Rear

REAR





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 right 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 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 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.

OPERATING MODES

Following are paragraphs that briefly describe the operation of each of the rear wiper and washer system operating modes.

CONTINUOUS WIPE MODE

When the CONTINUOUS WIPE position of the control sleeve on the control stalk of the multi-function switch is selected the SCM sends an electronic rear wiper switch status message to the FCM, then the FCM energizes the rear wiper relay control coil. This directs battery current through the normally open contacts of the energized rear wiper relay to enable the rear wiper module. The SCM also provides a hard wired output to the rear wiper module indicating the selected mode, and the rear wiper module energizes the rear wiper motor causing the wipers to cycle at a fixed speed.

INTERMITTENT WIPE MODE

When the INTERMITTENT WIPE position of the control sleeve on the control stalk of the multi-function switch is selected the SCM sends an electronic rear wiper switch status message to the FCM, then the FCM energizes the rear wiper relay control coil. This directs battery current through the normally open contacts of the energized rear wiper relay to enable the rear wiper module. The SCM also provides a hard wired output to the rear wiper module indicating the selected mode, and the rear wiper module energizes the rear wiper motor causing the wipers to cycle with a predetermined fixed delay interval between wiper sweeps.

WASH MODE

When the control sleeve of the right multi-function switch is rotated counterclockwise to the rear momentary WASH position for more than about one-half second with the rear wiper system operating, the SCM sends an electronic washer switch status message to the FCM, then the FCM directs battery current and ground to the washer pump/motor unit. This will cause the washer pump/motor unit to be energized in the rear washer direction for as long as the switch is held closed (up to about 10 seconds) and to be de-energized when the control sleeve is released. The SCM also provides a hard wired output to the rear wiper module indicating the selected mode and, if the rear wipers are operating in the intermittent mode, the rear wiper module operates the rear wiper motor at a fixed speed until the control sleeve is released.

WIPE-AFTER-WASH MODE

When the control sleeve of the right multi-function switch is rotated clockwise to the rear momentary WASH position for more than about one-half second while the rear wiper system is not operating, the SCM sends an electronic washer switch status message to the FCM, then the FCM directs battery current and ground to the washer pump/motor unit and energizes the rear wiper relay control coil. This will cause the washer pump/motor unit to be energized in the rear washer direction and the rear wiper module to be enabled for as long as the switch is held closed (up to about 10 seconds) and to be de-energized when the control sleeve is released. The SCM also provides a hard wired output to the rear wiper module indicating the selected mode and the rear wiper module operates the rear wiper motor at a fixed speed until the control sleeve is released plus two additional wipe cycles before the SCM de-energizes the rear wiper relay and parks the rear wiper blade.