Rear Wipers & Washers
An electrically operated 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:
- Front Control Module - The Front Control Module (FCM) is integral to the Integrated Power Module (IPM). The FCM/IPM is located in the engine compartment, near the battery and the Power Distribution Center (PDC).
- Heater-Air Conditioner Control (1) - The vehicle operator controls all rear wiper and washer system functions through two switches that are operated by a single rotary control knob in the heater-air conditioner control located in the center stack area of the instrument panel. The heater-air conditioner control sends electronic rear wiper and rear washer switch status messages to the ElectroMechanical Instrument Cluster (EMIC over the Controller Area Network (CAN) data bus.
- Instrument Cluster - The ElectroMechanical Instrument Cluster (EMIC) is also known as the Cab Control NO:de (CCN) in this vehicle. The EMIC/CCN is located in the instrument panel above the steering column opening, directly in front of the driver.
- Rear Washer Nozzle (2) - A fluidic rear washer nozzle is secured by latch features to a mounting hole in the liftgate header panel and to the right of the Center High-Mounted Stop Lamp (CHMSL) above the liftgate glass.
- Rear Washer Plumbing - The plumbing for the washer system consists of rubber hoses and molded plastic fittings. The plumbing is routed along the underside of the Power Distribution Center (PDC) bracket to the engine compartment from the washer reservoir. The rear washer hose is routed through the dash panel from the engine compartment into the passenger compartment, up the left A-pillar where it is connected to a hose integral to the headliner that runs from the A-pillar to the rear washer nozzle on the upper liftgate header.
- 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 center of 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 with an integral latch, and is parked near the bottom of the liftgate glass when the rear wiper system is not in operation.
Rear Wiper Motor (3) - 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.
Washer Reservoir - The rear washer system shares a single reservoir and reversible pump with the front washer system, but has its own dedicated plumbing. The washer reservoir is integral to the engine coolant reserve bottle located in the left front corner of the engine compartment.
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 designed to provide the vehicle operator with a convenient, safe, and reliable means of maintaining visibility through the lift-gate 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 onboard 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 a corner of the heater-air conditioner control (2), just below the radio on the instrument panel. Rotating the rear wiper and washer switch control knob (1) to a detent position selects the rear wiper system operating mode, either continuous or intermittent. Intermittent operation provides one of four fixed delay intervals, from five to 21 seconds. Depressing the control knob activates the rear washer system. When a rear wiper or washer switch mode is selected, the circuitry within the heater-air conditioner control sends an electronic rear wiper/washer switch status message over the Controller Area Network (CAN) data bus to the ElectroMechanical Instrument Cluster (EMIC). The instrument cluster then sends electronic messages to the Front Control Module (FCM) over the CAN data bus requesting the appropriate rear wiper and washer system operating modes.
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 instrument cluster, the FCM, or the electronic message inputs to or outputs from the instrument cluster or FCM that control the rear wiper and washer system operating modes. The most reliable, efficient, and accurate means to diagnose the instrument cluster or the FCM inputs and outputs related to the various wiper and washer system operating modes 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 On position of the rear wiper/washer control knob is selected the instrument cluster sends an electronic wiper switch message to the FCM, then the FCM energizes the rear wiper relay. This directs battery current to the rear wiper motor, causing the wiper to cycle continuously at a fixed speed until the FCM de-energizes the rear wiper relay.
INTERMITTENT WIPE MODE
When the rear wiper/washer control knob is moved to one of the Delay interval positions the instrument cluster sends an electronic wiper switch delay message to the FCM, then the FCM electronic intermittent wipe logic circuit responds by calculating the correct length of time between wiper sweeps based upon the selected delay interval input. The FCM monitors the changing state of the rear wiper motor park switch through a hard wired park switch sense input. This input allows the FCM to determine the proper intervals at which to energize and de-energize the rear wiper relay to operate the wiper motor intermittently for one cycle at a time.
WASH MODE
When the rear wiper/washer control knob is depressed to the momentary Wash position, the instrument cluster sends an electronic washer switch 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 for as long as the Wash switch is held closed up to about thirty seconds, and to de-energize when the rear wiper/washer control knob is released.
WASH MODE
When the rear wiper/washer control knob is depressed to the momentary Wash position, the instrument cluster sends an electronic washer switch 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 for as long as the Wash switch is held closed up to about thirty seconds, and to de-energize when the rear wiper/washer control knob is released.
WIPE-AFTER-WASH MODE
When the rear wiper/washer control knob is released from the momentary Wash position, the instrument cluster sends an electronic washer switch message to the FCM. The FCM de-energizes the washer pump/motor, but allows the rear wiper motor to operate for several wipe cycles before it de-energizes the rear wiper relay.
OFF MODE
When the Off position of the rear wiper/washer control knob 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 the rear wiper system is operating in the fixed or fixed intermittent cycle modes when the Off position is selected, the park switch is open and the FCM 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 FCM 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 an 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 FCM will continue to run the wiper motor until the completion of about three wiper blade sweeps before the rear wiper blade is parked. The FCM 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.