[ppt]lighting and wiring fundamentals - higher ed ebooks ... · web viewlighting and wiring...
TRANSCRIPT
© © 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
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
© © 2012 Delmar, Cengage Learning
Lighting• Light bulbs
– Often called lamps– Electricity flows through filaments– Filament provides a resistance to electron flow
• It heats up and glows, causing light
© © 2012 Delmar, Cengage Learning
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
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
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
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
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
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
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