Update: I accidentally knocked off the plastic cover for the fusible link in the fuse box that sits on top of the battery, exposing the fusible link itself. Will I be okay covering it with electrical tape or do I need to buy a new one? If so, what part should I be looking for? I don't know if the cover is replaceable, but I'm unlikely to find it anyway as it is probably in some unknown crevice. Update 2: Apparently it's the 120A main fuse. Googling the part turns up this thing which matches the photo from my car. I should just be able to buy a $5 120A straight fuse at Advance Auto Parts instead of the $20 Toyota part, right?
Yes that’s fine it’s just to protect anything from falling on the positve post. It probably fell behind the battery by the fender. It’s red actually. You can just drape a towel over it instead. Mines been off for quite a while. It gives you easy access to the battery wire plugs the thick black one is the main power lead to the front jump point. That’s how you pull the battery with no sparks. With those 2 leads disconnected the battery is completely disconnected from the car. You can unbolt the neg lead with no sparks. I see yours are all disconnected. Love West Wing.
I don't know whether you need to tape it, as long as you install the red cover. In any case I don't know I'd go to all the effort to buy and replace the existing fuse, assuming it still is functionally usable. I'd just wait until I can retrieve the lost cover, assuming it pinged off and down the side of the battery. Perhaps you could buy the cheap one and hope you can harvest the cover and attach it to the existing fuse.
Unfortunately, the cheap cover doesn't fit the OEM fuse. Worse still, when I went to remove the fuse, there doesn't seem to be an obvious way of taking apart the fuse block, if you're even supposed to. I think, at this point, it's probably good enough to find a thick piece of plastic and tape over the fuse with it before I break something else.
I bet you'll find there are ways the sides of that black structure unclip and swing open, giving you access to the little screws that secure the fuse legs on both sides. I included this picture in a write-up about my Gen 1 that shows one of the sides folded open and the fuse leg and screw visible. I can't quite tell whether your Gen 2 fuse block is just like the Gen 1 one (except for a different angle of the metal bracket to the terminal) or slightly different, but I bet they are similar in construction. -Chap