Hi Operation
WARNING: This page is about a different car, the 2002 Buick Regal and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
When the wiper/washer switch is in the HIGH position the accessory voltage to the wiper/washer switch is closed to the wiper motor high speed circuit. The accessory voltage on the high speed circuit is supplied to the wiper motor module and is used to operate the wiper motor at high speed. During HIGH speed wiper motor operation the wiper switch signal 1 and signal 2 circuits are at the LOW speed signal voltages, but the LOW speed signal circuit inputs to the wiper motor module have no effect on wiper motor high speed operation.