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MODULE 2–WINDSHIELD WIPERS Topic A. Windshield Wiper System Operation TRACING A WINDSHIELD WIPER CIRCUIT Refer to screen A-3 of your CD-ROM for an example of a wiper circuit schematic. Depressed Park Position A-2 The depressed park feature lowers the wipers so they are out of view when not in use. Types of windshield wiper system functions may include: two or three speed with intermittent wipers. wipe after wash. The wipe after wash function turns the wipers on for a set period of time, usually between six and ten seconds. “Depressed Park.” This feature engages the wiper motor so that it drops the wipers below the windshield trim when they are not in use. When the wiper switch is activated: current is sent to a relay box. A relay may be used to reduce the size of the wires leading into the steering column. a relay sends power to the wiper motor. the activated wiper motor rotates a crank that is connected to the wiper linkages. A-4 Most wiper motors are two- or three-speed motors with an intermittent feature. The amount of power sent to the wiper motor is dependent on the wiper switch setting (HI/MED/LOW). The setting of the switch determines which circuit is used to supply power to the motor. The type of resistor in the circuit is used to adjust the amount of current to the motor, therefore controlling the speed of the motor. For example, when the switch is set to low speed, it uses a circuit with more resistance. When the switch is set to high speed, it uses a circuit with less resistance. Wiper systems are normally open and only operate when the ignition switch is in the ON or ACC position. Power Accessories Program 1 v.5.1–Module 2 © 2003 Inter-Industry Conference On Auto Collision Repair 12 ABS Control Module A-5 The control module helps determine the speed of the windshield wipers when in the intermittent mode. A-6 Resistors can be added to a wiper system to vary the time between wipes. Intermittent wiper operation is generally computer controlled and the time delay may be adjusted according to vehicle speed. For the time delay to be adjusted according to the vehicle speed, the wiper control module receives information from the ABS control module. Once the vehicle is over a specified speed, the wiper delay time decreases to compensate for increased moisture on the windshield. For example on one vehicle, if the speed is greater than 16 km/h (10 mph), the intermittent mode has a range of 0.5 to 18 seconds. However, if speed is less than 16 km/h (10 mph), the intermittent mode has a range of 1 to 36 seconds. Intermittent wiper systems may use a capacitor to provide power to the wiper system. Current flows to the capacitor. Once the capacitor is fully charged, it activates the wiper system. Power Accessories Program 1 v.5.1–Module 2 © 2003 Inter-Industry Conference On Auto Collision Repair Resistors may be added to vary the time between wipes. A resistor is used to vary the amount of time required to saturate the capacitor. More resistance means it will take longer for the capacitor to charge. For example, when switched to a slower speed, current flows through a circuit that has more resistance, thus increasing the time between wiper activation. 13 Rotating Crank A-7 Some primary parts of a wiper system include the wiper switch, wiper linkage, and wiper motor. System parts commonly associated with a wiper assembly include a: motor. wiper. wiper linkage. wiper arm and blade. fuse/relay/resistor. multi-position switch. computer module. A-8 The wiper linkage configuration varies from vehicle-to-vehicle. The wiper arm and linkage configuration: has a centrally located crank that rotates. The rotating crank swings the attached linkage backand-forth, rotating the wiper spindles. The blade arms that are attached to the spindles wipe across the glass. varies from vehicle-to-vehicle or vehicle makerto-vehicle maker. WIPER SYSTEM OPERATION Select the Demonstration Icon found on screen A-8 of your CD-ROM for a video demonstration of how a wiper system operates. Power Accessories Program 1 v.5.1–Module 2 © 2003 Inter-Industry Conference On Auto Collision Repair 14 Topic B. Checking And Diagnosing Mechanical Failures B-3 Some wiper arms require a special removal tool to separate the arm from the pivot. B-1 Inspect wiper arms for bends or damaged to the blade structure. When checking a wiper system for mechanical failures, look for: When removing a wiper arm: bends or breaks in the transmission, or links, between the wipers. stripped or worn splines on the wiper linkage or wiper pivots. This may cause the wipers to knock upon changing direction, the wiper blades to park improperly, or the wipers to slap against the cowl screen or window moldings. bent wiper arms or blade structure. A bend in the blade structure can cause the blades to chatter during operation. loose linkage. corrosion in the computer module. damaged wiper blades. make sure the arms are in the park position. remove the wiper arm pivot cover. remove the nut