Maybe not the most glamorous of fixes, but every bit of knowledge adds to the store. As you know, the exterior cargo/bed lamp is actuated by a pull-out switch located outside the cab on the upper right rear (when the parking brake is set, and the ignition keyswitch is set to ACC or ON). This switch is protected against water entry by a boot. This boot can be dislocated or cracked, and to prevent water entry and subsequent corrosion or failure, the boot must be reseated or replaced. The procedure is the same whether reseating or replacing. (I was able to get away with reseating.) Unscrew the switch knob from the switch body. If you have a dislocation issue, the boot's probably come loose from the hex nut on the switch, and therefore it will accompany the knob when removed. Remove the knob from the boot. Inspect the boot for cracks or tears. If ok, work the boot base back around the switch hex. I find that a small amount of ArmorAll acts as a lubricant on these boots. Clean the switch knob and carefully thread it back on the switch stem. Fine threads here. Snug up the knob. If your boot is original, again add a drop of ArmorAll to the knob/boot seam and work the boot back over the knob as before. What if you need parts? A quick search of Amayama did not give me a part number. Megazip.ru suggested it was the same boot as on the door pin switch (83443KA020), which isn't true: the boot base is the only hole in the door switch boot, whereas there are both base and tip openings on the cargo switch boot. I can see where you could mod a door switch boot to work on the cargo light switch - you could either punch a small hole to go over the threaded switch shaft, or cut a larger hole in the end of the boot like the OEM part (recommended). Or you can point out where I've missed the boat, and post a part number...
The boot on its own is part number 682156050, and is about $2. The entire switch, with the boot included, is part number 682156021 which is about $12. I did not originally add the boot to the spreadsheet, since the whole switch was only a few dollars more and included the whole assembly. If the boot was damaged in some way, I figured there was a good chance that the switch itself got water in it. That said, I added it a few minutes ago since you did ask about it. Your frustrations there with the Amayama and Megazip search is the same reason why I bought the original Japanese parts catalog software. They have an older snapshot of this catalog as the basis of their website, but they strip out a lot of the context that is provided in that software.
