After some more thought... I had the realization that WASH probably un-grounds the park switch, grounds the low speed terminal, and after a short delay of 2 or 3 seconds, un-grounds the low term, re-enables the park switch ground. This will cause two or three wipes and would explain why modern systems need an insulated park switch ground, wiper motor. I will also postulate that the OE Monza system had no multi wipe wash function.
Edit: Incorrect