Service 4 wheel drive light - 2004 Chevrolet Silverado

You'll need someone to hook up with a good scan tool and read the transfer case service codes to see what is actually wrong. I do see a lot of bad Encoder Motor Position Sensors and bad encoder motors so that's my initial thought on what might be wrong but once the code is known the true problem can be figured out with a bit of testing. The sensor isn't very expensive but the motor is. Either one requires the removal of the Encoder assembly from the transfer case for service. Hope this helps and good luck!