I was wrong...
I was wrong: I thought I was looking closely, but not closely enough. The central lock module is stuck in a small space on the outboard side of the battery, partially hidden by the carpet, and is encased in sound-proofing foam which also conceals it completely.
I located a blown fuse to the central locking system, in the back/left corner of the engine compartment, in a box that houses mostly relays. I replaced it, but the central locking isn't working; in fact, the module isn't making a sound. However, now when I lock the driver's door with the key, I get a single, quick, relatively quiet "beep" from somewhere near the back of the car. I'm going to search for some troubleshooting procedures: I'll let you know what I find.
Last edited by PhilD; 07-27-2011 at 06:36 PM.