Odd 4x4 not working issue

[brad3520]

Ok iv done alot of research on the 4 wheel drive not working issues and nothing i find relates to exactly what iv got going on. 2005 chevy tahoe z71 it seems like every time the truck gets in some deep snow or very cold the 4 wheel drive wont engage... As soon as i pull it in the shop and let it thaw out it works fine. It never shifts into or out of 4x4 by its self, if i push the 4hi 4low or auto it just blinks and goes back to 2wd. Any idea or input would be greatly appreciated thank you

 

[str808]

Try placing transmission in Neutral, then switching the knob into or out of 4x4.