Find your converter. It should be a panel about 16"x16" down near the floor on an inside wall. It will be real close to where the shore line enters the trailer.
Use a coin, and turn the little plastic knob 1/4 turn and the upper door will swing down. When open it will look like this:
There are regular residential style circuit breakers for the 110vac stuff, and regular automotive fuses for the 12vdc stuff. Since you have a light fixture out, check the 12vdc fuses.
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'12 F250 4x4 Super Duty PowerStroke 6.7 diesel
2011 to present: '11 Cougar 326MKS
1999 to 2011: '99 Sunline T-2453
SUN264 * Amateur Radio kd2iat monitoring 146.52