Circuit/System Description
WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.
The windshield washer function is controlled by the body control module (BCM). When the washer switch is pressed, ground is applied through the switch contacts and the signal circuit to the BCM indicating the wash request. The BCM then applies ground through the control circuit to the coil side of the WS WASH relay energizing the relay. With the relay energized, battery voltage is applied through the switch contacts of the relay, the WSW fuse, and the control circuit to the windshield washer fluid pump.