I'm posting this in case anyone else finds themselves in this situation.

I found myself yesterday with a full tank of wiper fluid, but it wasn't being sprayed on the windshield. The front headlights were getting sprayed and the wipers were working so I figured it was either a hose issue or a fuse issue. I didn't see any leaks on the hoses under the hood or under the car. The only fuses listed in the manual for windshield wipers are in the engine fuse compartment (#11 for headlight washers/pump, #17 for windshield wipers) and both were fine. The manual for the 2004.5 doesn't list any wiper fluid fuses in the passenger fuse box, but the 2005 S40 manual lists fuse 48 as being for the headlight washers (it is listed as not in use for the 2004.5 S40). However, changing that fuse fixed the issue and the pump for the windshield wiper fluid began working again.