I'm borrowing my father in law's 4x8 utility trailer to haul a new ATV to my cabin. All the lights work on the trailer (turn signal/running) but the right rear brake light doesn't work. I cleaned the ground on the tongue, tore apart the rear light housing and cleaned the bulb contacts, and tried a new bulb. My vehicle connections are working (hooked them up to a friends trailer) so there's something goofy with the trailer wiring. I'm going to buy a new light housing tomorrow (Blazer brand) and see if that works. For me to check the trailer wiring (to see if there's a break somewhere) I'm going to have to flip the trailer over and trace the wires since they're run though the frame. I watched a bunch of YouTube videos on trailer wiring and I'm 100% sure my (the tow car) connections are good. Any suggestions? I'm the type of driver who hates having having rear taillights not working. Thanks.