Ground Is Key to Your Riddle
If you can't see your grounding wire running to the tongue, it may have been removed by some PO who didn't realize its importance. Others will chime in who know your particular Airstream, but there should be a heavy grounding wire running from a bus at your inverter to the frame of your trailer somewhere on the A-frame near the tongue.
As I mentioned yesterday you must repair or restore your ground before you do anything else.
For obvious reasons, we don't rely solely on the tow vehicles ground.
ALthough we can spot those who do by the dim, flickering running lights.
2007 Classic Limited 30 (Sold)
2007Chevy Silverado 2500 HD Duramax/Allison
Four Corners Unit WBCCI #8654, Affiliate NM Unit