It could be your wiring colors... RV Trailers use BLACK for +12VDC and WHITE for -12VDC or ground.
Automotive car radios most likely use RED for +12VDC and BLACK for -12VDC or ground.
Which way did you hook it up in the RV...
Roy Ken
My Posts are IMHO based on my experiences - Words in CAPS does not mean I am shouting
Roy - Carolyn
RETIRED DOAF/DON/DOD/CONTR RADIO TECH (42yrs)
K9PHT (Since 1957) 146.52M
2010 F150, 5.4,3:73 Gears,SCab
2008 Starcraft 14RT EU2000i GEN
2005 Flagstaff 8528RESS