It sounds like something in the wiring harness or it may be some naked wires touching and shorting out. Look for burn section of wiring around the battery or fuse area. It sounds like you have burned out a fusible link. This can be replaced by some one with a little wiring knowledge.
Have you checked the fuses for the wipers? It may be that simple.
MOTOR FOR WIPERS
I am wondering the same thing in 1994 safari van, have only wipers on high, i've unplugged the plug at the wiper motor & checked for power, only have power to wipers on high, now is the switch in the column with the signals,
Windshield wipers don't work
Windshield wipers and I think blinkers (turn signals)
Why are there windshield wipers inside the car?
The multi function switch is the lever for your turn signals , windshield wipers , washer etc .
Replace the windshield wipers.
Weak battery or alternator output.
Mary Anderson invented windshield wipers in 1903.
When purchasing windshield wipers that work intermittently, they can be any windshield wipers that are the correct size. The ability to work intermittently is a wiring/fuse ordeal. This does not play a part in the selection of windshield wipers that you choose from.
The windshield wipers go back in forth if you now now what i mean