On my unit the lights in the ceiling by the door and kitchen come on when the door opens. The switch on the panel labeled ceiling does not have to be on. This is what in logic is known as the "or" function. Either the switch OR the door opening switch will cause the lights to come on.
2012 F350 6.7 L dually, 2013 3800RE with 6 pt leveling, Sumitomo 17.5" load range h tires, Samsung 18 cu ft residential fridge, 8k Morryde I.S. with disc brakes. Full timing since 2012.