My 2002 cummins auto wouldn't shift. I replaced governor pressure sensor and solenoid. Now it shifts fine but won't shift into overdrive. I also replaced the output speed sensor. What is the reason for this? I don't have any codes at this time.

 

Try resetting the APPS. Remove both Neg Battery cables and let it set for 30 mins.

Hook the batterys back up and turn the key to the on position without cranking the starter, then turn it off. Turn it back on, off and then leave in the on position the third time. Push pedal slowly to the floor and then let it slowly back up, turn key off.

Now start the engine and see if that helped. This will reset the pedal position sensor.

That is without cranking starter on-off-on-off-on.