I own a 2007 sunset trail. Now the left backlight will not light when braking or flashing. I've check wiring in the connection box and it all looks fine. Are there any fuse in the electrical path? I swapped bulbs also to make sure.
Check your tow vehicle. Most modern vehicls have a seperate fure fore trailer signals. Lso you didntsay if the running lites (parking) are working on the same side. If not then you could be missing the ground side. (-)