M1151 w/4L80E wont shift

[hedcrash]

Newly purchased govt M1151 vehicle, purchased in non starting condition. I have the truck able to start now but the transmission wont shift. It is stuck in N and when I turn the truck on I cannot get it into HL, H, or L just Neutral. When I do try and shift it it is very hard to move and I feel a grinding sensation if I try and force it which I dont do. I have verified that fluid levels are correct, filter has been replaced along with gasket and everything looked visually ok. The transmission light is on when I turn the truck on and get it started. I am just wondering where I start to figure out why its not shifting at all. Thanks for any advice everyone.

 

[NDT]

We can help you. It is not clear to me from your narrative whether you are having transmission engagement or transfer case engagement issues. Can you elaborate? Two entirely different diagnostic paths.

 

[Mogman]

It would be very helpful if you would download and read the TMs provided here for free especially the -10 operator TM, One thing you will find is the vehicle transmission must be in neutral and the engine OFF to shift the transfer case.
Otherwise you can cause damage to the drive train.

 

[mrfarb]

Here’s a photo I made real quick. Red arrow is transfer case lever, never move that with engine on! Blue arrow is your transmission shift lever.

 

[hedcrash]

My apologies for lack of clarity and truly THANK YOU for all the replies above as it helps me learn, I am not afraid to admit I am learning. My issue is the transfer case it does not move. I have not removed the shifter yet but I did look under neath to make sure nothing is binding that i could tell and that the linkage was connected. I am aware of the manuals but wasnt sure exactly what I need to look at and being the 1151 most manuals didnt match exactly but I will be diving into them.

Now what I can tell you is that the transmission shift lever does move, but it feels loose to a degree like not quite engaging but seeing as I cant get the transfer case to move that could be an issue also just not sure as of yet. Now back to the transfer case...I gave it a pretty good shove up/down to see if i can get in another gear with truck off and no luck. Hope that provides some clarity, thanks all.

 

[NDT]

The transfer shift mechanism external to the transfer is about as simple as can be. If the pictured items are free to move, the problem is inside the transfer which is a bad thing. Time for more investigation.