Hi Everyone, Brand new here so thank you in advance. Someone from RV.NET sent me this way. I have a pretty clean 2001 Viking 2480ST that I have had for maybe 5 years. I bought it slightly used and it's really in nice shape. We have only used it a few times and it has been great. I keep it open in a heated building and yesterday I noticed the interior lights were not working. Outlets (110V) and A/C is fine. Long story short I think maybe the 12V power supply/converter is bad OR I have a bad ground, but I am not sure I understand the wiring here. When I went to look at the wiring under the seat coming out of the converter I saw a few loose wire nuts and really shotty work from the factory. I looked everything over and the only thing I am not sure of is on the output of the supply there is four 12V circuits (Brown, Purple, Orange & Yellow) and a Red that says 12V Batt Positive. (see pics below) Literally when I went to grab the wad it fell apart and 2 nuts fell right off. I removed the tape but the wires were kinda all over the place so I am not sure what goes where. The red and yellow were bare. The only stray I had was a pink that goes thru the floor and seems to run all over the trailer. I did trace it over to the 12V switch for the fridge so I assume it's just another 12V line that would go to the open yellow? That said,what goes to the Batt Positive Red? There is a place for a battery on the trailer but there is no battery in there or any other stray wires by the converter. What would go to this red wire since I have no other strays in this wad of wires? I can't really get under the trailer too well BUT I was able to see up at the front drivers side corner under the trailer where they bring all the chassis grounds (whites) together and crimp and blot them to the frame and they really don't look to good. Wire is stripped way too far back and excess exposed wire is looking bad, but wiggling it to see if I could get lights to flicker did nothing, I read in the camper manual that the lights are run on the 12V only reguardless of how the camper is hooked up. All the outlets work and if I flip the 15 amp the outlets go out. The 20 amp I assume is the 12V stuff? (See pics below) I have no heat or CO detector as well. If these white 12V chassis grounds are bad would ALL the 12V outs from the supply be out? I stuck a meter in the 4 colors and I have no 12V at these outputs. I would assume with the chassis ground wires crappy that MAY be my problem but I'm not convinced since I am not sure I get how the 12V works? I mean I know the 120 comes in and the converter converts it to 12, but do the grounds from the frame need to be therte to complete the circut? I could see the lights not working but I would think the 12 would still be at the plug coming out of the converter. Can I ground the ground bar on the converter and bypass those chassis ground wires to see if this is my problem? I am not able to hook up my truck to it the way it is stored. I need to move a bunch of stuff but I would be curious if they work off the truck. If so, what does that tell me? I'm just not sure how to test this converter to know if it is working. All fuses check good, but I read there may be one internal. This is a bit more of a job to rip it out. Should I have 12V at these outputs even if the chassis grounds are bad? I also have no CO detector or water pump, so everything 12V is out. This seems simple yet I am not sure why I have no 12 coming out and what was going to this red Batt Positive wire. Thank you for any help!