It’s not a switch. It’s a blank section in the dash that could be used for another option that Ford might have. It has no function, nor any parts that work or do anything.
That "switch" was an AUX in port that Ford offered for the stereo. I believe Jayco bypasses it when they add/change the radio. On my rig, I can pull out that black plug and see the 3.5 mm female inlet, but it doesn't do anything if I plug in a MP3 player, tablet, etc as an input source.