Transfer case/ 4wd issues HELP!!

[nchbrandon]

I have a 2006 Gmc Sierra with floor shift 4wd. Recently it started making a grinding noise in 2wd, but not in 4wd. I immediately assumed it was the snap ring in the tail shaft that had broke. I have the NP261 which does not have a removeable tail to access the snap ring. I pulled the transfer case and opened it up to find it was not the snap ring. I took it to a local transmission shop for a complete rebuilt with only 109,000 miles on the truck. I got the transfer case back a few days ago and put it in the truck. It rode great! no grinding and everything worked as it should, but today it started trying to shift into 4wd on its own while driving, but the floor shifter was not moving. I could hear and feel it making a grind noise trying to engage and my 4wd light was coming on. I stopped and put it in 4wd with no noise or grinding and got it home. now my 4wd light will not go off at all even when in 2wd or neutral. Any idea where to start, is it an internal problem and need to go back to the shop that did the rebuild? Thanks in advance.

[00Silverado4x4]

How is the front differential. It could be the front is engaging from a short.

[nchbrandon]

Seems to fine, I recently pulled the driver side axle and replaced the seal, tab washer and thrust washer. I'm thinking it may be a vacuum issue or some type of sensor. Now the 4wd light stays on even in 2hi.

[nchbrandon]

Going to pull the driver side axle again today and double check the inside to make sure I put everything back together correctly