Wiper and Washer Systems: Description and Operation
WIPERS/WASHERSDESCRIPTION
FRONT
An electrically operated intermittent front wiper and washer system is standard factory-installed safety equipment on this model. The wiper and washer system includes the following major components, which are described in further detail:
- 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).
- Front Washer Nozzle (2) - Two fluidic washer nozzles with integral check valves are secured by latch features to dedicated openings in the hood panel near the base of the windshield.
- Front 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 front washer hose is routed across the underside of the hood panel to the washer nozzles.
- Front Wiper Arm - The two wiper arms are secured with nuts to the threaded ends of the two wiper pivot shafts, which extend through the cowl plenum cover/grille panel located near the base of the windshield. The right arm is articulated by a unique linkage arrangement to increase the wiped area of the windshield glass.
- Front Wiper Blade - The two unequal length wiper blades are secured to the two wiper arms with an integral latch, and are parked on the glass near the bottom of the windshield when the wiper system is not in operation.
- Front Wiper Module (3) - The wiper pivot shafts are the only visible components of the front wiper module. The remainder of the module is concealed within the engine compartment beneath the cowl plenum cover/grille panel. The wiper module includes a cast aluminum wiper module bracket, four rubber-isolated wiper module mounts, the wiper motor, the wiper motor crank arm, the two wiper drive links, the two powered wiper pivots, and a static pivot point that is located outboard of the right pivot for the articulating link of the right wiper arm.
- Instrument Cluster - The ElectroMechanical Instrument Cluster (EMIC) is also known as the Cab Control Node (CCN) in this vehicle. The EMIC/CCN is located in the instrument panel above the steering column opening, directly in front of the driver.
- Multi-Function Switch (4) - The multi-function switch is located on the top of the steering column, just below the steering wheel. A control stalk that extends from the left side of the switch has a control knob on the end that is dedicated to providing all of the driver controls for the front wiper and washer systems.
- Washer Fluid Level Switch - The washer fluid level switch is located in a dedicated hole on the lower, rearward facing surface of the washer reservoir, ahead of the left front wheel house splash shield.
- Washer Pump/Motor - The reversible electric washer pump/motor unit is located in a dedicated hole on the lower, rearward facing surface of the washer reservoir, ahead of the left front wheel house splash shield. This single reversible washer pump/motor provides washer fluid to either the front or rear washer system plumbing, depending upon the direction of the pump motor rotation.
- Washer Reservoir (1) - The washer reservoir is combined with the engine coolant reserve bottle located on the radiator support to the left of the air conditioning condenser in the engine compartment. This combined reservoir has separate, clearly identified washer fluid and engine coolant filler caps that are accessed from the left front corner of the engine compartment.
- Wiper High/Low Relay - The wiper high/low relay is an International Standards Organization (ISO) micro relay located in the Power Distribution Center (PDC) in the engine compartment near the battery.
- Wiper On/Off Relay - The wiper on/off relay is an International Standards Organization (ISO) micro relay located in the Power Distribution Center (PDC) in the engine compartment near the battery.
Hard wired circuitry connects the front 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 front 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.
REAR
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:
- 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 Node (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.
OPERATION
FRONT
The front wiper and washer system is designed to provide the vehicle operator with a convenient, safe, and reliable means of maintaining visibility through the windshield 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 blades 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 windshield glass surface that might be encountered while driving the vehicle under numerous types of inclement operating conditions.
The vehicle operator initiates all front wiper and washer system functions with the control knob (1) on the end of the control stalk (2) of the multi-function switch that extends from the left side of the steering column, just below the steering wheel. Rotating the control knob on the end of the control stalk, selects the Off, Delay, Low, or High wiper system operating modes. In the Delay mode, the control knob also allows the vehicle operator to select from one of five intermittent wipe Delay intervals. Depressing the control knob towards the steering column actuates the momentary washer system switch, which selects the Wash, and Wipe-After-Wash Modes depending upon when and how long the switch is held closed. The multi-function switch provides hard wired resistor multiplexed inputs to the instrument cluster for all of the wiper and washer system functions. The instrument cluster then sends electronic messages to the Front Control Module (FCM) over the Controller Area Network (CAN) data bus requesting the appropriate front wiper and washer system operating modes.
Front wiper and washer system operation are completely controlled by the instrument cluster 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 a B(+) fuse in the Integrated Power Module (IPM) to the wiper on/off relay and the wiper high/low relay in the PDC through a fused B(+) circuit. The FCM uses low side drivers to control wiper system operation by energizing or de-energizing the wiper high/low and wiper on/off relays. The FCM uses both high side and low side drivers to control the operation of the washer pump/motor unit. The multi-function switch circuitry receives a clean ground output from the instrument cluster on a multi-function switch return circuit, then provides resistor multiplexed inputs to the instrument cluster on an intermittent wipe mux circuit to indicate the selected wiper system mode and on a wash/beam select mux circuit to indicate the selected washer system mode.
