I have an 88 F-250 with some similar issues. Has anyone experienced a total loss of wipers? I, too, experienced the "no low or intermittent, but had high". Then last week, the high completely stopped working. I replaced the switch and now the relay box just clicks and clicks when I turn on the wipers, but no wiper movement? Any help?

 

When the wiper switch is in HI, 12 volts from the wiper switch goes directly to the wiper motor circuit 56 a Dark Blue/Orange wire. The ground for the motor is Circuit 57 Black wire.

 

did you replace both the switch and delay module, or just the switch.? if just the switch was replaced, try replacing the delay module also.
whenever i have wiper problems, i first replace the delay module, and 99% of the time that fixes it.