So I've been occasionally turning into my drive with the 07 H3 and it feels like for a moment the 4wd is locked and slows the truck down and while turning feels like steering wants to straighten out. Then it will go back to normal again after I back out of the drive. What I'm coming up with on numerous searches is probably got the plastic shift fork wearing out if I have it... I have the 2007 version with the window switches in the lower elbow position, apparently this is the early 2007 before the mid cycle changes. So I can't seem to find any info saying exactly when they started putting in the metal shift fork. I would think it would correspond to the mid cycle change, but I have not seen any confirmation of that. If anyone know the vin #'s or other way to tell differences between the transfer cases, I'd like to know. I saw something about a sticker saying you need to add oil through an extra filler hole on the old TC's but I don't know if that is the best way...

 

I'm thinking a whole lot of other stuff before shift fork. Jmho
Chris

 

sounds like a rerun of dozens of other fork problems to me

 

Now I just need to find out if it's plastic in there without tearing it down.

 

The TC Forks have one function (one is hi/low, the other lock), they shift the TC from Hi to Hi Lock, then Low Lock. Once the shift is done, they are not doing anything. So either you are in Hi, or you are in lock, you can't be half way in between or randomly one or the other without actually pushing the TC control button.

The fork problem, when it exists, will not allow the TC to shift between the options. I have the plastic fork with zero issues, and I will not be fixing that until it stops working.

So..... when you have a TC Fork issue, the TC will not shift. If it shifts = no fork issue. You may eventually notice that is may require more than one attempt to get the shift done.

#7 (PN19178136) is the Hi/Low shift, usually not an issue, #26 (PN19180438) is the lock shift, that one is the usual culprit and known as the "Plastic Fork".

 

at least your symptoms are very familiar, if you ever hear a loud bang it's the chain slipping in the TC, that would confirm it. The binding as you turn into a parking space is a tell in 4 high lock or 4 low you won't know anyhow with a broken shift fork. The encoder light shows 4 high as the cam on the the shifter swings back to normal 4 high but actually the TC remained in 4 high Lock because the plastic fork #19180436 never worked right in many H3s. For the average guy it might be difficult to determine if your TC is shifting properly, it stumped several mechanics for me before researching online. I found a Hummer Tech to replace the plastic part, he didn't need to ask me anymore questions. A Hummer Tech will know exactly what the problem is because they've personally replaced hundreds. Mine has worked perfect ever since, no binding or banging since. I don't recall a VIN# just the first 1/2 of 2007. No recall, GM would rather recall cheap switches, than their crappy soft valve seat engines or plastic in a TC.
Good luck, let us know what you find.

 

So Doc Olds seems to believe there is no way this is a shift fork problem...however many folks on here seem to have had the exact same issue that I am experiencing, and changing the shift fork out has solved the problem...so it has happened to me several times again in the past couple weeks. Turning appears normal and then all of the sudden in the parking lot or driveway entrance it has locked up and the tires are trying to jump as I turn. NO buttons have been pushed, NO lights are indication a 4hi or low lock. Back up turn the wheel some go forward again, and back to easy turning with no binding again....so if it ain't the shift fork, I want to know what other issues in the tranny usually lead to this behavior. If it keeps it up I think I will just change the fork out and see what happens..

 

I have no idea. I suggestion taking it to a mechanic that knows about transfer cases or just any old GM dealership around you... if no one on here can help you.

 

you should read what doc said. HE has no problem. then he described what happens with a busted fork. it sounds like yours is broke. he just gave info for you to consider. fix it b4 its more $$$.
its not a tranny issue.

 

I believe I did read the post and clearly the Doc is stating that if I have a busted shift fork then my tc would be stuck in 4hi or low and could not switch between the two. However, mine switches on it's own whenever it so chooses with no input from the driver. So his info concludes shift fork is not the problem. Once again, this is direct conflict with several owners who have had the exact problem as I, changed the worn or broken fork out, and have normal operation return to the tc. No disrespect to anyone, just pointing out the discrepancy with the info. Getting the case off of the truck and cracking it open looks like a lot of work, and I want to be sure it's the problem before I get in that deep.