I have a 1997 Chevy k1500 z71 4x4 and my truck will shift into 4 low and 4 hi but will not shift into 2 hi. It is a manual shift 4 wheel drive. The actuator is working. I've changed the front differential gear fluid and the back and the transfer case fluid and it still doesn't seem to want to kick into 2wd. I've reversed to try to kick it into 2wd and have just about done everything under the sun. Any suggestions?

 

Have you tried a "rolling" change ?

In 4hi, get rolling about 5 mph
shift into natural, then, press the 2 hi,
it may shift as you slow down.

IF you get it to change this way, don't stop with one shift.
Things can get sluggish from non-use, so shift it several times, and
run through the drives about once a month, just to keep things stirred up.

 

I've tried rolling and siding into 4 wd and reversing and turning sharply and parking on a hill and just about everything else asking with taking
everything apart and cleaning it. My next thought is that it has something to do with the hubs that are auto lock. Any suggestions there?