My 2015 Sprinter chassis has 1 light on the cab ceiling. There is a 3-position switch on it. All the way to one side - light comes on with open cab door, times out - but only maybe a minute or less. Middle switch position - light remains off. All the way the other way - light stays on. Actually just replaced the incandescent bulb with an LED festoon bulb - minimal power draw, brighter, works well for reading with front seat swiveled around. I do not know any way to adjust how long lamp remains lit other than that.
Two and a Hound in a 2015 Prism "B+", pushed by a 2021 Chevy Equinox.
1st 50 done, working on the 2nd pass! Somewhere over 150k miles to date
2005-2015 Roadtrek 190P, 1993-2005 Northstar Soft-Side TC, 1989-1993 Tents!