that holds the wiper to the wiper pivot, if applicable. a special removal tool may be required. For example, some arms may require a two-jaw puller to separate the arm from the pivot. the hood is either opened or closed depending on arm design Some vehicle makers recommend using a specific wiper arm puller and have specific cautions against using a screwdriver or other prying tool. Using a tool other than a wiper arm puller may distort the wiper arm. If there is mechanical damage, the damaged parts may require replacement. This may include removal and replacement (R&R) of the wiper: arm. linkage. Some vehicle makers have special tools that are required for separating wiper linkages. assembly. Some systems do not service linkages alone and may require replacement of the entire wiper linkage assembly. Power Accessories Program 1 v.5.1–Module 2 © 2003 Inter-Industry Conference On Auto Collision Repair 15 B-4 Taping the location of the wiper blade before removal is helpful in realigning the wiper during installation. B-5 Many wiper arms are removed by removing the nut on the wiper arm pivot. Tape may be used to help realign the replacement wiper arms if they have been removed. A strip of tape can be placed at the location of the existing arms on the windshield or backlite. Then, when the wipers are reinstalled, the replacement arms are aligned with the tape. When installing a wiper arm: Ensuring proper alignment of the wiper arms is crucial in preventing damage to the wiper assembly. Misaligned arms may come in contact with each other, bending the wiper arms or damaging the wiper spindles and linkages. Some vehicle makers have a recommendation for the amount of force, or spring tension, applied to the windshield by the wiper arm. If not enough force is applied to the windshield, the effectiveness of the wiper blade will be limited. To measure the force: Power Accessories Program 1 v.5.1–Module 2 © 2003 Inter-Industry Conference On Auto Collision Repair reverse the order of the removal process. make sure that differently sized wiper arms are attached at the proper pivot point to avoid damage during operation. Before removing the wiper arms, a piece of tape marking the right or left wiper is attached to the wiper arm. This ensures that the proper wiper is installed on the proper pivot. wiper arms are run to the mid-wipe position. the blades are removed from the wiper arm. a scale is attached to the wiper arm attaching pin. The amount of force required to lift the wiper arm to the normal working height, or height with the blade attached, is measured. The pressure is measured in Newtons or ounces. If the force is not as specified by the vehicle maker, the wiper arm should be replaced. 16 66mm 40mm B-6 Check vehicle maker specifications for wiper arm positioning measurements. To ensure wiper arms are properly aligned during installation, vehicle makers may provide specific wiper arm measurements. The measurements may include the distance: from the tip of the blade to the cowl. between blades. from the tip of the driver side wiper blade to the A-pillar when the blade is in the outwipe position. B-7 Apply water to the windshield after wiper arm installation to check for proper operation. To check for proper wiper arm installation and operation: Skipping or wiper chatter may be eliminated by: Power Accessories Program 1 v.5.1–Module 2 © 2003 Inter-Industry Conference On Auto Collision Repair run the wipers at slow speed while applying water to the windshield. check for skipping or chattering across the windshield. windshield glass cleaning. blade element cleaning. verifying proper wiper arm pressure. performing a blade element set check. This requires removing the wiper blades from the wiper arms, sighting down the length of the blade element, and making sure the blade is no more than ±15° of centerline. twisting the wiper arm extension rod until the wiper blade “rolls over.” 17 To replace a wiper linkage assembly: remove the wiper arms and cowl cover. disconnect the wire connectors. disconnect the washer hose/drain tubes. remove any nuts and bolts. remove the wiper unit. Topic C. Diagnosing Electronic Problems During installation, make sure that the wiper nuts are torqued to recommended specifications. These recommendations are typically found in the vehicle service manual. If a piece of the wiper linkage is damaged, it is either replaced individually or as an entire linkage assembly. Replacing either individual linkages or the assembly is dependent on the linkage design and vehicle maker recommendations. C-1 Performing a continuity check on a wiper switch typically requires removing the switch from the circuit and testing specific pin locations for resistance readings. One of the steps that is required for diagnosing problems in the wiper electrical system is to check the switch for proper operation. The switch should be checked for continuity with the wiper switch in the: OFF position. INT position. LO position. HI position. washer ON position. If resistance is not as specified