Wiper and Washer Systems: Description and Operation
WIPERS/WASHERSDESCRIPTION
An electrically operated intermittent 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:
- Check Valve - The washer system check valve is integral to the wye fitting located in the washer plumbing between the cowl plenum washer hose and the washer nozzles, and is concealed beneath the cowl plenum cover/grille panel at the base of the windshield.
- Front Control Module - The Front Control Module (FCM) is integral to the Integrated Power Module (IPM)/ Power Distribution Center (PDC). The FCM/IPM/PDC is located in the engine compartment, near the battery.
- Instrument Cluster - The ElectroMechanical Instrument Cluster (EMIC) is also referred to 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, outboard surface of the washer reservoir, ahead of the right front wheel house splash shield.
- Washer Nozzle (3) - Two fluidic washer nozzles are secured with integral latch features to dedicated openings in the cowl plenum cover/grille panel located near the base of the windshield.
- Washer Plumbing - The plumbing for the washer system consists of rubber hoses and molded plastic fittings. The plumbing is routed along the right side of the engine compartment from the washer reservoir, and through a rubber grommet and hole near the right end of the cowl plenum panel to the washer nozzle fittings on the underside of the cowl plenum cover/grille panel.
- Washer Pump/Motor - The electric washer pump/motor unit is located in a dedicated hole on the outboard surface of the washer reservoir, ahead of the right front wheel house splash shield.
- Washer Reservoir (1) - The washer reservoir is combined with the engine coolant reserve bottle located on the radiator support to the right of the engine cooling/air conditioning condenser module in the engine compartment. This combined reservoir has separate, clearly identified washer fluid and engine coolant filler caps that are accessed from the right front corner of the engine compartment.
- Wiper Arm & Blade - 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 two 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.
- Wiper High/Low Relay - The wiper high/low relay is an International Standards Organization (ISO) micro relay located in the Integrated Power Module (IPM)/Power Distribution Center (PDC) in the engine compartment near the battery.
- Wiper Module (2) - The wiper pivot shafts are the only visible components of the wiper module. The remainder of the module is concealed within the cowl plenum area beneath the cowl plenum cover/grille panel. The wiper module includes the wiper module bracket, four rubber-isolated wiper module mounts, the wiper motor, the wiper motor crank arm, the two wiper drive links, and the two wiper pivots.
- Wiper On/Off Relay - The wiper on/off relay is an International Standards Organization (ISO) micro relay located in the Integrated Power Module (IPM)/Power Distribution Center (PDC) in the engine compartment near the battery.
Hard wired circuitry connects the 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 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
The 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 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 ElectroMechanical Instrument Cluster (EMIC) for all of the wiper and washer system functions. The EMIC then sends electronic messages to the Front Control Module (FCM) over the Controller Area Network (CAN) data bus requesting the appropriate wiper and washer system operating modes.
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)/Power Distribution Center (PDC) to the wiper on/off relay and the wiper high/low relay in the IPM/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 a high side driver 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 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 EMIC, the FCM, or the electronic message inputs to or outputs from the EMIC or the FCM that control the wiper and washer system operating modes. The most reliable, efficient, and accurate means to diagnose the EMIC 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 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 EMIC 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 EMIC 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 EMIC 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 EMIC 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 EMIC sends an electronic washer switch message to the FCM, then the FCM directs battery current 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 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 EMIC sends an electronic washer switch message to the FCM, then the FCM directs battery current 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.