05 Tahoe Z71 4WD concerns

[Krch0210]

I drive a 2005 Tahoe Z71 with 55K.

While driving today I noticed my Dash display said "Service 4WD". This is the first time I have seen this message. My vehicle was not in 4WD when it occurred. I parked my car for about 1.5 hours. Got in it and drove for about another 15 minutes and when parking again I noticed the "Service 4WD" again. I drive my vehicle in AUTO 4WD all of the time. I put the vehicle in NEUTRAL and tried to put it in 2WD, 4HI and 4LO. It would not let me do any of those. After leaving work a few hours later I pulled into my parking pad and the "Service 4WD" light never came on. I turned the vehicle off and then back on where it showed the red neutral light briefly and went into 4HI. I was then able to change it to AUTO 4WD but nothing else. I could only toggle between AUTO 4WD and 4HI. I also did not hear the transfer case engaging when toggling between the two. I have read on other websites that it can either be the encoder motor within the transfer case or possibly the 4WD switch within the vehicle.

Does anyone have any suggestions? Or have had any experience with this problem.

Any details would be greatly appreciated.

 

[jmeyers278]

not being dumb but I think you posted this in the 07 and newer forum

 

[Donut Slayer]

Copied from another site, but this is spot on:

Start with the cheap fixes and go from there.
Dash switch - Common on 01-02 trucks. Not very common on 03+ trucks. Based on what I read here someplace.
Front actuator - This is becoming more common as our trucks get older.
Encoder sensor - VERY common and most likely your issue.
Encoder motor - This comes with new sensor but you spend an extra $400 why? Be sure the motor is bad before you do this. I suspect there have been alot of full motor replacements done that didn't have to be. The dealers always replaced the whole motor and originally told us the sensor itself was not replaceable. Therefore, alot of people spent money when they didnt have to.
TCCM - not that common but it happened to me. It was around $700.