I figured that I would answer my own question as to code faults disabling a DEM module,so that if anyone else has this problem, "Maybe" it will help. (As far as exact match goes, I still don't know the answer to that).

I purchased a VIDA subscription and a Dice communicator, and installed the VIDA software on my Windows 7 Pro - 64bit laptop.

I read the codes and saw the DEM codes in fault mode. I cleared the codes, and the AWD Rear drive is now working.

So that tells me that "yes" a fault code can disable the rear DEM module.

After the code reset, again I ran the codes, and no codes were listed. So far so good as they say.