4WD stuck in 4LO all known components have been replaced with new or Reman

GMC Sierra 1500 Problem 64 Reports Me Too GMC 1500 Problem - Model Years Affected: 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2012. Drive Trains Affected: 4WD, Automatic Transmission; check Transfer Case control module sensor and/or 4WD transfer case encoder motor position sensor, and/or the selector switch. Sounds like the dealership has replaced all the big, expensive parts, now on to the little sensor bits. Wish I could be more specific and good luck.

Since all work is recent and should be covered under warranty, I will have them check the sensors. The dealer said that they put new sensors in with new encoder motor... Thanks and I'll see what they say. It will probably take them a week to schedule my truck.

Started truck this morn. no 4WD SVC light. It took several attempts and finally went to 4HI, then was able to switch to 2HI. I think there is something wrong with the encoder motor sensors or possibly the wiring harness... I will post more when I find out. I'm still open for suggestions.

Dealership is replacing the encoder motor and sensors under warranty. No other known culprit.

The encoder motor and sensors were replaced without charge today, and all is working well. It's not normal for encoder motors to fail. The clutches were worn out on the transfer case at 170,000 miles. 1st Ck ATC fuse under the hood, then 4WD fuse left side of dash, replace selector switch, differential actuator motor, transfer case control module, encoder motor and sensors. Before replacing expensive stuff pay to have dealership decode the errors and go from there.