© © 2012 Delmar, Cengage Learning Lighting and Wiring Fundamentals Chapter 32.

© © 2012 Delmar, Cengage Learning

Lighting and Wiring Fundamentals

Chapter 32


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


Introduction• Lights and wiring:

– Can be a complicated system

• Electricity is provided through:– Wiring

– Cables

– Fibers

• Circuit protection devices:– Fuses

– Circuit breakers

– Fusible links


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


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



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


Lighting• Light bulbs

– Often called lamps

– Electricity flows through filaments

– Filament provides a resistance to electron flow • It heats up and glows, causing light


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



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



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


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


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


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



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


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


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



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


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


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



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


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



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 Lighting and Wiring Fundamentals Chapter 32.

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