Are you talking about the 40amp AM1 fusible link in the fusebox next to the battery? There's a lot of stuff that branches off of that circuit so it may take a while to isolate the problem unless you can think of a more precise thing that you did or that happened just before it blew. For example, did you use your rear window defroster, was your AC running, did your headlights dim slightly before the fuse blew, etc.
