Front Diff not engaging

[Big White Hoe]

I am hoping someone can help me out.
I have a 2006 Tahoe LT 4X4 and when I had it up in the snow last week the front wheels would not engage when I put it in 4X4 Hi, Low, or Auto 4X4. I had my daughter try to go while I looked under the Tahoe and the front driveshaft was definitely turning when 4X4 engaged. When I got home we removed the actuator in the front diff and when we put in 4X4 the "piston or rod" would come out and appears to be working normally. I am getting no codes or any of the service 4-wheel drive messages on the DIC. Does anyone know what I should be checking next?

I can drive it around just fine in 2 wheel drive but I need to get this fixed soon.

 

[rockola1971]

If the actuator at the front diff is extending when put in 4wd and you are sure your front driveshaft is being driven under power then you have a problem in your front diff like a busted fork or worse. Is your dash indicator showing it in 4wd HI when you push it or does it just flash then go back to 2wd?