Transcript Chapter 23

Chapter 23
Electrical Accessories
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Windshield Wiper/Washer Systems
• Found on all front
windshields
• Often on rear windshields
• Some vehicles have
headlight wiper/washers
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Windshield Wiper/Washer Systems
• Permanent magnet wiper circuits
– Are the most common design
– Speed is controlled by the placement of the
brushes on the commutator
– Three brushes are used
– Park switch supplies voltage to motor after the
wiper switch is turned off
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Three Brush Motor
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Windshield Wiper Systems (Cont.)
• Electromagnetic field wiper circuits
– Use two fields that are wired in opposite
directions - the shunt field and the series field
– A ground side switch determines the path of
current flow and motor speed
– The shunt field reduces motor speed
– In high speed the shunt field ground has
resistance, reducing current flow
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Three-Speed Motors
• The control switch and resistors determine
motor speed
• For low speed both coils have equal current
flow
• Medium speed sends current flow through
a resistor before the shunt coil
• High speed places a higher resistance in the
shunt field circuit
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Wiper Linkage and Blades
• Several arms and pivots
comprise wiper linkage
• The motor spins and
rotates linkage
• A few systems use two
motors instead of
linkage
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Intermittent Wiper Designs
• Most are controlled by an electronic module
– The module may be mounted on the steering
column or on the wiper motor
• Some vehicles incorporate this function in
the body control module
• A variable resistor is commonly used as an
input
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Intermittent Wiper Control
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Rain Sensing Wipers
• Use a sensor that transmits infrared light
onto windshield surface
• A dry windshield reflects light back to the
sensor
• Water on the windshield reduces the
reflected light
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Rain Sensing Wipers (Cont.)
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Speed-Sensitive Wipers
• Vary the speed or intermittent wiper
interval based on vehicle speed
• Typically controlled by the BCM
• Uses input from the VSS
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Windshield Washers
• Most washer systems use a small electric
pump installed in the fluid reservoir
• A few pump styles operate off of the wiper
motor
• Some vehicles have washers that clean the
headlights
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Washer Reservoir and Pumps
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Headlight Washers
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Common Wiper Concerns
•
•
•
•
•
Poor wiping
No operation
Intermittent operation
Continuous operation
Wipers will not park
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Wiper System Diagnosis
• Diagnosis depends on
type of system
• May need to use a scan
tool to monitor inputs
and output commands
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Washer System Service
• Check for restrictions
in lines and nozzles
• Pumps can be checked
the same as any
electrical circuit
• Pumps are replaced
when defective
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Knowledge Check
• Explain two ways in which wiper motor speeds
are controlled.
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Horn Circuits
•
•
•
•
•
•
Horn
Horn switch
Slip ring
Clockspring
Horn relay
BCM or similar module
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Horn Diagnosis
• Check horn fuse first
• Listen for the horn relay
to “click”
• Test at the relay for
power and circuit
control
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Clock
• Receives power from
fuse panel
• Some clocks have
additional functions as
explained in the vehicle
owner’s manual
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Cigarette Lighter
• Uses a heating element that automatically
releases
• Most vehicles have power outlets
• Outlets appear similar to lighter sockets but
often are rated at lower amperages
• Can be used to power cell phones and other
devices
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Power Outlet
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Blower Motor
• Also called interior fan
• Circulates air inside
passenger
compartment
• May be resistor
controlled or PWM by a
blower or HVAC module
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Resistor Blower Control Circuit
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Blower Resistor
• Contains three or four
resistances wired in
series
• May contain a thermal
limiter
• May be combined with
a blower relay
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Blower Diagnosis
• Determine if inoperative on all speeds or
select speeds
• May have separate high speed relay
• Check for varying voltage at motor
• Open resistors and switches are common
failures
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Blower Diagnosis (Cont.)
• Automatic climate
systems may set DTCs
for blower faults
• Check scan data
• Attempt to command
blower operation
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Knowledge Check
• An interior fan motor only works on high
speed. Technician A says the fan motor is
faulty. Technician B says the blower resistor
may be faulty. Who is correct?
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Cruise Control Systems
• Vacuum Systems
– Was the most common system
– A transducer senses and controls speed
– The servo unit controlled the throttle based on
vacuum input from transducer
– Had an electrical and vacuum brake-activated
switch to disconnect cruise control
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Cruise Control Systems (Cont.)
• Electronic Systems
– Use a control module to move a servo or stepper
motor
– Throttle-by-wire engines do not use separate
cruise control module
– Cruise system uses VSS and brake position sensor
inputs
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Adaptive Cruise Control
•
•
•
•
Maintains speed and distance
Can adjust speed to vehicle in front
Uses laser or radar
If distance decreases between vehicles, the
cruise module can apply the brakes
• Can increase speed once a safe distance is
regained
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Cruise Control System Service
• Perform a visual inspection of the system
– Check cruise indicator lamp operation
– Check vacuum hoses
– Inspect all wiring
– Check the fuses
– Check and adjust linkage cables or chains
– Check brake light operation
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Cruise Control System Service
(Cont.)
• If the system doesn’t work at all
– Check the fuse
– Check the brake light operation
– Check the clutch switch for proper operation
– Check for the presence of vacuum at the servo
– Test control switches and speed sensor
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Check Cruise Control Data
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Sound Systems
• Antenna
– Receives AM and FM
signals
– Should be 31 inches high
• Power Antenna
– Motor raises and lowers
antenna
– Broken cables or
defective motors may be
replaceable
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Sound Systems (Cont.)
• Satellite Radio
– Provides coast-tocoast coverage
– Cannot penetrate
buildings or tunnels
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Sound Systems (Cont.)
