I have a coleman Viking 16 foot trailer and while it has several interior overhead 12 volt lights, i have had no problems until last night. My daughter claimed the lights "just went out". I found that if i turned a light on it was dim and not as bright as usual but then turning on a second light made the first one to go out and turn back on with the second one very very dim. The only thing that is weird tho, is that my exterior 12 volt security light is bright and is not affected by this phenomenon. Thinking outloud, if the converter was the issue, the exterior light would act the same, would it not? I have no battery on this trailer and everything was working just fine until last night. All of my 125 volt power seems to be fine and unaffected. I have yet to test the converter outout, but given that the exterior light is unaffected i am thinking a grounding issue or short somewhere? Also, I should mention that as of yet, the fuse has not popped.