Nice write up twinspoppa! I hope this is the source of your issue so you can take care of it. I'll be following this thread closely since I have the same symptoms. Except I only have the 4x4 solid yellow light. No GT1 to confirm its a module or a speed sensor. It could be either? I plan to bring it to a BMW shop to read the codes first. Have not gotten around to do this yet. Wishing you luck!

__________________
Current:
2017 640Xi Convertible
2011 Acura MDX
2018 Santa Fe

Past:
2013 Honda Accord
2008 Acura TL Tech.------2004 BMW X5 4.8is----2004 Acura MDX Tech
1994 BMW 525i.----------1994 Lexus 300 GS.----1994 Acura Legend GS
1991 Acura Legend LS.----1991 Honda Accord.----1991 300ZX twin turbo
1996 Buick Regal GS.-----1984 300Z 50th anniv.--2002 BMW X5
1982 280Z