The first thing I suggest checking is the shift linkage under the vehicle. It is a steel bar/linkage that runs between the 4wd shifter and the transfer case. See pic 1 Make sure nothing is loose, damaged, and so on. It isn't uncommon for the plastic grommets to fall out or wear out, so check them as well.
If it looks good, here is what I need you to try:
1. Place shift lever in the 4 HI position.
2. Raise and support vehicle, then disconnect linkage rod from console shift lever.
3. Shift transfer case into 4 HI position. Lever should be in full forward detent, Fig. 1.
4. Adjust swivel to align with hole in console shift lever.
5. Install linkage rod into shift lever.
Let me know if that helps. Also note that there is a swivel joint in the linkage to make adjustment with. You can locate it in the pic.
Take care and let me know what you find.
Thursday, February 13th, 2020 AT 8:35 PM