So I'm getting a whining noise at 30 mph and up from the front diff area when in 2wd. The noise completely disappears when in 4hi. So after some research I thought it could be the vacuum switch on the t-case so I replaced that with an ac delco unit. Problem still there. I checked for vacuum leaks and couldn't find any. The front diff is full of fluid and the 4x4 works fine when engaged. So what the heck is going on. Please help if you have any ideas. Thanks

 

Tech Article (DIY) Index to the rescue:
4wd Front Axle Clicking When in 2HI - Goes Away when in 4HI/4LO

 

Huh, very interesting and helpful. Thank you. So I have the three button case. And the problem sometimes goes away if I switch to 4 hi the back to 2 wd. But not always. And I already changed the t-case switch. So I'm thinking it may be a binding cable. Does that sound right to you?

 

Ok so I replaced the t-case switch and that did nothing. So I was thinking maybe the cable I frozen. So I took the battery out to check that an everything seemed ok. N
But I pulled it out to lube it anyways. While it was out I decided to check to make sure the shift fork was pulling back in place. That was fine. I pulled it out and the springs pulled it right back. So I lubed the cable put it in and went for a drive. It was still humming in 2wd but not 4hi. Omg I'm so upset I can't figure this out. Swartlkk you seem like a knowledgable guy. If you can think of anything else please help. Thanks