Well, after tearing into my 2004 Sienna XLE's left sliding door I can assure you that there IS a Lock actuator in it. It's just that Toyota does not stock the individual part. In order to get it you have to buy the whole metal panel assembly to which the lock actuator (for which Toyota has no part number ???) is attached by two screws. If you can no longer lock and unlock the door other than manually, you may be a candidate for this economical repair. Using one of the many YouTube videos showing how to take the door apart and get at the various actuators and mechanics of the door, remove the lock actuator and split the shell, if you're lucky, remove the dead motor inside it, and replace the dead motor with one I happened to find on eBay. It's listed as "FC-280 Motor with Collar - Car Door Lock and Mirror Motor - Auto FC-280PT-22125" and is sold by "mopselectric" on eBay. It fits the worm gear in the actuator and works perfectly in my formerly-dead lock actuator. Instead of having to buy the whole $800 or so panel, I spent $7.65. My lock actuator (NOT the door actuator) had a motor with a brass bushing on it to drive the worm gear to flip the lock back and forth and lock/unlock the door.CE, LE, XLE, or XLE limited?
From what I can tell, there's no lock actuator in the sliding door. Maybe I missed it.