I had a little trouble figuring out the exact procedure to remove the door panel on my 2002 Avalon so I thought I would post a brief how to for the benefit of others.
First, remove the screws. There are 3 along the bottom edge, one behind the door handle (covered by a hinged cover) and two on the inside toward the dash (covered by caps which just pop off).
Second, remove the triangular sail panel. It is attached by a metal clip which just slides off and a protruding pin which an indentation slides over. It is harder to explain than it is to get it off. Basically, just pull out and away with gentle force.
Third, remove the door handle cover. This is the trickiest part only because you can't see the pins and it isn't obvious what to do. Stick a thin flathead screwdriver in the space above and below the lock button and between the the handle cover. You can find a picture with an arrow showing the spot here:
http://autorepair.about.com/library/.../aa092504b.htm
Fourth, remove the the window button panel. There is a clip at the rear you can pop loose with a screwdriver. Lift up and back as there is a plastic ledge in the front which goes under the door panel.
Fifth, disconnect the wires on the button panel.
Sixth, in the opening for the button panel you'll see a large screw that needs to be removed.
The panel should lift right off. Installation is the reverse. I am doing this from memory so forgive me if I missed something.
On to my question: the passenger side door unlocks with the button/fob but doesn't lock. The mechanism works manually and with the key. It does not appear to be binding. What might be the cause?