Manual Shift 4X4 Not engaging

[cpatterson]

I have a 2011 Sierra SLE with the manual shifter for 4X4 and the 4.8L engine. When I shift into 4 high or 4 low the lights come on (in the dash) and show that the 4X4 is on; however, there is no power going to the front wheels and ended up getting me stuck in 5 cms of snow. Which made is worse is my dad had to hook up his RAM and pull me out.

 

I have done the test of driving in 4 wheel drive while turning and seem to be receiving no bind up and have not seen an leaks or issues with the transfer case so I am looking for some advice as I am not sure what could be causing my issues, especially when all lights turn on indicating the systems is active, have had no warning lights to service the system and in 4 low shuts off my traction control so I assume that the system is working but then when I was in the snow delivered no power to the front wheels.

 

Any advice is welcomed.