Look near the battery for something that looks like this:
https://img.joomcdn.net/4b5a09a41115..._original.jpeg
Good chance it is what you are looking for. They are auto-resettable, but do fail.
Note: Sometimes you have to cut a three sided "access door" in your belly liner to get to the junction box and resettable circuit breakers mounted there. Although some are mounted where you can easily see them. Follow the big red wire from your battery to the drivers side front corner of the trailer. They will most likely be found mounted under there.