Demand Lamps
WARNING: This page is about a different car, the 2018 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
When the BCM is in not in battery saver mode, the interior light output is energized to provide voltage to the demand lamps.
The cargo, truck bed and trailer assist lamps all illuminate with the courtesy lamps. They can also be illuminated by using the cargo lamp switch (integrated into the headlamp switch) or the truck bed lamp switch, located inside the LH rear of the truck bed.