Possible transfer case issue........

[Bigunit]

Did you replace the plastic shift fork with an aluminum one?

 

[jakesz28]

Yes. Moved to other thread.

 

[650Hawk]

Manual says only shift between 4 Hi & 4 Hi Lock below 45mph. Mine WON'T shift at anything higher than that; it just blinks for awhile and then reverts back to the original setting. Below 45mph, it blinks for about 5 seconds and then changes over.