Five problems related to transfer case have been reported for the 2003 GMC Sierra. The most recently reported issues are listed below.
The contact owns a 2003 GMC Sierra. While the contact was examining his vehicle he noticed that there was oil dripping from the transfer case under the vehicle. The vehicle was taken to the dealer where the contact was informed that a cover should be put on the transfer case to stop the leaking. The vehicle was serviced by the dealer and there were no prior warnings. The current and failure mileages were 76000.
4 wheel drive transmission will shift from 2 wheel to 4 wheel low while driving. Sometimes it will shift to neutral. This can be very dangerous. You basically don't have the control of the vehicle that you thought you had.
I have been having trouble with my four wheel drive. The engine seems to bog down like I am pulling something. Took it in to get looked at and the repairman had to replace a part saying that it was automatically kicking in and out. He fixed it and it was fine for about 6 months and now it is doing it again. You can even hear it in the engine, it sounds like it down shifts to pull something.
I have a 2003 GMC Sierra slt ext. Cab z71 (4x4), the 4-wheel drive is not working, no lights show up on the buttons. The dealer has attempted to replace the 4wd switch, this did not fix the problem, they still have the truck. The truck is less than a year old and has 20,700mi. There are service bullitens for the problem, but there is no permanent fix. Why sell a 4wd product if the 4wd will not work?.
When the 4 wheel drive light illuminates on the dashboard vehicle fails to accelerate. This is caused by the transfer case encoder motor locking in 4 wheel drive. Dealership replaced the part, but cause of the failure is undetermined.