I'm new to this site, and lost as far as where to post my concern to see if others have experienced it or have suggestions. My new truck with 7,000 mi. has had the SERVICE - 4 WHEEL DRIVE light come on twice now! First time I took it in to fix - they "rebooted" it. Happened again today. The full story is HERE: http://blog.timesunion.com/farmlife/2807/gmc-sierra-serious-dismay/
Feel free to comment there because I'm not sure I'll ever be able to find my way back here! But, I'll try.
Thank you.

find a different dealer.

What they meant by "rebooting" it, is they probably just disconnected the batteries and waited 5 minutes. You can update the software in the TCSM (4wd computer), but there is no ""rebooting"" procedure.

If it said service 4wd in the driver info center there will be a code stored in the module's history. The dealer was probably stupid and disconnected the batteries (or "rebooted" it, as they said), thus clearing the code and destroying all evidence of what the problem was.

What the dealer needs to do, is next time it says service 4wd, they need to check the DTC history and see what exact code is stored, and then use SI (their service manual that basically spells out in crayon how to diagnose problems) and go through the proper diagnosis that way.......and not just reset the darn thing hoping it "fixes itself". ;)

ben

Ben,
Thanks for the reply. This information is great for me to have....especially now that I have to take it in again. There is another dealer nearby, it's time to check them out. GMC treated me like it was the most normal thing in the world to happen. Aaargh.
Again, thank you!

Ben,
Thanks for the reply. This information is great for me to have....especially now that I have to take it in again. There is another dealer nearby, it's time to check them out. GMC treated me like it was the most normal thing in the world to happen. Aaargh.
Again, thank you!

Teri next time it happens, find a different dealer and see if you can get them to give you the code number...that will be able to help out as to what the exact problem is.

It will most likely be a "Cxxxx" code, where the x's are a series of numbers. However it could also be a "Uxxxx" code also...

Also, just out of curiosity...your transfer case and front differential has sufficient fluid in them right? Also if you have a garage to pull your truck into, see if you can crawl underneath and check for any obvious looks connectors. There will be one connector on the front axle (offset to the passenger side, a little plastic round module about the size of a soda can, that will have a plug/wire going to it), and another connector on the transfer case itself...

hope that helps

Ben