My Newmar the wiring was for a 12 volt freezer option .
Check to wire color against the Newmar fuse panel .
Mine was in the bedroom next to the 120 volt circuit breaker box.
99DSDP 3884, Freightliner, XC, CAT 3126B, 300 HP /ALLISON 3060
2000 Caravan toad, Remco & Blue Ox.