You may have to climb in back and remove the inderior trim panel and work the cable lever on the latch at the bottom of the door.....if it is caused by the door open handle.
If it is the lock....then you will need to move the lock ROD that goes from the lock cylinder down to the latch.
I had to bend the lock rod to "adjust" it back to where it works perfectly.
The door handle (part that you pull above the license plate) has a part that goes through the door and catches another lever that is spring loaded and turns......the handle pushing 1 side and the other moves up and pulls on the cable.
The part that sticks through the door is known for breaking.....the original handle being made of plastic.
The new ones that they sell now are made out of metal and much less likely to break.
Another thing that happened to mine was that the part that swivels......that I mentioned that the handle pushes 1 side and the other end pulls the cable......mine rusted so that it would stick.
The new handle assembly from TOYOTA includes both parts....mounted by 2 screws (hopefully not rusted).
Here is a picture of the part......which is mounted to the License plate light assembly.
I bought a new license plate light assembly.....and the handle came with it.
If you buy the license plate light assembly online (cheaper), then make SURE to enter your VIN (Vehicle Identification Number) in the order process as requested, and it will list the part that is the correct color for your van.
The first view is as viewed from outside, and the arrow points to the part that passes through to the inside.
The second view is as viewd from the inside and the arrow indicates the part of the handle that passes in from the arrow in the previous picture.
That end of the handle projection moves DOWN when you squeeze the handle....pushing the black metal part down....which swivels on the bright silver knob....and the other end of the black part moves UP....pulling the cable which pulls a lever on the latch at the bottom of the door.
To remove the trim panel....you need to remove the pull strap and the handle.....bolt/screws under plastic tabs.....then you need to pull the trim panel from the bottom to pull it out of the clips.
Then you will be able to see the latch.
Kind of hard to see, particularly when you are hunched over in the cargo area inside the van with the hatch closed, which is why I took pictures of the latch outside the vehicle.