The brake magnets draw 3 amps each, so a total of 6 amps on your 16' trailer.
Brakes should not hum. They are fed with DC. If you hear a click that is the magnet grabbing the hub. Jack a wheel up, spin it, and pull the pin. Try to turn the wheel. At first it might be easy but then you should not be able to turn it.
They only work going forwards, not in reverse so be sure you are spinning it the right way.
Probably for the LED to light the switch bracket needs a good connection to the trailer frame. If it is mounted on paint, it may not work. That wouldn't affect the brake operation, only the LED.
ďYou cannot reason someone out of a position they have not been reasoned into"
Al, K5TAN and Missy, N4RGO WBCCI 1322
2002 Classic 30 Slideout -S/OS #004
2013 Dodge 2500 Laramie 4x4 Megacab Cummins