Front Wipers/Washers - Service Information: Operation: Notes
The front wiper and washer system is designed to provide the vehicle operator with a convenient, safe, and reliable means of maintaining visibility through the windshield glass. The various components of this system are designed to convert electrical energy produced by the vehicle electrical system into the mechanical action of the wiper blades to wipe the outside surface of the glass, as well as into the hydraulic action of the washer system to apply washer fluid stored in an on-board reservoir to the area of the glass to be wiped. When combined, these components provide the means to effectively maintain clear visibility for the vehicle operator by removing excess accumulations of rain, snow, bugs, mud, or other minor debris from the outside windshield glass surface that might be encountered while driving the vehicle under numerous types of inclement operating conditions.
The vehicle operator initiates all front and rear wiper and washer system functions with the control stalk of the right (wiper) multi-function switch (1) that extends from the right side of the steering column. Rotating the front wiper control knob (2) on the end of the control stalk, selects the Off, Delay, Low, or High operating modes of the front wiper system. In the Delay mode, the control knob also allows the vehicle operator to select from one of five intermittent wipe Delay intervals. Pulling the control stalk rearward actuates the momentary front washer system switch, which selects the Wash and Wipe-After-Wash modes depending upon when and how long the front Wash switch is held closed. Rotating the rear wiper control knob (3) on control stalk, selects all operating modes of the rear wiper system. The multi-function switch provides hard wired resistor multiplexed inputs to the steering control module (SCM) for all of the wiper and washer system functions. The SCM then sends electronic messages to the front control module (FCM) over the controller area network (CAN) data bus requesting the appropriate wiper and washer system operating modes.
Front wiper/washer system operation is completely controlled by the SCM and FCM logic circuits, and that logic will only allow these systems to operate when the ignition switch is in the Accessory or On positions. Battery current is directed from the integrated power module (IPM) to the wiper on/off relay and the wiper high/low relay in the IPM through a fused B(+) circuit. The FCM uses low side drivers to control wiper system operation by energizing or de-energizing the wiper high/low and wiper on/off relays. The FCM uses a high side driver to control the operation of the windshield washer pump. The right multi-function switch circuitry receives a clean ground output from the SCM on a multi-function switch return circuit, then provides resistor multiplexed inputs to the SCM on an intermittent wipe mux circuit to indicate the selected wiper system mode and on a wash/beam select mux circuit to indicate the selected washer system mode.
The hard wired circuits and components of the wiper and washer system may be diagnosed and tested using conventional diagnostic tools and procedures. However, conventional diagnostic methods may not prove conclusive in the diagnosis of the SCM, FCM or the electronic message inputs to or outputs from the SCM or the FCM that control the wiper and washer system operating modes. The most reliable, efficient, and accurate means to diagnose the SCM or the FCM inputs and outputs related to the various wiper and washer system operating modes requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.