^Good question. I think the Nav computer in the trunk keeps the OBC functions doesnt it? The factory nav screen does not have it, its just a monitor. Someone with OEM nav can chime in but I'm not too familiar with how it works. Perhaps if you keep the nav computer connected somehow, you keep OBC functions?

__________________
2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards