There are a number of reasons why your door might not lock. You could have something stuck in the door for example.
The answer is a key
probably because the door lock actuator for that door is faulty. i would test the actuator first.
remove inner door panel for access to lock
Digital door lock would do that.
The power locks can only be engaged from the driver's door. You press down on the door lock on the driver's door and it will lock all the doors. Or you turn the key in the lock to the right in the door lock of the driver's door and it will lock all of the doors.
Slide the card through the slot where the lock is by the door. Set the card where the lock would be. Now open the door.
You will have to remove the door panel. And it will be mounted over by the door lock on the inside of the door.
What? Barn door lock on a Yukon????
Take out the "Door lock fuse".
Begin by removing the inside door panel on your 1997 Plymouth Grand Voyager. Remove the door lock linkage. Remove the door lock retaining bolts. The door lock will come out.
Hold door handle (opening lever) as if you're opening the door and then push lock lever to lock