I would also suspect the signal arm being the problem. You have 4 harnesses to it, and they tend to burn out and it seems the one that quit is the wiper controls. I'd suggest taking the signal arm completely off of the column and check the condition of the harnesses. If you see any blackened wires, melted plastic, or smell anything, it needs to be replaced. Just because you don't see anything doesn't mean there's nothing wrong either. They usually go out about this time, meaning their age. Mine's an 88 and it needed replacing, no way around it. If a harness needs replacing, your Ford dealer parts counter carries the pigtails, this is very common. But where you're having wiper trouble, my lights were my trouble. They'd wink off and I'd be driving in the dark... lots of fun. I bet that's your problem because you say they only work when you put them on high. The position of the wipers doesn't have anything to do with the proper operation or not operating until they're switched to high.
You take the wiper arms off by using some needle nose pliers and you'll see a small tab on the top side. You pull those out slightly, then pry the arm upwards off of the shaft. But again, that isn't your problem. That turn signal arm needs replacing. They usually run around $100-$110 and it's only 2 bolts, 4 wiring harnesses and 15 minutes of your time.
AFM Site Administrator
Member: Mustang Club of America #82740, White Mustang Registry #362, NMRA, Fun Ford Weekend, Mustangs of Burlington
MOOG Certified Technician
For mods and sound clips, see profile and gallery.