Wont shift into 4wd

[Car-Dog]

Hey guys, I have an auto 4wd transmission and today when i got in my truck the 4wdhi and 4wdlow lights started flashing. they seemed to flash for a couple minutes and stop and start again and when i tried to shift it into 4wd nothing happened. If you guys have any ideas it would be great. thanks.

 

[BrooklynBay]

The sticky threads on the top of the transmission section have a lot of troubleshooting information.

 

[Car-Dog]

Thanks I am still pretty new to this forum and don't really know my way around yet.