Rear Wiper And Washer System: 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 rear door 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 rear door glass surface that might be encountered while driving the vehicle under numerous types of inclement operating conditions.
Two rear wiper systems are available: The standard intermittent wipe system, or an optional automatic wipe system. The vehicle operator initiates all rear wiper and washer system functions with the controls on the end of the multi-function switch control stalk 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 detent positions marked on the fixed band of the stalk selects the 0 (Off) or I (Intermittent) rear wiper system operating modes, while rotating the sleeve to the momentary upward position from 0 or momentary downward position from I selects rear washer system operation.
Rear wiper and washer system operation is completely controlled by the Body Control Module (BCM) (also known as the Signal Acquisition and Actuation Module/SAM) logic circuits based upon electronic wipe command and wash command message inputs received from the Steering Control Module (SCM) (also known as the steering column module/MRM) based upon the selected multi-function switch position and, on vehicles so equipped, from the Roof Control Module (RCM) (also known as the Overhead Control Panel/OCP control unit or DBE) based upon inputs received from the rain/light sensor. The BCM will only allow these systems to operate when the ignition switch is in the ON position. The BCM also uses inputs from the backup lamp switch and the two rear door ajar switches for rear wiper system control. The BCM uses high side drivers to control wiper system operation by energizing or de-energizing the rear wiper relays integral to the rear wiper motors, and a low side driver to control the rear washer pump/motor unit.
The hard wired circuits and components of the rear wiper and washer system may be diagnosed using conventional diagnostic tools and procedures. Refer to SYSTEM WIRING DIAGRAMS . However, conventional diagnostic methods will not prove conclusive in the diagnosis of the rear wiper and washer system or the electronic controls or 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.