© © 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