I was stuck in the mud and recovered over the weekend, 4x4 worked great including the low range. When I finished getting unstuck and parked the truck, I selected 2HI and the light flashed, and went solid immediately. I didn’t use 4HI again until I got home. When I press 4HI the passenger side of the dash clicks, I hear something happening underneath the truck, but the light keeps flashing and does not stop. It does the same for 4LO. When I select 2HI it flashes, then sets solid. When I set auto AWD the button flashes. In 2HI with a solid light, the truck is still in 4x4. In 4HI the light flashes, remains flashing with functional 4x4. In 4LO the light flashes, remains flashing with functional 4x4 low range.

 

Crawl under the vehicle and find the shifter arm on the side of the transfer case to make sure there is nothing blocking its movement. It sounds as though the motor is working but is not able to shift the transfer case.

 

Looked under the truck, found tons of mud I removed that was not blocking any arms it looked like, a vacuum line that was melted by the exhaust - cut the burnt part out and placed a barb, checked the hose to the vacuum switch near the firewall in the middle, and behold it was disconnected. Reconnected and everything is functioning correctly.