i have a 96 blazer 4.3 4x4. up till two weeks ago everything was fine but now i cant get it to go into 4HI. i can only press 4HI in neutral now and it will flash at me and kick me back to 2HI.. it shifts into 4LO just fine. i tried 3 different shift motors and they all do the same. i can hold the motor in my hand and if you press 4HI it is almost like the shift motor jams, but i can shift my transfer case with a wrench into all gears with no problem.. does anyone have any idea what could be wrong? i live in ontario, canada and i now own a blazer that is allergic to snow.. thanks for your help in advance.. ps... i checked out the obd2 non auto transfer cas diagnostics and it kinda sounds like what mine is doing but i dont quite understand it

 

See if this helps at all.
https://blazerforum.com/m_52228/tm.htm