Circuit/System Description
WARNING: This page is about a different car, the 2008 Cadillac CTS. However, it is still accessible from the selected car via links, so may be relevant.
The headlamp washer function is controlled by the body control module (BCM). When the headlamp 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 Headlamp WSH Relay energizing the relay. With the relay energized, battery voltage is applied through the switch contacts of the relay, the Headlamp WSW/PUMP Fuse and the control circuit to the Headlamp washer fluid pump.