Hello, I have a 2007 GMC sierra SLE new style body 5.3L z71 crew cab. The ABS and traction control lights came on about 6 months ago, and at that time and I was able to determine that the left front wheel bearing was faulty. I decided to change both front wheel bearings, and the ABS and traction control issue was fixed. The traction control light and ABS lights have come back on. I have bad drag when I turn either left or right now to the point where the back tires spin. I had the vehicle 4 wheel drive in auto mode. I read that the vehicle is in auto mode until the vehicle reaches a certain speed. I doubt the issue is the wheel bearings again cause there is no noise like before. My buddy told me to turn the vehicle from auto mode to just 2 wheel drive so when I did the drag disappeared and the vehicle turns with ease now. My problem is that when I trun it back to auto or 4x4 mode the drag comes back when I turn left or right. Any ideas as to what the problem might be? I do have some mechanical background, I am guessing either the front drive drain and or the electric shift motor in the front drive train. I would like to know if I could change it myself if its just the electric motor. thank you in advance for the information.