WantsToBeATonka

Hello,

Purchased an 01 Silverado about 3 years ago with 155k miles all original parts in the power train. Just hit 170k yesterday. Currently having an issue where I can shift in and out of 2hi and 4hi no problem, but when you go into 4lo, you need to sit in neutral, mash either 2/4 hi and rack the gear selector until it finally pops out with a not so great sound (kinda sounds like crunching or grinding gears) and a "service 4wd" notification.
I WANT to believe that it is an encoder motor instead of a transfer case.

When in any of the drive modes, I don't have any strange noises while driving, no noticeable drivability issues, no popping in and out of the selected drive mode, and no leaks coming from the transfer case.

Does anybody have a method in how to figure out if one or the other is bad aside from pulling the encoder motor to see if the spline(?) Is bad?
thanks in advance.

tech2

get the codes read from the transfer case control module....scan tool that reads chassis codes required.