Need help with transfer case problem....

[MidnightH3]

Hello, I'm a new member here and just got an 07 H3 auto with the adventure package last Tuesday. Last night I was testing out the different 4x4 modes in a dirt field, when a problem came up. The transfer case shifted fine from 4 hi unlocked to 4 hi locked to 4 lo locked, then back through until it got to 4 hi unlocked. When it tried to shift back to 4 hi locked, it started making a grinding noise like someone who can't drive a manual. It would shift back into 4 hi locked and 4 lo locked just fine, but every time I try 4 hi unlocked, it makes that terrible grinding noise. I had to limp it home in 4 hi locked, but I kept it under 40 and kept the turning to a minimum. It has a 3 month warranty through the dealer I bought it from that covers the transfer case, but I wanted to ask here before I took it down there. I searched the forums and came across the TSB 3424 about the transfer case not completing shift but I haven't found what the bulletin actually says. So any ideas or help from anyone would be greatly appreciated, thanks!

[pdsq99f4]

Take it to the dealer. Sounds like the t-case has an internal fault or possibly a bad encoder motor. Does the 4hi unlocked light just flash or does it think it went into unlock and just light up?

[MidnightH3]

It thinks it went into unlock as the light stays solid. Thats when the grinding noise starts, like the gears are skipping off of each other and its not really in gear. Even in 4 hi locked I can hear something bad going on in there, like its not totally in gear. I dropped it off last night at the dealer, but I wanted to get some opinions here so I know if they try to BS me about whats wrong. Thanks for the help!

[pdsq99f4]

It's internal then. My guess is something with the lockup shift fork/collar assembly.

[MidnightH3]

I read somewhere that GM was using plastic shift forks in the transfer cases? I thought that might be part of it. Seems silly to me to use plastic inside a part that takes so much abuse. I'm waiting to hear from the dealer as to what their verdict is, thanks again for the input.

[HUMTECH]

Electronic transfer case may stop shifting if you repeatedly try to shift the transfer case in a short period of time and not set any dtcs
<A href="http://gsi.xw.gm.com/si/showDoc.do?docSyskey=1861186&from=sm#ss2-1861186">Recommendation/Instructions:

The software in the transfer case control module has a "shift abuse lock out" mode to protect the module and encoder motor. This concern will occur if the module senses repeated shift request in a short period of time. If the driver continuously tries to shift in and out of different modes, the transfer case control module will stop trying to shift for several seconds to prevent abuse damage to occur. Cycling the ignition off for 30 seconds or more should allow the transfer case to resume normal operation.
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.