It's located on page 38 of the wiring diagram, which makes it look like it's beneath the center of the trunk lid, i.e., probably right at the lid latch strike. -Chap
The trunk light is integrated into the trunk latch below the lower plastic trim. As the latch closes it opens the voltage to the trunk light. An easy way to tell if it's working is to lay a video camera in the trunk and shut it. If it's working... you'll know when you see the video. That's how I found mine was jammed on all the time and draining the battery if the car didn't move for a couple of days.
