The 4WD transfer case encoder motor position sensor or the selector switch may fail causing the service 4WD message to be displayed. Fault code(s) stored in the transfer case control module will be of assistance in determining the exact fault causing the message to be displayed.
Service 4WD Message May be Displayed on Chevrolet Silverado 2500
Average mileage: 111,416 (68,000–220,000)
Drive Trains affected: 4WD, Automatic Transmission
13 people reported this problem
2004 Chevrolet Silverado 2500 - 4WD 70,000 mi, Visitor
my truck is a 2008 model it will not shift into 4 wheel drive and the light is flashing. the 4 wheel drive has rarely been used.
Still have the problem, needs fixed, just took the driveshaft off
2000 Chevrolet Silverado 2500 - 4WD 70,500 mi, Visitor
Service 4 WD light comes on but it drives fine and Transmission was serviced
1999 Chevrolet Silverado 2500 - 4WD 132,000 mi, Visitor
I have a 2008. Light just came on.
replaced switch...light first came on at 100,000 miles.