in the service manual, the switch should be replaced. Some service manuals provide specific resistance measurements, others do not. For those manuals that do not provide a specific reading, make sure that there is continuity. If there are no specific pin recommendations, do NOT probe individual pins to find continuity. This may damage the switch. Power Accessories Program 1 v.5.1–Module 2 © 2003 Inter-Industry Conference On Auto Collision Repair 18 C-2 Improper voltage to the wiper motor may cause the wipers to operate at improper speeds. C-3 On some vehicles, a diagnostic scan tool may be used to retrieve trouble codes set by a malfunctioning wiper system. Check the motor for proper voltage during operation. To check the motor for proper voltage, a DVOM is connected to the specified terminals. Then, the wipers are run at low or high speed. There is less voltage when the motor is being run at slower speeds compared to running at higher speeds. This number is checked against service manual specifications. Some vehicles have control modules that will set diagnostic trouble codes if there are problems with the wiper system. A scan tool is required to retrieve the trouble code on this particular system. It is also important to check the circuit protection to ensure that it is working properly. While some wiper motors have an internal automatic resetting circuit breaker to protect the motor from circuit overloads, others may have a fuse that, when damaged, must be replaced. DIAGNOSING WIPER SYSTEM PROBLEMS Select the Activity Icon on screen C-3 of your CD-ROM for an interactive exercise on diagnosing wiper system problems. Damaged electronic parts of a wiper system that are typically removed and replaced include the: wiper motor. wiper/washer switch. control module. relay. There are no repair procedures for these parts. Power Accessories Program 1 v.5.1–Module 2 © 2003 Inter-Industry Conference On Auto Collision Repair 19 Topic D. Additional Wiper System Parts To replace a rain sensor: 1. Gently pry the trim cover to remove the cover from the rain sensor module. 2. Remove the trim cover from the rain sensor module. 3. Release the windshield coupler retaining clips. 4. Remove the rain sensor module. 5. Disconnect the electrical connector from the rain sensor module. 6. Reverse procedure for installation. D-1 Rain sensors automatically engage the wiper system when moisture on the windshield is detected. Rain sensors use a control module, part of the sensor, that is located next to the inside rearview mirror to detect moisture on the windshield. The sensor uses infrared beams directed into the windshield at a 45° angle. If the glass is dry, most of the infrared light is deflected back into the sensor by the windshield. When it rains, however, the beams are deflected in different directions by moisture which then engage the wipers. As the number of raindrops increases, the less infrared light makes it back to the sensor, thus increasing the wiper speed. This system can be turned off at the driver’s discretion. Damage to rain sensors may include damaged: moisture sensor. wiring or connectors. D-3 Washer pumps are typically located in the base of the washer fluid reservoir. Washer pumps are: used for spraying washer fluid on the windshield. either outside or contained within the washer fluid reservoir. typically activated by holding in the washer switch. This activates the wipers for a programmed length of time. To determine if there is damage to the rain sensors, continuity and voltage checks are typically performed. Power Accessories Program 1 v.5.1–Module 2 © 2003 Inter-Industry Conference On Auto Collision Repair 20 Wiper Fluid Sensor D-4 Check for leaks or damage to washer fluid hoses. Collision damage may occur to the: hoses. sprayers. pump. wiring that leads to the pump. D-5 The wiper fluid level sensor has a delay feature built into it that prevents the low level message from appearing when the washer fluid sloshes in the reservoir while driving. Some vehicles are equipped with a “Check Washer Fluid” message on the instrument cluster. This circuit operates “open” until fluid reaches a specified low level. Once the specified low level is reached, the circuit closes and the “Check Washer Fluid” warning is displayed. Some wiper fluid sensors have a programmed delay. This prevents the warning from appearing on the instrument cluster due to fluid sloshing while driving. Damaged sensors require removing the connector and removing and replacing the sensor from the washer bottle. The mist feature operation is typically identical to the LOW wiper speed operation. When the switch is pressed, the lower speed wiper operation is started and will continue until one cycle is complete. If the mist feature remains activated, it will continue to operate in the LOW mode. Topic E. Review REVIEW Refer to screens E-1 through E-2 of your CD-ROM for review questions on wiper systems. Power Accessories Program 1 v.5.1–Module 2 © 2003 Inter-Industry Conference On Auto Collision Repair 21