I have a 20' travel trailer, a boat trailer, and a 5x8' cargo trailer. Only the travel trailer and cargo trailer have LED lights, the boat trailer has regular incandescent bulbs. ALL THREE TRAILERS have this problem you've described, AND......all three also go into a triple-speed fast blink rate when using the turn signals. The boat and cargo trailers use the 4-pin straight adapter, while the travel trailer uses the 7-pin circular connection. Others on this forum have related this problem to be due to either low-voltage errors from LED lights on the trailer OR a missing or aberrant ground wire (none of my trailers have ground wires...). Most BMW dealerships appear to be absolutely clueless about this. One member on this forum alluded to some sort of adapter that BMW made which fixed this issue. Again, no part number was given and BMW NA and my local dealerships are clueless. What I can tell you is that I've left my trailers connected for days or weeks at a time on trips and these blinking trailer LED lights have not affected the battery at all. The only benefit I can fathom is that it looks to others like your trailer has a security alarm on it. Go figure.