Fuses and other confusing truck parts

The truck didn't really break down, but the fuse broke and we had to stop and get a new relay, fuse and horn, I know what a horn is, the other two, no clue.
Pito wanted to help a bit, so he is holding the #20 fuse. Which I found out is housed in the #5 section of the truck.
I still don't know what I am talking about =)

We enjoyed Apple soda while we waited however, and that was downright yummy!!!