my message center on my 01 2500 gmc duramax flashes 4x4 out of self test range every once of a while for about a year when i first turn the key and just recently my transfer case wont lock in but i can hear the solinoid clicking, wondering if its a sensor ? Has anyone else seen or had this problem?

Moving to ''Drivetrain''...

so im guessing no one has had this problem?