2006 H3, won't shift into 4H or 4L. AWD working.

2006 H3 won't shift into 4H or 4L, AWD works. Light on dash flashes for a few seconds is all. Any common issues? Thanks!

Can be a couple of different things but most likely is the shift fork inside the transfer case - this part is known to wear out. Could be a bad encoder motor (the motor that actually connects to the case to change shift modes) but that's less likely. Could be sticking buttons on the dash, that when you press 4 Low the 4 high unlock button does not release.

Glennc6 said:

2006 H3 won't shift into 4H or 4L, AWD works. Light on dash flashes for a few seconds is all. Any common issues? Thanks!

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Do you mean it’s in 4H, but won’t go to 4H lock and 4L lock? If so, I’d suspect the actuator motor thing before the shift fork. The fork that breaks is for lock and unlock, not high or low range. If the fork was broken it would still go to low range. Unless that one is broken too, but it’s metal already so I doubt that.


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06s and maybe most years came with plastic shift forks.

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Help me understand this. If the fork only controls locking, and the other two modes involve locking, And it won't go into those two modes, how come it can't be the shift fork? I agree that it could be the actuator but I don't think they shift work can be ruled out

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Some info from an old fart I used to know in regard to the years for the plastic shift fork....
https://www.hummer4x4offroad.com/fo...ow-do-I-know-if-I-have-the-plastic-shift-fork

If the vehicle was off-roaded or driven on dirty/dusty roads a lot, I would look carefully at the switches. Make sure one of them does not appear to be still pressed when trying to press in another button cause this confuses the poor little computer. You can also use a sharp knife (something I used quite a few times when in Moab), place under each switch and press against the switch and pull back and do it to all switches to guarantee they are all out of contact with the circuit board. Then try to change position by pressing in the correct switch. If that works, your switches are dirty and sticking and very easy to clean. If not, head down under the vehicle and do some further troubleshooting.

f5moab said:

Some info from an old fart I used to know in regard to the years for the plastic shift fork....

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Sometimes those old farts know there stuff. Almost like they worked on the H3 for GM.

Thanks for sharing that link. I had not seen that. Very interesting.

alrock said:

Help me understand this. If the fork only controls locking, and the other two modes involve locking, And it won't go into those two modes, how come it can't be the shift fork? I agree that it could be the actuator but I don't think they shift work can be ruled out

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Click to expand...

There are two different shift forks. The lock/unlock and the high/low. If the lock/unlock is broken that wouldn't prevent the transfer case from going into low since the other fork does that. When my lock/unlock fork was broken, it was mostly stuck in locked mode. I could still switch to 4 low lock with no problem though. The buttons/lights worked like normal, but even though 4 high was selected it was actually in 4 high lock most of the time so it was breaking CVs. Since OPs issue is the lights flash with nothing happening I don't believe it's the fork.

Did I read somewhere there was a metal shift fork available at one time (but may not be available anymore)? Anyone have a part number?

A company called Dorman (or Dormain) out of Canada used to make one, might still be available; not sure. Probably others too. In fact under warranty in later years, GM was replacing with a metal fork.

Regardless of what anyone thinks there is technically a correct way and an incorrect way to diagnose. Start with the easiest and work down under the vehicle. Don't want to drop a TC just to find out it isn't the fork.

If I was the OP, first thing I would do is get a GM dealer to run a complete GM service document on the vehicle and see if it was replaced under warranty. Like the front axle if the person had a parking lot queen, the fork would never break or melt (similar to the frt axle never failing). Then you need to ask what the previous owner did with the vehicle (might be totally impossible but you never know).
Then go look at the switches like I noted.
Be a bummer to tear the TC apart and find out it is a steel fork....not so bad if plastic and you then replace with a metal fork.

Just giving some ideas....

Read my signature for further info....:giggle:

Here's what I used. Can't beat the price.

https://www.amazon.com/Dorman-600-6...?keywords=h3+shift+fork&qid=1573837553&sr=8-1

Thank you! Might be worth getting ahold of while they're still avail.

If needed, here is an old link on how to clean switches....
https://www.hummer4x4offroad.com/forum/showthread.php/87-Serv-4wd?highlight=buttons