Circuit/System Description
WARNING: This page is about a different car, the 2008 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
When the windshield wiper switch is in the ON position, it sends a voltage signal through a 24K ohm resistor and the windshield wiper switch signal 2 circuit to the windshield wiper/washer module indicating the wiper request. This voltage signal is also sent to the instrument panel module (IPM) indicating the wiper request. When the windshield washer switch is pressed, battery positive voltage is applied through the switch contacts by-passing the 24K ohm resistor, then through the same windshield wiper switch signal 2 circuit to the wiper/washer module and the IPM indicating the washer request. The IPM counts each washer request and on the fourth request it will activate the low side drive output that controls the headlamp washer relay.