Stop Working on Trailer When Headlights are On

Question:

I have a 2002 dodge 2500 with a 7 pin trailer plug. I replaced my horse trailers incandescent taillights with the LED lights. My turn signals and brakes work when my head lights are off. My running lights work with the head lights on, but I have no turn signal or brake lights with the head lights on. The lights are also not very bright. Only the 4 LEDs in the center appear to be lit for turn signal, brakes, and running lights. The 4 small center LEDs will blink when the turn signal is on and the head lights are off, but they are the only thing that blinks. The red wire is hooked to the yellow wire for my left turn signal and the red wire is hooked to the green wire on the right side for right turn signal. Thanks for any help.

asked by: Corey A

Expert Reply:

This sounds like a ground issue. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light.

Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces. The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help.

expert reply by: Jameson C