Got a multimeter but it wasn't necessary. The DC fuse block on the front of the converter box had melted plastic around the hot lead on the left side. Whole mess was loose and probably arcing. I am not certain why I had NO lights
AT ALL. Numbered all the leads and replaced them on a second fuse block found in a locker which was identical to that installed and perhaps had been purchased as a replacement butwasn't put in service due to the lack of a roundtuit. Got a new NAPA 24 also as the one in place would not charge. I thought at first that the condition of the battery
might have something to do with no lights (you can read 4000 pages of converter gobblygook and get enticing but less than definitive answers about the role of house battery in the shore power conversion) but after tidying up that fuse block, the lights are operating without battery in the circuit. As for the independent porch light, I still haven't figured that out after playing with and isolating items that work with breakers. There is an automotive fuse holder in there on a block wire which comes form somwhere thru the box connector and piggybacks with a spade lug on top of the black lead to the screw terminal at top of fuse block. Should have left it unhooked to see what the exterior light did. Next time.