Wipers/Washers - 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 flip-up 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 outside liftgate flip-up glass surface that might be encountered while driving the vehicle under numerous types of inclement operating conditions.
The vehicle operator initiates all rear wiper and washer system functions with the control sleeve (3) on the control stalk (1) of the right multi-function switch that extends from the right side of the steering column, just below the steering wheel. Rotating the control sleeve on the control stalk to the various detent and momentary positions selects the rear wiper and washer system operating modes. The multi-function switch provides resistor multiplexed inputs to the Steering Control Module (SCM) for all of the rear wiper and washer system functions.
The SCM sends an electronic rear wiper/washer switch status message over the Controller Area Network (CAN) data bus to the Front Control Module (FCM) indicating the selected rear wiper and washer system operating mode. The FCM provides battery voltage and ground to operate the washer pump/motor unit and a control output to the rear wiper relay, which provides battery voltage to operate the rear wiper module. The SCM also provides hard wired control outputs to the rear wiper module on two circuits that indicate the selected operating mode and delay interval that the rear wiper module uses to control rear wiper motor operation.
Rear 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 rear wiper relay in the Junction Block (JB) through a fused B(+) circuit. 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 to indicate the selected rear wiper and washer system operating mode.
The hard wired circuits and components of the rear 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, the FCM or the electronic message inputs to or outputs from the SCM or the FCM that control the rear 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 rear wiper and washer system operating modes requires the use of a diagnostic scan tool. Refer to the appropriate diagnostic information.