I haven't had my van long and it took me a few days to figure out why my lights weren't coming on when I open a door. I have not gotten into the electrical schematics yet (if they are available) but in this age of the mobile PLC brain box I would not be surprised if the mode switch is connected to it. I vaguely remember reading somewhere about customization being possible on similar functions. On my wife's VW Tiquan it is obvious that everything is reporting to the PLC (programmable logic controller) first, and even though it is of the most basic code it is relatively a new phenomena in a vehicle (for me at least). Of course it could also be the case that the wiring for the lights come directly off that multi-positiion switch on the cab ceiling and you do have a factory error.