GM Service Manual Online
For 1990-2009 cars only

Park Operation

While the wiper is operating, the park switch in the wiper motor assembly is closed. When the wiper switch is set to OFF, voltage is applied through the park switch contacts to keep the wiper motor running until the wiper reaches park position. When in the park position, the park switch opens and the wiper motor stops.

Washer Operation

When the washer switch is held in the WASH position, the wiper/washer switch assembly applies battery voltage to terminal B of the wiper motor assembly causing it to begin wiper operation. The wiper/washer switch assembly also applies battery voltage to terminal A of the washer pump, through CKT 392, causing the washer pump to start spraying until the wiper/washer switch is released from the WASH position.