Weird issue with 4x4 selection

[Dubbin]

So got a weird issue with the truck. every now and then when we start the truck instead of the yellow light being illuminated at the 2wd spot it lights up red in the neutral position. and then the other day when I started it, the light was on the 4Low position, turned off the truck back to 2WD....what the heck?? Any ideas??
P4C

 

[Dubbin]

Anybody??

 

[Splatmaster527]

Its your selector switch...
Grab a new one on rock auto for like $30

 

[Jay]

Sounds like the PCM can't tell what position the encoder motor is at. Crawl under there and check the harness on the transfer case. Clean it real good then see what happens. If all else fails, replacing the encoder motor sensor will probably fix the issue.

Google search for sierra encoder motor sensor replacement. There's a good write up on the fullsizechevy forum.