My bronco will not go into 4x4. I thought it my be my transfer case shift motor, but I changed it and it still is out. It has since gotten a vibration that feels like it is coming directly under my driver's floorboard. A mechanical told me to take the front driveshaft off and try that. It's still there. He then suggested the transfer case itself. I don't know. I am new to working on my own vehicle and am trying to save money by fixing it myself...ANY HELP? I also changed my transfer case computer under my passenger side kick panel, and the 4x4 still don't work???