Circuit/System Description
WARNING: This page is about a different car, the 2007 Saturn Sky. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) monitors the voltage level on the windshield wiper motor relay coil supply voltage circuit that controls the WPR 70 On/Off relay. The voltage level on this circuit should be low while the wiper system is off and the relay is de-energized. The voltage will be near system voltage when the relay is energized. After the BCM receives a low, delay, or mist signal from the wiper/washer switch, it responds by applying battery voltage to the wiper motor relay coil supply voltage circuit energizing the WPR 70 On/Off relay.