The Merc dealer said the problem is definitely in the BCM but that this was something the Chrysler techs need to deal with, so they took it over to their Chrysler guys who said they cannot identify the issue (why it's not working). I took the car to inspection anyway and it worked while there, so I've got some time to sort this out. Any BCM pros out there, please chime. In the meantime I'm going to buy used BCM and see what if I can make it work.