4X4 Light On only - HELP!!!!

[Buguyed]

So recently my 4x4 light has come on. Just that light, not the ABS and brake lights. I've been searching the topic religiously the past couple weeks and noone really ever has a resolution. I have read a lot about the SAS but many say its very uncommon for that to be bad and it's usually something else.. I'm big into DIY and would to resolve this on my own without the stealership..

What I've done:
-Turn wheel lock-to-lock (about 50 times)
-Unhooked the battery for extended periods of time
-Went to Autozone, their reader says no codes.
-Used the OBC to check the voltage, it's 11.2V with engine off, and 12.8 when running. I've read it should be 12.25 minimum when not running.

I'm thinking it could be a bad battery..

My car is a 2004 X5 3.0i with 78k miles.

I've been in the E46 world for a long time and am new to the 5 series.

Any help or tips would be appreciated!!!