There is no "source" button. No USB port or input jack of any kind. I did find a pair of unconnected audio wires coming out the back that were labeled as audio output for an amplifier. I guess it is a cheapo vehicle radio.
Failing ignition switch? Any way to check it?
I suppose replacement would be an expensive professional shop job due to the explosive charge in the steering wheel.
It actually strikes me as a wiring problem elsewhere that connects the driving lights to auxiliary power. Maybe something that happened in the RV building shop. I happen to slightly know two other owners of the same MH and will ask if they have the same problem.