I purchased a 2000 Coleman Fleetwood, but that doesn't matter, I have the same issue as you. A few hours after an electrical storm, during which the trailer was plugged in, I had the lights on for maybe 5 minutes, then a scream like a whistle and a big pop and then no 12 volt power to the lights or the CO2 sensor. I checked the fuses and they were good. I checked the converter for other issues and found it smelled of toasted electronics. I had no 12 volt battery, so later with a battery hooked up, the lights and CO2 sensor work, so I can deduct that the converter is gone, as I assume could be wrong with yours as well. I haven't decided what to do to repair, but if I can order a new unit for under $200, I think that's the best bet. Maybe you should test the 12 volt system with a battery as I did, to confirm it works.