One last question.
I am just GUESSING that the PWU works in such a way as to prevent activating it immediately when you lock the truck and walk away. I.e. if you lock it by pressing the button on the door and start to walk away, you are still close to the truck. But, in that case, you wouldn't want PWU to immediately turn on the greeting lights and extend the power running boards.
So, my guess is that after you lock it, it waits until it detects that the key fob has "left the building" (so to speak). THEN, after the key fob has gone away, it will reset itself internally such that PWU will activate when the key fob comes back.
On that theory, the question is: Have you tested PWU where you are confident that the key fob has gone "out of range" of the truck after you locked it?