The hard wired circuits and components of the front 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 front 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.
OPERATING MODES
Following are paragraphs that briefly describe the operation of each of the wiper and washer system operating modes.
CONTINUOUS WIPE MODE
When the Low position of the control knob on the control stalk of the multi-function switch is selected the instrument cluster sends an electronic wiper switch low message to the FCM, then the FCM energizes the wiper on/off relay. This directs battery current through the normally open contacts of the energized wiper on/off relay and the normally closed contacts of the de-energized wiper high/low relay to the low speed brush of the wiper motor, causing the wipers to cycle at low speed.
When the High position of the control knob is selected the instrument cluster sends an electronic wiper switch high message to the FCM, then the FCM energizes both the wiper on/off relay and the wiper high/low relay. This directs battery current through the normally open contacts of the energized wiper on/off relay and the normally open contacts of the energized wiper high/low relay to the high speed brush of the wiper motor, causing the wipers to cycle at high speed.
When the Off position of the multi-function switch control knob is selected, the instrument cluster sends an electronic wiper switch off message to the FCM. If the wiper motor was operating at high speed, the FCM immediately de-energizes the wiper high/low relay causing the wiper motor to return to low speed operation. Then one of two events will occur. The event that occurs depends upon the position of the wiper blades on the windshield at the moment that the control knob Off position is selected.
If the wiper blades are in the down position on the windshield when the Off position is selected, the park switch that is integral to the wiper motor is closed to ground and provides a hard wired park switch sense input to the FCM. The FCM then de-energizes the wiper on/off relay and the wiper motor ceases to operate. If the wiper blades are not in the down position on the windshield at the moment the Off position is selected, the park switch is an open circuit and the FCM keeps the wiper on/off relay energized, which causes the wiper motor to continue running at low speed until the wiper blades are in the down position on the windshield and the park switch input to the FCM is again closed to ground.
INTERMITTENT WIPE MODE
When the control knob on the control stalk of the multi-function switch 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 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 wiper on/off relay to operate the wiper motor intermittently for one low speed cycle at a time. The FCM logic is also programmed to provide vehicle speed sensitivity to the selected intermittent wipe delay intervals. In order to provide this feature the FCM monitors electronic vehicle speed messages from the Powertrain Control Module (PCM) and doubles the selected delay interval whenever the vehicle speed is about sixteen kilometers-per-hour (ten miles-per-hour) or less.
WASH MODE
When the control knob on the control stalk of the multi-function switch is depressed to the momentary Wash position for more than about one-half second, 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 ten seconds, and to de-energize when the front Wash switch is released.
When the control knob is depressed to the momentary Wash position while the wiper system is operating in one of the Delay interval positions, the washer pump/motor operation is the same. However, the FCM also energizes the wiper on/off relay to override the selected delay interval and operate the wiper motor in a continuous low speed mode for as long as the control knob is held depressed, then de-energizes the relay and reverts to the selected delay mode interval several wipe cycles after the control knob is released. If the control knob is held depressed for more than about ten seconds, the FCM will suspend washer pump/motor operation until the knob is released for about two seconds, then cycled back to the Wash position.
WIPE-AFTER-WASH MODE
When the control knob on the control stalk of the multi-function switch is depressed to the momentary Wash position for more than about one-half second while the wiper system is not operating, 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 and energizes the wiper on/off relay. This will cause the washer pump/motor unit to be energized and operate the wiper motor in a continuous low speed mode for as long as the Wash switch is held closed up to about ten seconds. When the control knob is released, the FCM de-energizes the washer pump/motor unit, but allows the wiper motor to operate for several additional wipe cycles before it de-energizes the wiper on/off relay and parks the wiper blades near the base of the windshield.
If the control knob is held depressed for more than about ten seconds, the FCM will suspend washer pump/motor operation until the knob is released for about two seconds, then cycled back to the Wash position; however, the wipers will continue to operate for as long as the Wash switch is held closed. The FCM monitors the changing state of the wiper motor park switch through a hard wired wiper park switch sense circuit input. This input allows the FCM to count the number of wipe cycles that occur after the Wash switch is released, and to determine the proper interval at which to de-energize the wiper on/off relay to complete the wipe-after-wash mode cycle.
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 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 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 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 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 heater-air conditioner control, the FCM, or the electronic message inputs to or outputs from the heater-air conditioner control or FCM that control the rear wiper and washer system operating modes. The most reliable, efficient, and accurate means to diagnose the heater-air conditioner control 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.
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.
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.