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Discussion Starter · #1 ·
I've seen some other similar issues, but all include some kind of noise... I have a 2011 with manual transfer case(floor shifted.) Issue is sometimes it will work when I attempt to switch into 4hi or 4low, when it works dash lights normally, and it operates as it always has. Sometimes when I go to shift the lever feels normal but it wont engage at all, or I will have to give the lever a wiggle to engage, but often it wont engage at all. Could my issue just be that the linkage connector is worn? When I get under the truck and grab it I dont feel any play, but I have noticed the original part has been superseded by a newer part number in gm parts. Full disclosure, I haven't changed trans, transfer case, or diff fluids since about 90k miles and I'm at 150+/- k, about 10k overdue, could that be the issue? Any help is greatly appreciated!
 

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Some people change their drive train fluids often and some never change them at all. I typically go with 100,000 intervals unless I have a reason to do otherwise, like parking in a creek for a while until I can get unstuck. This also lines up with the GM normal service interval except I can't find a diff fluid service interval for your truck. If you look in the owner's manual it may advise fluid changes after every off road excursion. That's overkill. GM is just being overly cautious because they don't know what you have done in the boonies that might have contaminated the fluids.

I think your fluids are not the problem.

GM part numbers change for many reasons. Perhaps the supplier has changed so they will give it a new part number even though the part is close to identical to the old one. I've seen part numbers change several times with no discernible change in the part itself. Maybe there was an update but I wouldn't make too much out of the part number alone. Ask the parts man. He may know the reason for the change.

What can happen with a transfer case is that the internal parts that need to mesh to engage 4X4 will hit nose to nose so that they can't slip past each other to engage. When that happens it can help to wiggle things around but sometimes you just have to move the truck a bit so that the parts reorient.

It is also possible that something is broken but I tend to lean toward normal operating conditions. The shift between high and low range is best made in neutral with the truck rolling along slowly, like 2 mph.
 

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Discussion Starter · #3 ·
Appreciate the reply... Maybe my issue is I'm too a.r. about stopping and throwing it into neutral to engage 4x. I've never hesitated to release 4x and drop her into 2x after the 2-3 shift, but I'm not sure I've ever engaged in on the roll. I suppose I'm just old school and remember getting out to engage the lockers! I gave it a shot and seems like I just needed to ease up on the worries, seems to engage just fine slowly rolling in neutral.
 
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