The Service 4WD warning has is being displayed from time to time. The dealership said I needed to replace thetransfer case encoder motor...$ 659.28 at Wyatt Johnson GMC Clarksville. Does this sound like the reason for the display? 64,000 Mi. 4 Wd never serviced. was told that changing transfer case lubricants would not make adifference.
Service 4 WD Warning on 2005 Chevrolet Silverado 1500
by popo63 in Clarksville, TN on July 13, 2009
ANSWER by ProChevy , July 13, 2009
This is really hard to answer without knowing the failure code in the system. There have been several service bulletins addressing the 4WD light coming on in these trucks. I'm sure the dealer has of course already diagnosed the code and is in the best position to tell you what code they found and why. The encoder motors do fail, and it might very well be the culprit. Changing the fluid probably would do nothing for this. Wish I could tell you more.
ANSWER by Oakman , January 14, 2010
We just added this article last week, hopefully it will help you with your 4wd issue: http://repairpal.com/gm-4wd-warning-light-issues