when this happend to me i had already disconnected the foot switch wires and taped each one off sepratley, and my wipers worked fine then one day they stoped working so i was like sh$t and i looked for every thing i thought it could be, i turned out that it was the fuse, all my fuses are those ceramic type ones not the glass, although one had been replaced with a small glass type one, this happend to be the fuse that ran the wiper motor when i took a quick glance it looked like the fuse was ok but i finally was like cant hurt to try the fuse so i pull it out and the fuse is blown so i go grab anthor fuse and stick it in and boom the wipers work perfect. just one thing to check.