My 925 5-ton 6x6 will not shift into high range

[alabamafrog]

I finally bought some batteries for my new to me M925 cargo truck. However, now I need to figure out how to get it to shift into high range. When I picked it up at DRMO it would only drive in low range. The batteries were disconnected and DRMO jumped it off and screwed in the manual fuel valve to keep it running with no power. We figured out it would work in Low or Neutral but when we shifted into high it would not move and made a very faint grinding sound. It was very hard to shift, I tried rolling and sitting still in both Neutral and drive, to shift I had to jerk and/or shove very hard on the handle with both hands. I checked the linkages underneath and it appears like the shaft coming out of the T-case is moving all the way in so I figure it has to be something internal. Driving floor boarded at 20 mph in a 65mph zone sucks bad!
Question 1, is this a known or common condition?
Question 2, whats yalls best guess as to what to do next?
Question 3, how do I get it to go into high range and stay there so I can drive it the rest of the way home?

 

[Bolkbich]

try this link M939 series transfer case low range / front axle engagement

 

[Bolkbich]

this too M939 transfer case air lines installed wrong

 

[Bolkbich]

with no power to the dump valve for the t-case shift shaft lock and full air pressure you cant shift the t-case

 

[alabamafrog]

try this link M939 series transfer case low range / front axle engagement

I found this one while searching for info before posting my question, but I didn't see anything about shifting into high and grinding like mine is doing.

this too M939 transfer case air lines installed wrong

This one was interesting, I will look into the air lines and the front axle engagement.

with no power to the dump valve for the t-case shift shaft lock and full air pressure you cant shift the t-case

I was wondering about that little button, with the big warning sign to use it when shifting, and the wires going to it as opposed to having no electrical power. However the shifting shaft seems to be going in and out like it should, what does the shift lock actually lock? could it be as simple as when I put batteries in it then the button will work and she will then shift into high? am I that lucky? But then again it shifted into low and neutral and felt like it was going into high. I wonder if the guy stomping the shifter down into high without the lock button working may have damaged something inside the T case, and if so then what? When I got the truck it was parked with the T case in neutral with the brakes jacked open because one of the gladhands was broken off.

 

[pctrans]

I think you have a combination of issues going on. The air plunger on the t-case may be corroded, not allowing the gear to engage properly. Also, DO NOT use reverse in low range!!

 

[Bolkbich]

You might have to let the truck roll a little bit when your trying to get it into high, trans always in neutral. Make sure your shift linkage and pivot shaft are nice and free. Make sure there is no air to the piston on top of the t-case (shaft lock ). They can be cranky but they always shift for me eventually. I have had them grind like your saying , but for it to grind your either in gear (trans) or rolling.

 

[alabamafrog]

I am now certain the problem must be internal. I have bleed the air off and it did shift much easier, I also put batts in it and now the button works and it shifts fairly easy. It feels like it is shifting through the 3 different positions as it should however when all the way down in high it will not move, I can barely hear gear noise when I shift from forward to revers but no movement. I took the linkages apart and adjusted it out some but that only makes the shifter handle stop up a little higher. I'm having trouble finding a good exploded view and/or identifying what might be the problem.

 

[alabamafrog]

Found and fixed the problem, turns out it was stripped gear teeth inside the T-case. I paid a local mechanic to remove and disassemble the transfer case and he found the teeth stripped on the high low shifter gear thingy pictured below. He flipped the assembly over and cleaned up the edge of the teeth on the high side gear and put it back together. Now it has high but not low which is fine with me. I can run 55mph down the highway now so I'm happy. There were no parts costs except for new gear dope but he charged me $700 for labor. I should have done it myself but I just don't have the time or facilities right now to work in.
Hopefully someone else may be able to get some help from this post.

 

[wsucougarx]

Yikes, I am now grateful that mine was just misconnected wires.