Wiper System & Washer System (Service Information): Operation: Rear: Notes
The rear wiper and washer system is designed to provide the vehicle operator with a convenient, safe and reliable means of maintaining visibility through the liftgate 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 blade 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 outer surface of the liftgate glass 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 knob (1) and control sleeve (2) on the control stalk (3) of the multifunction switch that extends from the left side of the steering column, just below the steering wheel. Rotating the control sleeve on the control stalk to the ON, OFF or Intermittent (INT ) detent positions or a momentary Wash position selects the rear wiper and washer system operating modes.
The multifunction switch provides hardwired analog and digital inputs to the microcontroller internal to the Steering Column Control Module (SCCM) for all of the wiper and washer system functions. The SCCM microcontroller then sends electronic wiper switch and washer switch request messages to the Body Control Module (BCM) over the Controller Area Network (CAN) data bus requesting the appropriate wiper and washer system operating modes.
Rear wiper and washer system operation is completely controlled by the SCCM and BCM logic circuits, and that logic will only allow these systems to operate when the status of he ignition switch is Accessory or ON. The BCM uses a High Side Driver (HSD) to control the rear wiper relay integral to the Printed Circuit Board (PCB) within the Power Distribution Center (PDC) that controls rear wiper system operation by energizing or de-energizing the rear wiper motor. The multifunction switch circuitry receives battery current and a clean ground output from the SCCM microcontroller, then provides analog and digital inputs to the microcontroller to indicate the selected rear wiper and rear washer system mode.
The hardwired circuits and components of the rear wiper and washer system may be diagnosed using conventional diagnostic tools and procedures. Refer to the appropriate wiring information. However, conventional diagnostic methods will not prove conclusive in the diagnosis of the electronic controls and communication between other modules and devices that provide some features of the rear wiper and washer system. The most reliable, efficient and accurate means to diagnose the rear wiper and washer system or the electronic controls and communication related to rear wiper and washer system operation requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.