Principles of Operation (How Does it Work?)

Wipers and Washers
The wiper and washer systems are controlled by the Front Electronic Module (FEM). The wiper/washer portion of the multifunction switch is hardwired to the FEM. When the switch is moved to the desired position, the FEM processes this information and outputs the appropriate command(s) to one of three relays. The relays control the wiper high and low motor speeds and washer pump actuation. Intermittent wiper speed control can vary dependent upon vehicle speed. This is accomplished by the FEM receiving vehicle speed information from the anti-lock brake control module and throttle position status from the Powertrain Control Module (PCM). When the wiper switch is in any of the intermittent positions, the FEM will process the information from the PCM and anti-lock brake control module and decrease the wiper delay time as vehicle speed increases.

Low Washer Fluid Level Lamp/Indicator
The low washer fluid lamp/indicator feature is controlled by the FEM and instrument cluster. The low washer fluid switch is hardwired to the FEM. If fluid is low, the FEM will send a message via the Standard Corporate Protocol (SCP) communication network to the instrument cluster. The instrument cluster will then process the message and output an audible and visual warning.