Download module 2–windshield wipers

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