Won’t shift into 4 wheel drive. Clanks on sharp turns when in 4x4 mode previousr

What is your question?

Was popping on turns in 4 wheel drive occasinaly. Now sounds like it is going in but isn’t. Has 225,000 miles but had not problems till now. The lights all work on push button contro but the 2 wheel drive light is off. When I put it in neutral and 4low it switch’s to 4hi when I put it in gear but no 4 wheel action. Seems to go in 4 wheel until I shift it in gear. I have tried backing up, all that stuff.

What makes this problem better or worse?

Nothing, seems to change the problem.

How long has your 2002 GMC Sierra 2500 HD had this problem?

Few weeks, ago it started popping occasionally on sharp turns in 4 wheel drive in snow.