Wash Operation
WARNING: This page is about a different car, the 2006 Pontiac Montana SV6, 2006 Chevrolet Uplander, and 2006 Buick Terraza. However, it is still accessible from the selected car via links, so may be relevant.
In the WASH position windshield wiper/washer switch supplies a ground signal to the body control module (BCM). The BCM monitors for a low signal condition on this circuit to detect when a WASH cycle is requested. After a short delay, the BCM energizes the wiper relay which will operate the windshield wiper motor at low speed. The wiper motor will continue to operate for 2 wipe cycles after the wash switch is released.