Might need to locate the passenger fuse compartment - it's in behind the Glove Box, which you'll have to remove that door to get at it to pull the fuses - so refer to your cars manual - it (interior light fuse) would be the one for Battery Saver that runs thru the Body Control Module.
The one I have, it's in the engine compartment fusebox, and is a 20A - my Box is different configuration...
Hope this helps!
The "Battery Saver" is for that purpose, to turn off lights and even the audio system when someone is in the car - the BCM has a timer that keeps the system "active" for only so long then it shuts down and resets once the key (or keyless entry fob is present) is turned or pressed to Start