Cassandra D

Ok now i have a brain teaser for you GM people out there. I have a 2011 Chevy Silverado 1500 LT 4x4 with the 5.3. I have the electronic shifter panel that has the "AUTO" option for 4x4. When i was on my way to Georgia the lights on my 4x4 switch all of a sudden went out and the dash flashed the service 4x4 soon code. (my truck has 183,000) on it. So I didn't use it at all. got home to Texas and changed the four wheel drive actuator drained the axle fluid and now the 2 wheel light will not come back on. The truck is engaging and disengaging. I can hear the Transfer case locking and everything shifting in and out fine. BUT the only thing i am now noticing is that when i test my 4x4 in a grassy or sandy area to see if everything is ok. It turns kinda hard. It was worse until i changed my Transfer case fluid but has not gone away and the 2 wheel light is still off. But it dosen't humm when im going straight ahead and it dosent get stuck going in or out of 4x4. I have no idea what the cause is. -HELP!!