Problems with switching drive mode

[Tina Klanac]

Hello! I have a bit of a problem and i would be so grateful if someone could help me.
I own Hummer H3, 2006 and the problem is:
when I try to shift between different all-wheel drive modes the light on switch buttons flashes but then it doesn`t remain lit. I did everything that is recommended in owner manuals. Previous owner told me that he never tried to switch the buttons so he basicaly never used it.

Can someone please tell me what is going on?

Thanks

 

[4speedfunk]

Most likely the buttons on the dashboard are dirty and sticking. This is a very common issue. Try scrubbing the cracks between the buttons with a soft toothbrush, and cycling through the modes once in awhile, to keep dust & dirt from accumulating in between them. You can pull the switch assembly entirely if need be, to clean it. Takes about a half-hour. Also, I find that it helps if you put the transmission into Neutral when shifting modes, and it seems to work best if you are rolling very slowly (5mph). Having things spinning slightly seem to help the t-case change modes. Try the toothbrush thing first. If that yields no improvement, then it may be something else (encoder motor or shift-fork).

 

[Neo]

most likely sticky buttons like Funk said. you can try pulling the one sticky button out with your fingernails when you know which one is sticking and that will let the other engage.

 

[Tina Klanac]

Thanks to both of you, i`ll try to clean them and hopefully that will fix the problem

 

[Tina Klanac]

I cleaned the buttons and still nothing has changed. Any other suggestions what it could be?

 

[4speedfunk]

Hmmm. That complicates things somewhat. I assume the vehicle is okay and it is stuck in 4HI-Street mode? Also you have no "service 4wd system" warning lights, correct?

If so, You might want to shift your efforts (no pun) to the mechanism that physically does the work. There is a small actuator on the outside of the t-case that controls the shifting. It's bolted on with 3 small bolts. You can pull that off and have someone switch modes while you look at the working end of it. It should rotate as you cycle the modes. This motor mates up to a shift fork inside the t-case....and that's what actually changes modes. H3's are famous for having problems with this fork. Early ones like yours have a plastic shift fork and they break inside the t-case. If the encoder motor is working...it's probably a broken shift fork. You can get a metal one to replace it. It's only $25 but it's a $300 job to install it.

While you have the encoder motor off...you can shift modes by using a pair of pliers but, only if the fork is good. If you try to shift it manually...you should feel definite "clicks" at each mode. If the fork feels jammed or spins freely...it's probably broke.


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