• Phone and Multimedia
Systems
– Cell phone (Bluetooth)
connectivity
– DVD entertainment
systems
– USB and MP3
connections
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Sound System Diagnosis
• Test the system outside, not in a building
• Check the vehicle’s ignition system if noise is
heard on the radio
• Verify that all wires are properly shielded
• Check speakers for proper mounting
• Always use the manufacturer’s diagnostic
procedures
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Speaker Output Testing
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Telematics
• The transmission of information
• Common automotive applications include:
– Tire pressure monitoring
– Satellite navigation
– Mobile Internet
– Airbag deployment notification
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Telematics (Cont.)
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Voice Activation
• Allows for control of
various systems, such as
phone and navigation
• A microphone picks up
the driver’s voice
• A module translates the
command into an action
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Navigation Systems
• May use GPS or DVDs
for data
• May display current
traffic and weather
conditions
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Vehicle Tracking Systems
• Tracks vehicle at
owner’s request
• May notify if airbags
deploy
• May allow remote
unlocking and starting
• Vehicle data available
on smartphone
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Power Lock Systems
• Reversible motors
• Power and ground supplied through the
switch
• May automatically lock doors when
transmission is shifted from park or at a
certain speed
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Power Trunk Release
• Uses a switch
and a solenoid
• Voltage applied
through the
switch to the
solenoid
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Diagnosis
• If none of the locks work, check the circuit
protection device
• If system only locks or unlocks, check the
relays if equipped
• If only one door operates, check that door
actuator
• Perform a switch test
• Check trunk release fuse first, then switch
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Power Windows
•
•
•
•
•
Master control switch
Individual control switches
Individual window drive motors
Express-down module
Lock-out or disable switch
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Power Window Motor
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Circuit Operation
• Reversible motors operate when power and
ground are applied
• Express windows use a module to control
window movement
• Controlled by the BCM and may need reenabled if power is lost
• Some systems have obstacle sensing to
prevent closing
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Power Window System
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Diagnosis
• Determine if whole system or part is not
working
• Use the system wiring schematic to determine
the proper diagnostic procedure
• Test the circuit breaker for the presence of
voltage on both sides
• Use a jumper wire to test the motor
• Use a voltmeter or scan tool to check the
switches
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Scan Tool Diagnosis
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Knowledge Check
• Only the driver’s door window will operate.
Technician A says the power window fuse may
be open. Technician B says the window
lockout switch may be on. Who is correct?
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Power Seat Types
• Two-way
– Moves the seat forward and backward
• Four-way
– Moves the seat forward, backward, up, and
down
• Six-way
– Moves the seat forward, backward, up,
down, front tilt, and rear tilt
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Diagnosis
• Visually inspect wires and connections
• Test for available voltage at the switch
• Use a continuity chart, if available, to
check the switch
• If the switch tests good, test the motors
• Unusual noises can be caused by the
motor, transmission, or cables
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Power Seat Circuit
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Other Seat Options
• Temperature-controlled seats
– Can be either heated or cooled
• Power lumbar supports
– Inflate or deflate an air bladder for spine support
• Memory seats
– Automatic repositioning based on driver
preference
• Adaptive and active seating
– Provides discrete stimulation to prevent fatigue
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Power Mirror System
• A “joystick” allows control of both mirrors
from one switch
• Dual motor drive assemblies are located in
each mirror assembly
• Some systems automatically adjust for parking
maneuvers
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Inside Mirrors
• Some automatically
adjust for day/night
driving
• May have a compass
display
• Electrochromic mirrors
adjust reflection based
on intensity of light
striking the mirror
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Rear-Window Defroster and Heated
Mirror Systems
• Rear-window defroster heats surface
– Circuit has a switch, relay, and heating element
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Diagnosis
• Common problem is damage to defroster grid
• When a segment of the grid is damaged, the
circuit opens
• This leaves sections unheated
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Other Accessories
• Adjustable pedals
– Electric motor moves both pedals up to about
three inches
– May be part of memory seat function
• Heated windshield
– Uses a micro-thin coating within laminate
– Directs generator output to windshield
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Other Accessories (Cont.)
•
•
•
•
Moon (sun) roof
Retractable hardtops
Night vision
iDrive
– Used to control climate, entertainment, and all
active driving control functions
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Other Accessories (Cont.)
• Blind spot detection
– Uses radar sensors mounted on bumper
• Rear view cameras
– Displays view on dash mounted screen
• Parking assist
– Radar sensors detect close objects
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Blind Spot Detection
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Rear View Cameras
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Other Accessories (Cont.)
• Self-parking
– On vehicles with electric
steering
• Navigation system
• Vehicle tracking system
• Voice activation system
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Security and Anti-Theft Systems
• Pass-Key System
– Uses a special resistance or transponder key
• Keyless Entry System
– May use a keypad mounted on the door or a
remote key fob
• Smart Keys
– Can lock/unlock doors, allow engine start
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Lane Departure
• Use cameras to detect
position in lane
• Warnings alert the
driver the vehicle is
wandering
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Garage Door Opening
• Programmable garage
door opening remote
• May also activate gates,
home security systems,
and other transmitter
operated devices
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Locks and Keys
• Many vehicles use
special keys which
communicate with
antitheft systems
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Smart Keys
• Used with push button
start systems
• Key must be inside the
vehicle for the engine to
start
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Keyless Entry
• Allows access without a
traditional key
• May use remote key fob
• Some vehicles use a
keypad
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Alarm Systems
• Can be active or passive
• Passive systems switch on
automatically
• Active systems are activated
with remote, keypad, key, or
switch
• If a switch is activated the
alarm sounds
• Can prevent the engine from
starting
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