Interior lights won't work on 12V, but work on 120 V

[Libbitts]

Jayco 1996 1206 - My interior lights, which worked this morning, no longer work under 12V, but work when the camper is plugged into the mains. I noticed in the fuse box that the "Auto Reset 7.5 AMP fuse had fallen out along with both tabs that connect it to the circuit board. I tried pushing the tabs back and reconnecting the fuse. When I did that there was a small spark from ny pliers to the metal frame. Does anyone have any ideas.
Thanks

[bankr63]

That fuse is probably a red-herring it the lights work when 120V is plugged in. I would first check the main fuse that is generally located within a couple of feet of the battery on the hot wire side. I would expect it to be a 20-30A automotive fuse that is generally located in a small rubber weatherproof pouch.

7.5A is pretty small for a main, even on a pup, that is probably a branch fuse, and if a branch fuse is gone the circuit it controls will not work with either battery or 120v power.

I would also suggest that you disconnect all power when working on your power panel, including removing the ground (negative) wire from the battery.