My truck went into tranny limp " shift inhibited" mode Code was P0708. While driving, at speeds under 1 or 2 mph the tranny would drop into park. The shift inhibited rest to n would light and would reset if shifted to neutral and key cycled on and off. Was able to drive it home by clearing the code and then putting in manual mode. Quick shift to n at stops and roll thru. Can't do that again! Question is TCM, internal mode switch? Replace one or both? I live in a small town about 70 miles,from the nearest dealer and at least that far from a tranny shop. Do I have to have a tech 2 to diagnose or,set into fast learn? Any advise is greatly appreciated.