normal trailer wiring is brown--lights g---right turn y--left turn white --ground-------black is the a s you see on the plug whichthe wire comes from the brake box. check the trailer plug. if you have adjusted the brake pendelum and the power and still have a weak light it is probably the magnets and that will take about a day to a half day to fix. had the same problem on one of my trailers if magnet is work you can hear it make contact but if you have a buzz i would think a short in the magnets