I believe this is calibrating the enable valve in the control valve assy on top of the transmission,this valve is located in the port that has a number 5 cast into it the one with the number two is the forward soileniod valve and the one with number one is the reverse.
The enable valve,is actuated by a pressure switch on the bottom of the master cylinder,this switch sends a signal to the ECM which in turns energizes the enable solenoid,can check this pressure switch in the master cylinder,might not be functioning....