1983 Coleman Williamsburg

I have fixed a lot of tail lights in my day. Generally, there is a better chance that you have lost the ground connection to the tail lights.

The way to check that is to connect the side of the bulb fixture to a good solid ground, like the negative from your battery via a jumper cable.

If the bulb works now, it is the ground connection, not the power going out to the bulb.

Generally your tail lights on the trailer do not contain a fuse. The fuse in going to be in your tow vehicle. If your T/V came with a factory towing package, then you will have separate fuses in you main fuse box in you T/V for the tail lights and turn signal lights. You can also check your lights by using a 12v battery with a jumper wire. Be sure to ground your plug, then touch the jumper to each prong on the connector, then check the lights.