pretty much.

 

What happens when one goes out like a fuse would?
Can they be replaced with a regular fuse?

 

They're very easy to diagnose: pull. If the insulation stretches, the wire inside is burned. Read this caption:



The bottom of this one shows what some of them are for:

 

1991 f150 found horn relay behind glove box, fuse should be in the power distribution panel, can not find such a thing under hood. Where is the horn fuse, it is not in the fuse panel by the steering colum under the dash