GM Repair Problems? Ask GM Repair Expert Now.
This is really common on these trucks. The most likely cause is a failed transfer case control module, but it could also be something as simple as a reprogram is needed. GM released a bulletin calling for a re-flash of the computer programming that controls the transfercase on this model in 2009. It's possible that the re-program was never done and now that some parts have worn a little it's starting to act up.
Do you plan to do any diagnosis/repairs yourself?
Absolutely. The only thing to be concerned about is that the 4wd won't work until you have the problem fixed. The truck should run normally in 2wd. We see these trucks with this problem all of the time.
Yes, the transfer case is just stuck in 2 high and will not be able to shift into any other gear unless it is shifted manually or with a compatible scan tool. Shifting it manually is nearly impossible without disassembling the transfer case encoder motor on this truck though.
No lights on the transfer case switch tells me that the problem is most likely a bad transfer case control module rather than a re-program issue.
A Chevy or GMC dealer should be able to take care of it. This truck uses all of the same parts as the silverado, sierra, yukon, tahoe, suburban so everything should be available and their computer scan tools will hook right up.
No, the service 4wd message is just alerting you that there is a problem. It's safe to drive, the 4wd just won't work.
This is the TSB I was referring to from GM:
That could be the issue, but it's most likely going to need a transfer case control module.
Please let me know if you need additional info.
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