1999 suburban 6.5 diesel stuck in 4 lo

[rac2016]

Alright I have a 99 suburban diesel that is stuck in 4lo(has the electronic shift) and we have done everything it seems like. So far we found that the TCCM was shorting I could wiggle and it would click. We replaced that. No more short, the switch on the dash was not lighting up and found that to have a short(which research shows is common). We replaced that. Now I would push, lets say 2hi it wold blink then revert back to 4hi or 4lo or whatever position it may be blinking in when I turn on key. Just would never go constant, plus never heard the encoder motor trying to shift. So I literally pulled the entire harness for the TCASE out and inspected it. Nothing out of the ordinary. put it in plugged it all back and replaced the encoder motor. Now I can hear the motor working but still will not shift. Did some research and found it could possibly be the actuator on the front diff. Figured already put a significant amount of time and money may as well replace that. Well it worked for about a whole 5 minutes, was able to switch every position on TCASE. And now its stuck in 4lo and I cant hear the encoder motor and or when I do hear it, it shifts into the position I select and then goes back to 4lo. Also has a new code c0305 (I believe)which was like front drive shaft speed sensor or something. That was an new sensor just a couple months ago and or Im looking at wrong sensor. But would that default to a 4lo position? I am at a total loss for this thing. everything is new now and still not working. Before its mentioned, yes I know the proper way how to shift in and out of 4lo. Thanks in advance for any pointers. By the way I've done OHMS test votage test the whole nine yards everything seems to check out. My next guess is honestly the TCASE internally being bad. Just crazy how it was working for about 5 minutes.

[VikingTrad3r]

get anywhere with this?

[dkjbama]

Transmission needs to be in neutral to shift into and out of 4-low. It sometimes helps if the truck is rolling ever so slightly, like slower than a slow walking pace.