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REAR WIPERS/WASHERSAn electrically operated fixed interval intermittent rear wiper and washer system is standard factory-installed equipment on this model. The rear wiper and washer system includes the following major components, which are described in further detail elsewhere in this service information:
- Central Timer Module - The Central Timer Module (CTM) is located on the left cowl side inner panel under the driver side outboard end of the instrument panel. The CTM contains a microprocessor and software that allow it to provide the many electronic functions and features not available with most conventional hard wired wiper and washer systems. The CTM provides the proper rear wiper and washer system features based upon the monitored inputs. The CTM circuitry monitors hard wired switch inputs, as well as message inputs received from other vehicle electronic modules on the Programmable Communications Interface (PCI) data bus network. (Refer to ELECTRICAL/ELECTRONIC CONTROL MODULES/BODY CONTROL/CENTRAL TIMER MODULE - DESCRIPTION).
- Heater-Air Conditioner Control - The vehicle operator controls all rear wiper and washer system functions through two switches that are operated by a single rotary control knob located in the heater-air conditioner control on the instrument panel. The heater-air conditioner control provides a hard wired battery current output to operate the rear washer pump/motor, and sends electronic rear wiper and rear washer switch status messages to the CTM over the PCI data bus network. (Refer to HEATING & AIR CONDITIONING/CONTROLS/A/C HEATER CONTROL - DESCRIPTION).
- Rear Washer Nozzle - The rear washer nozzle is secured by a snap fit onto the top of the liftgate outer panel above the liftgate glass. The rear washer system plumbing is concealed within and routed through the engine compartment and the passenger compartment of the vehicle.
- Rear Washer Pump/Motor - The rear washer pump/motor unit is located in a dedicated hole on the lower outboard side of the washer reservoir, in the right front corner of the engine compartment. The rear washer pump mounting hole is located higher on the reservoir than the front washer pump mounting hole.
- Rear Wiper Arm - The single rear wiper arm is secured by a nut directly to the rear wiper motor output shaft, which extends through the liftgate outer panel near the base of the liftgate glass.
- Rear Wiper Blade - The single rear wiper blade is secured to the rear wiper arm, and is parked near the bottom of the liftgate glass when the rear wiper system is not in operation.
- Rear Wiper Motor - The rear wiper motor output shaft is the only visible component of the rear wiper motor. The remainder of the motor is concealed within the liftgate beneath the liftgate glass opening. The rear wiper motor includes the motor bracket, the rear wiper motor, and the rear wiper motor park switch.
- Rear Wiper Relay - The rear wiper relay is located in the Power Distribution Center (PDC) in the engine compartment near the battery. This relay switches battery current to the rear wiper motor when the CTM grounds the relay control coil.
- Washer Reservoir - The rear washer system shares a single reservoir with the front washer system, but has its own dedicated washer pump/motor and plumbing. The washer reservoir is integral to and located on the right end of the upper radiator shroud. The washer reservoir filler is accessed from the right front corner of the engine compartment.
Features of the rear wiper and washer system include the following:
- Continuous Wipe Mode - When the rear wiper and washer system control knob is rotated to the ON position, the rear wiper will be operated at a fixed speed, continual wipe cycle until the switch sleeve is rotated to the Delay or OFF positions, or until the ignition switch is turned to the OFF position.
- Intermittent Wipe Mode - When the rear wiper and washer system control knob is rotated to one of the four Delay positions, the rear wiper will be operated in a fixed interval, intermittent wipe cycle until the control knob is rotated to the ON or OFF positions, until the control knob is depressed to activate the rear washer system, or until the ignition switch is turned to the OFF position. The intermittent wipe mode delay time has four fixed delay intervals, from a minimum of about five seconds to a maximum of about eight seconds between sweeps.
- Washer Mode - When the rear wiper and washer system control knob is depressed to activate the rear washer system, washer fluid will be dispensed from the washer reservoir onto the liftgate glass through the rear washer nozzle and the rear wiper will operate in a fixed cycle (not intermittent) for as long as the rear washer pump/motor unit remains energized. When the control knob is released from the momentary Wash position, the wipe-after-wash feature will continue to operate the rear wiper at a fixed cycle for about three additional wiper sweeps before returning to the previously selected mode.
Hard wired circuitry connects the rear wiper and washer system components to the electrical system of the vehicle. These hard wired circuits are integral to several wire harnesses, which are routed throughout the vehicle and retained by many different methods. These circuits may be connected to each other, to the vehicle electrical system and to the rear wiper and washer system components through the use of a combination of soldered splices, splice block connectors, and many different types of wire harness terminal connectors and insulators. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, further details on wire harness routing and retention, as well as pin-out and location views for the various wire harness connectors, splices and grounds.
The rear wiper and washer system is intended 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 outside liftgate glass surface that might be encountered while driving under numerous inclement operating conditions. The vehicle operator initiates all rear wiper and washer system functions with the rear wiper and washer switch located in the heater-air conditioner control, just below the radio on the instrument panel. Rotating the control knob to a detent position selects the rear wiper system operating mode. Depressing the control knob activates the rear washer system.
