It is always fun when you touch one system, how another semi related item acts up. Then trying to figure out if what you just did is the result of what is happening.
We experienced no 12V battery power this past weekend. When we got to camp we noticed we had no 12V battery power. Worked fine on shore power. Being the first trip out (very late first trip for us), of course I left my multimeter at home (it's summer home is in the TT).
I contributed it to be I just replaced the 7 pin wire harness as I needed a longer harness for the new TV. I checked the connections, and ignored it until we got home (had shore power).
At home, I played around with the 7 pin harness connections, and the three fuses, nothing. Not a clue, went through and disconnected and reconnected a few wires, double checked the fuses, nothing. Double checked that I rewired it correctly, it was. It was hotter than hell, so I had the AC on when we were plugged in and sitting back pondering the issue (did this a few times). After one of the pondering sessions, I noticed we had 12V battery power again. No clue why. Told the DW well it works, but I have no clue why, no clue how long it will last. FYI, the battery tested good with a full charge.
This morning, I decided to turn off the AC power and test the 12V system. No power again
. Have not done anything all week, other than go in out a few times to prep for the next adventure. Pulled the fuses at the converter and checked them, then swapped them out for known fresh new fuses. Then I did the same at the battery. While handling the wire harness, I could hear the tell tail sounds of a bad connection (faint zapping). Pulled the hot wire, wire nut apart, and redid the connection. Installed a bigger wire nut. Hopefully this was the issue. I suspect, after 10 years of use and being too with too short of a wire leads (how it came), road vibrations, pulling the battery every winter, took its toll on the wire nut connection.
I hope this is now repaired. I suspect I should find the wire stretcher and figure out a way to add an inch to the main hot and neutral wires, to relieve some strain.
Happy Camping