I absolutely agree with it being a bad ground. it dosent even matter if the trailer is new either. they are built so fast and S**T happens. like screws penetrating the wire bundles.
I cant ever remember led trailer lights causing any problems except the couple times screws went through the wires... on brand spanking new enclosed trailers. my old company bought 2 new trailers every year. somehow my old boss thought this was cheaper than maintaining a trailer. he would sell them as soon as the cheap Chinese tires starting to go bald. over 5 years that's 10 brand new trailers I worked with and 2 of them had screws right into the wire bundle.
but it honestly sounds like a bad ground. all the led trailer lights Iv worked with didn't need anything special.
when I had a bad ground on my boat trailer I completely and stupidly ripped apart all of my trucks wiring harness that I had soldered up a few years before. I knew it was fine. after doing so everything truck side was actually fine. I got really mad and did something I should have done first. I grabbed a 20 foot wire. self tapped it to my trucks frame and then I took the other end and touched the mounting bolts on the trailer lights, which give it ground. holy S**T everything started working. So I then started looking for where ground was lost by placing the wire on the trailers frame. I found that the axle of the trailer was not electrically connected or grounded to the rest of the trailer. So I took that wire and self tapped it to the front of the trailer and directly to one of the mounting bolts of the lights.
man bad ground will make you do stupid things, at least once in your life before you learn it's a bad ground. the faint lights are your tell tail sign that it is not receiving any ground whatsoever. (I do realize this is an led without a filament so its behavior will be different) electricity will find a way and its grounding itself through the bulb with the other connection for running/turn or brake lights.
Al
