I have a motorcycle trailer, I've plugged in the lights (which worked last year) they do not light up ... where can I take the trailer to have the lights checked out? Not a mechanic, tire store?? RV supplier??
You would be better off to take it to a trailer dealer. I am not saying that because I am one, but you need to go where someone understands what could be wrong and not waste time and your money checking this and that.
A few things to look at:
You want to make sure current is coming out of the tow vehicle. A fuse could be blown. Newer trucks and SUV's have a seperate fuse for the vehicle and trailer.
Dirty plugs in either your trailer or vehicle.
Bad ground on trailer or bad wiring. I have seen where animals have chewed the wires on trailers.