Heated Windshield Washers

WARNING: This page is about a different car, the 2009 GMC Sierra, 2009 GMC Cab & Chassis Sierra, 2009 Chevrolet Silverado, and 2009 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The windshield washer solvent heater operates with the standard windshield wiper washer system, and when a heated washer cycle is activated the solvent heater controls the windshield washers through the washer switch signal circuit to the body control module (BCM). The heater is supplied with high current power and ground circuits that are used to energize the heater coils. The low current logic voltage is supplied to the heater through the RUN relay in the underhood fuse block. The RUN relay is a PCB relay energized by the BCM only while the engine is running. The heated washer cycle operation is activated by a separate switch located on the instrument panel accessory switch assembly. When the heated washer fluid switch is pressed the heated washer switch signal circuit is momentarily grounded and the heated washer cycle is activated. During the heated wash cycle the 3 heater elements in the solvent heater are energized, and when the solvent temperature reaches approximately 70° C (160° F) the heater grounds the washer switch signal circuit until the heated solvent is dispensed. The heated washer cycle will run 4 heat and wash actions unless deacitvated by the heated washer switch signal.