Post on 31-Mar-2015
© © 2012 Delmar, Cengage Learning
Lighting and Wiring Fundamentals
Chapter 32
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Objectives• Describe differences between wire and cable• Explain the fundamentals of operation of
automotive lighting and wiring• List when different circuit protection devices
would be used
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Introduction• Lights and wiring:
– Can be a complicated system
• Electricity is provided through:– Wiring
– Cables
– Fibers
• Circuit protection devices:– Fuses
– Circuit breakers
– Fusible links
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Wire and Cable• Chemicals, corrosion, vibration, and heat
– Damage wiring
• Primary and secondary wires– Primary wiring: low-voltage wiring
– Secondary wiring: ignition wiring
– American Wire Gauge (AWG): describes the size of wire or cable used
– Cables: large wires that allow more electrical current to flow
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Circuit Protection Devices• Fuse: protective device designed to melt when
the flow of current becomes to high– Replaceable fuses
• Blade type• Ceramic type• Glass tube cartridge type
– Fuse link • Length of wire smaller in diameter than the wire it
is connected to
© © 2012 Delmar, Cengage Learning
© © 2012 Delmar, Cengage Learning
Circuit Protection Devices (cont'd.)
• Circuit breakers– Used in automobiles: usually self-resetting
• Breaker “trips” and then resets
– Bimetal strip: two metal strips with different expansion rates
• Higher expansion metal will become longer and will break the switch contact
• Contact is reestablished when it cools
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Lighting• Light bulbs
– Often called lamps
– Electricity flows through filaments
– Filament provides a resistance to electron flow • It heats up and glows, causing light
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Headlamps• Headlight and headlamp
– Terms are used interchangeably
– Intensity of a headlamp: rated in candlepower
• Sealed-beam headlamp construction– Have an inner glass or plastic reflector surface
• Type I lamp: high beam only• Type II lamp: both low and high beams
• Halogen lamps – Produce a 25% higher output of “whiter” light
– Conventional sealed beam or composite
© © 2012 Delmar, Cengage Learning
© © 2012 Delmar, Cengage Learning
Headlamps (cont'd.)• High-intensity discharge lamps
– Provide three times more light than conventional halogen headlamps
• Adaptive headlights – Can swivel up to 15 degrees right or left
• Headlight switch– Multifunction on steering column or mounted on
dash panel
– Typically two or three positions besides the off position
© © 2012 Delmar, Cengage Learning
© © 2012 Delmar, Cengage Learning
Headlamps (cont'd.)• Dimmer switch
– Changes headlights from low to high beam
• Automatic headlight dimmer– Detects oncoming cars
• Courtesy lights– Interior dome and underdash lights
• Headlight wiring– Many use grounded electrical systems
– Daytime running lights: powered when engine is running
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Headlamps (cont'd.)• Automatic headlights
– Use a light-sensitive photocell sensor
– Delay shutoff keeps lights on for a short period
• Flash to pass– Raising turn signal activates high beams
• Driving lights and fog lamps – Occasionally installed as original equipment
– Normal lights do not work well in fog• Fog reflects light back at the driver
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Taillights• Taillight bulbs
– Come in many sizes and types
– Are usually ground through the base to the bulb socket
• Light socket: usually grounded to frame
• Newer vehicles– Bulbs have a plastic socket mounted in plastic
housings
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Light Bulb Identification • Miniature lights: bulbs smaller than headlamps
– Correct replacement bulb must be used• Otherwise, circuit problems could result
• Bulbs are numbered by the ANSI– Identification number is the bulb trade number
• Stoplight switch– Activated by a mechanical switch on brake pedal
• Taillights and brake lights– Taillight bulbs have one or two filaments
• Activated by brakes
© © 2012 Delmar, Cengage Learning
© © 2012 Delmar, Cengage Learning
Fiber Optics• Light can be transmitted through a special plastic
called polymethacrylate– Fiber-optic strands illuminate indicator on fender
• LED and neon lights – Energy efficient, long lasting, and compact
• Center high-mount stop lamps– Row of LEDs, filament bulb, or a neon tube
• Adaptive brake lights – Intensity increases as driver pushes on brake
pedal
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Turn Signals• Turn signal circuit components
– Switch
– Signal flasher
– Two indicator bulbs
– Stoplight filaments or rear stoplight bulbs
– Two bulbs in the front of the vehicle
• Turn signal – Usually part of a multifunction switch in the
steering column
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Signal Flasher Operation• Turn signal flashers
– Turn signals and safety hazards
– Mechanical or automatic
• Electronic turn signal flashers – Operate when a transistor is triggered on and off
• Transistor: electronic switch with no moving parts
– Operate turn signals and hazard warning lights
• Relay turn signals– Mechanical
– Electronic
© © 2012 Delmar, Cengage Learning
© © 2012 Delmar, Cengage Learning
Hazard Flashers• Required on cars manufactured after 1967
– Circuit is powered directly from the battery
• Emergency flasher switch locations– Side of the steering column
– Dash panel
– Glove box
• Emergency warning systems – Use a variable load flasher
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Back-Up Lights• Operation
– Key is on
– Transmission selector is moved to R position
– Lights at the rear of the vehicle are illuminated
• Provide a white light that allows a driver to see – Provides a warning to other drivers
• Some vehicles use the same fuse for turn signals and back-up lights– Current is supplied from the fuse panel to the
back-up light switch
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Wipers and Horn• Windshield wiper motor
– Wiper circuit has fuse or circuit breaker and wiper switch
– Electromagnetic wiper motors: two brushes on armature
– Typical permanent magnet motor: three brushes
• Intermittent wipers – Allow variations in the time interval
• Rain-sensing: begin automatically when water sensed
• Speed-sensitive: controlled with sensor input
© © 2012 Delmar, Cengage Learning
© © 2012 Delmar, Cengage Learning
Wipers and Horn (cont'd.)• Windshield washer
– Components• Reservoir • Switch and pump• Washer nozzles• Hoses and connections
• Types and features– Rear window wiper-washer
– Headlight wiper-washers
– Windshield washer low-fluid indicator
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Wipers and Horn (cont'd.)• Horn circuit components
– Horn
– Fuse and wiring
– Horn switch
– Relay
• Dashboard is called an instrument panel– Combined analog and digital displays
• Electric gauges – Thermal/bimetal gauges, magnetic gauges, and
digital panel gauges
© © 2012 Delmar, Cengage Learning
© © 2012 Delmar, Cengage Learning
Miscellaneous Gauges• Several gauges are on the instrument panel
– Speedometer/odometer
– Tachometer
– Engine coolant temperature gauge
– Engine oil pressure gauge
– Fuel level gauge
– Lamp-out warning light
– Other warning lights
– Other electrical accessories
© © 2012 Delmar, Cengage Learning