Great info from all. I'd like to quote what beau388 posted "Remember the light on the master power switch ONLY that there is 12 volt power to the switch. It does NOT indicate the position of the latching relay at the power center."
This really bothered me on our 2018 Vegas so I installed an inexpensive digital voltmeter next to the so called master switchl (wired to coach batteries under step). Now I can tell if the coach is on shore power or coach batteries with a glance at the voltmeter. House batteries fully charged normally show me about 12-12.4 volts. Shore power on and connected indicated 13 -13.4 volts. Flip the store/use switch you will see the voltage change.
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