Same thing happening here, but wierder!
Got a '89 Landy 90 with four positions and it's:
Two up (Should be on fast) - Wipers stay off
One up (Should be on norm) - Wipers stay off
Parked (Should be off) - Windscreen washer starts up (?!)
Down (Intermittent) - Wipers on norm.
Bought new...