I have having issues with 4wd no one can figure out. I have replaced the front axle actuator,transfer case motor and new selector switch. I have no codes in it and I have service 4wd flashing. I had a guy to put a scanner on it and he can control and hear everything shifting but it will not allow him to relearn procedure. We have did it also from the switch put in 2hi then shift truck into neural then turn the selector switch passed 4low and hold for 40 sec and we hear nothing. He said tccm had the program already on it. I am lost to what is next. I have a new tccm to put on but waiting till the end because of the high price dealer wants. Any advice would be helpful. Thanks !