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: Electricity is provided through: 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 Sealed-beam headlamp construction 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 Adaptive headlights 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 Automatic headlight dimmer 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 Flash to pass 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 Newer vehicles 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 Turn signal 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 Intermittent wipers 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