Download Lighting and Wiring Fundamentals

Lighting and Wiring
Fundamentals
Chapter 32
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning
Introduction
• Lights and wiring:
– Can be a complicated system
• Electricity is provided through:
– Wiring
– Cables
– Fibers
• Circuit protection devices:
– Fuses
– Circuit breakers
– Fusible links
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning
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
© © 2012 Delmar, Cengage Learning