I have a 00 blazer with 200, 000.....when I engage 4wd it switches and drives.....just recently after I switch back to 2hi the service 4wd light comes on...I've it on a tech2 to check codes and all I get is speed sensors codes....i put it on a lift to check it out and.I noticed today that the drivers side tire doesn't spin easily....also that the bearing on the passenger side is grinding....will bad hubs trigger a service 4wd light...also noticed it doesn't always switch back to 2 hi without tapping on the tccm