My 2007 H3 Hummer has 30,000 kilometers on it. I was driving up a steep incline when the dash display alarm displayed "Serv 4WD" I checked the drivers manual and it stated the Transfer Case needed servicing. I am a licensed comercial truck mechanic so I serviced the auto transmission and transfer case. Two weeks after the service the warning display re-appeared. Is there a code that needs to be erased by the dealer? The oil was changed on the transfer case. Help!

 

I moved this for you................... because, this is NOT and FAQ. See https://www.hummerforums.com/forum/h...section-19461/

 

The Serv 4wd message is not tripped by fluid levels or need of fluid changes.

It can come on because of several possibilities, one of them being a Transfer Case Shift Actuator not working properly, another is your dash buttons for shifting the T Case may be stuck, and another if you have an early 07 or older, a bad plastic shift fork in the T Case....

 

Thanks for the information. Unit is booked into dealer next week to check for a stored fault code. I did check operation of 4wd in all modes;no issues found. 4wd does not get used very often;just winter season. I did shift into 4 high several times during driving this week;the "Serv 4WD" has not since come on. The vehicle still has two years left on power train warranty.