When the ignition switch is in the ON position, battery current from a fuse in the Junction Block (JB) is provided to the rear wiper and washer system switches in the heater-air conditioner control through a fused ignition switch output (run) circuit. When a rear wiper switch mode is selected, the circuitry within the heater-air conditioner control sends an electronic wiper switch status message over the Programmable Communications Interface (PCI) data bus to the Central Timer Module (CTM). The CTM then uses its internal wiper system programming, electronic switch status messages, and a hard wired input from the rear wiper motor park switch on the rear wiper park switch sense circuit to determine the proper hard wired control output to provide to the rear wiper relay on the rear wiper relay control circuit. When the CTM energizes the rear wiper relay control coil, the relay directs battery current to the rear wiper motor brushes on the rear wiper motor control circuit, which causes the rear wiper motor to operate until the CTM de-energizes the rear wiper relay. When the rear wiper and washer switch Wash mode is selected, the Wash position circuitry within the switch directs battery current to the rear washer pump/motor through a hard wired rear washer pump/motor control signal circuit and sends an electronic Wash switch status message to the CTM over the PCI data bus. The CTM then uses its internal washer system programming to operate the rear wiper motor for as long as the washer switch is depressed plus about three additional fixed wipe cycles.
The intermittent wipe and wipe-after-wash features of the rear wiper and washer system are both provided by the CTM. In order to provide these features, the CTM monitors the wiper and washer switch state messages from the heater-air conditioner control and the rear wiper motor park switch state. The CTM monitors the rear wiper motor operation through ground pulse inputs received from the rear wiper motor park switch through the rear wiper park switch sense circuit. This arrangement allows the CTM to count the number of wiper sweeps after the washer switch state message changes to open during fixed cycle wiper operation, and to calculate the proper timing to begin the next wiper blade sweep during fixed intermittent cycle wiper operation.
When the OFF position of the rear wiper and washer switch is selected, one of three events is possible. The event that will occur depends upon the position of the wiper blade on the liftgate glass and the mode the wiper motor is operating under at the moment that the OFF position is selected. If the wiper blade is in the down position on the glass and is operating in the fixed or fixed intermittent cycle modes when the OFF position is selected, the park switch is open and the CTM de-energizes the rear wiper relay control coil causing the rear wiper motor to cease to operation. If the wiper blade is not in the down position on the glass and is operating in the fixed or fixed intermittent cycle modes when the OFF position is selected, the park switch is closed to ground and the CTM keeps the rear wiper relay control coil energized to operate the rear wiper motor until the rear wiper blade is in the down position on the glass and the park switch input is open circuit. The third event occurs with the rear wiper operating in the wipe-after-wash mode when the OFF position is selected, in which case the CTM will continue to run the wiper motor until the completion of about three wiper blade sweeps before the rear wiper blade is parked. The CTM will also run the rear wiper motor to park the rear wiper blade if the ignition switch is turned to the OFF position while the rear wiper system is still operating.
The rear wiper and washer systems will operate only when the ignition switch is in the ON position. A fuse in the Junction Block (JB) protects the circuitry of the rear washer pump/motor, while a separate fuse in the Power Distribution Center (PDC) protects the circuitry for the rear wiper motor. The CTM microprocessor continuously monitors all of the rear wiper system electrical circuits to determine the system readiness. If the CTM detects a monitored system fault, it sets an active Diagnostic Trouble Code (DTC) and will suspend rear wiper system operation. For complete diagnosis of the rear wiper system, a DRB III scan tool is required. Refer to the appropriate diagnostic information. Refer to the owner's manual in the vehicle glove box for more information on the features, use and operation of the rear wiper and washer system.
Fig.3 Rear Check Valve:
REAR CHECK VALVE
Models equipped with the rear wiper and washer system have a check valve installed in the rear washer system plumbing. The rear check valve is located in the engine compartment near the back of the right front wheel house, where it is installed in the rear washer supply hose between the engine compartment and passenger compartment body sections of the rear washer hose. The rear check valve consists of a molded plastic valve body with a raised center section that is tapered in the direction of the flow through the valve. A barbed hose nipple is formed on each side of the raised center section of the valve body Within the rear check valve body a small check ball is held against an integral valve seat at one end of the valve by a small coiled spring. The rear check valve cannot be adjusted or repaired and, if faulty or damaged, it must be replaced.
The rear check valve provides more than one function in this application. It serves as an in-line connector fitting between the engine compartment and body sections of the rear washer supply hose. It also prevents washer fluid from draining out of the rear washer supply hoses back to the washer reservoir. This drain-back would result in a lengthy delay from when the rear washer switch is actuated until washer fluid was dispensed through the rear washer nozzle, because the rear washer pump would have to refill the rear washer plumbing from the reservoir to the nozzle. Finally the rear check valve prevents washer fluid from siphoning through the rear washer nozzle after the rear washer system is turned OFF. When the rear washer pump pressurizes and pumps washer fluid from the reservoir through the rear washer plumbing, the fluid pressure overrides the spring pressure applied to the check ball within the valve and unseats the check ball, allowing washer fluid to flow toward the rear washer nozzle. When the rear washer pump stops operating, spring pressure seats the check ball in the valve and fluid flow in either direction within the rear washer plumbing is prevented.