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 outer surface of the liftgate flip-up 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 stalk of the right (wiper) multi-function switch that extends from the right side of the steering column, just below the steering wheel. Rotating the control knob on the control stalk to a detent position selects the OFF or DELAY (or INTERMITTENT) rear wiper system operating modes. Pushing the control stalk to a momentary forward position actuates the rear washer system switch, which selects the rear wash mode and dispenses washer fluid in the wipe pattern on the liftgate glass for as long as the switch is held closed.

The right multi-function switch provides hard wired analog and resistor multiplexed inputs to the Body Control Module (BCM) for all of the wiper and washer system functions. The BCM then provides the appropriate hard wired control outputs to energize or de-energize the wiper and washer relays soldered onto its printed circuit board. The relays control the flow of battery current to the rear wiper motor and the washer pump motor, invoking the requested wiper and washer system operating modes. Rear wiper and washer system operation is completely controlled by the BCM logic circuits, and that logic will only allow these systems to operate when the ignition switch is in the ACCESSORY or ON positions.

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.

INTERMITTENT WIPE MODE

When the right (wiper) multi-function switch control knob is moved to the DELAY (or INTERMITTENT) position, the switch provides a resistor multiplexed input to the BCM. The BCM responds by energizing a relay that directs battery current to the rear wiper motor, causing the rear wiper to cycle at a fixed intermittent speed.

When the OFF position of the right multi-function switch control knob is selected, the switch provides a resistor multiplexed input to the BCM. The event that occurs depends upon the position of the wiper blade on the liftgate glass at the moment that the control knob OFF position is selected.

If the wiper blade is in the down position on the liftgate glass when the OFF position is selected, the park switch that is integral to the wiper motor is closed to ground, which provides a hard wired park switch sense input to the BCM. The BCM then de-energizes the wiper motor and the wiper motor ceases to operate. If the wiper blades are not in the down position on the liftgate glass at the moment the OFF position is selected, the park switch is an open circuit and the BCM continues running the wiper motor at low speed until the wiper blade is in the down position on the liftgate glass and the park switch input to the BCM is again closed to ground.

WASH MODE

When the control stalk of the right (wiper) multi-function switch is pushed forward to the momentary rear WASH position, the switch provides a resistor multiplexed input to the BCM. The BCM responds by directing battery current and ground to the washer pump/motor as well as battery current to the rear wiper motor. The washer pump is de-energized as soon as the control stalk is released, but the rear wiper motor continues to operate for several continuous cycles before parking at the base of the glass or reverting to the fixed delay interval operation. The BCM uses a hard wired output from a park switch internal to the rear wiper motor as an additional logic input to monitor the position of the rear wiper blade on the glass and to control the number of wiper sweeps following washer operation.