Transcript 1133612318_430029x

Chapter 20
Lighting Systems
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Lighting Systems
• Provides interior and
exterior illumination
• Some lighting is
regulated by federal
laws
• Automotive bulbs are
electrically operated
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duplicated, or posted to a publicly accessible website, in whole or in part.
Incandescent Lamps
• A lamp generates heat and light as current
flows through the filament
• Filament vacuum sealed in glass envelope
• Lamps are normally single filament or double
filament
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© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied,
duplicated, or posted to a publicly accessible website, in whole or in part.
Headlights
• Have become integral part of vehicle styling
• Must have low and high beam lights
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Sealed-Beam Headlights
• An air-tight light and
reflector assembly
• May contain low, high,
or both headlight
filaments
• Made obsolete by
halogen bulbs and
composite light
assemblies
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duplicated, or posted to a publicly accessible website, in whole or in part.
Halogen Lamps
• Halogen identifies a group of nonmetallic
elements, including chlorine, fluorine, and
iodine
• Most halogen lamps filled with iodine vapor
• Tungsten filament can withstand higher
temperature because of the halogen
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Composite Headlights
• Use a replaceable
bulb
• Improves
aerodynamics, fuel
economy, and
vehicle styling
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Cylindrical Housings
• Many headlights have cylindrical bulb housings
• Enables the light beam to be projected without
much scattering
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HID Headlights
•
•
•
•
•
Also called xenon headlamps
Use gas-discharge lamps
Electronically controlled
Use an electric arc instead of a filament
Use high-voltage to jump gap and about 80
volts to maintain
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Halogen Compared to Xenon
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Bi-Xenon Lights
• Some vehicles use
xenon lamps for high
and low beams
• Use an additional
halogen lamp for flashto-pass
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duplicated, or posted to a publicly accessible website, in whole or in part.
LED Headlights
• LED benefits:
– Do not require vacuum or high voltage
– Use up to 40% less power
– Provide whiter light than xenon
– Environmentally friendly
– Longer operating life
– More shock resistant
– Reduce glare perception
– Smaller size which provides more flexibility
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LED Headlights (Cont.)
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Daytime Running Lights (DRLs)
• Added safety feature
• Headlights connected in
series when the ignition
switch is on and
headlights are off
• When headlights are
turned on normal
operation returns
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duplicated, or posted to a publicly accessible website, in whole or in part.
Auxiliary Lights
• Fog lights are common
auxiliary lights
• Mounted low to cut
under fog
• Normally turned off if
high-beams are on
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duplicated, or posted to a publicly accessible website, in whole or in part.
Knowledge Check
• Technician A says LED headlights require highvoltage to operate. Technician B says HID
headlights use a special high-voltage filament
to generate a brighter light. Who is correct?
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duplicated, or posted to a publicly accessible website, in whole or in part.
Headlight Switches
• Controls most exterior lighting
• Instrument panel (IP) lights come on when
switch is in park or headlight position
• IP light brightness may be controlled by
rheostat in headlight switch
• The system can be power-side or groundside controlled
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duplicated, or posted to a publicly accessible website, in whole or in part.
Headlight Switches (Cont.)
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Dimmer Switches
• Allows driver to switch between high- and
low-beams
• Connected in series with headlight circuit
• Typical dimmer switch
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Flash-to-Pass
• Most steering-column-mounted
dimmer switches have flash-to-pass
• Illuminates the high-beams even with
headlights off
• Completes a circuit to the high-beam
headlights
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duplicated, or posted to a publicly accessible website, in whole or in part.
Automatic Light Systems
• Light-sensitive, automatic, on-off control
• Uses a photocell sensor/amplifier
• Manual headlight switch operation
overrides automatic setting
• High-beam detection system turn highbeams on and off
– Forward looking light sensor detects conditions
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duplicated, or posted to a publicly accessible website, in whole or in part.
Automatic Headlight Switch
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duplicated, or posted to a publicly accessible website, in whole or in part.
Adaptive Headlights
•
•
•
•
•
Inputs from steering system and vehicle speed
Aims headlights in direction of turning
One design uses motors to position headlights
Second design uses extra turning lamps
Adaptive system may use GPS data
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duplicated, or posted to a publicly accessible website, in whole or in part.
Headlamp Service
• Headlamp failures are usually caused by burned out
bulbs
• Check for voltage at the bulb before replacing it
• If more than one lamp is not working, carefully check
the circuit
• If the voltage regulator is defective, the high voltage
will cause lamps to burn out prematurely
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duplicated, or posted to a publicly accessible website, in whole or in part.
Restoring Headlight Lenses
• Over time the
polycarbonate
deteriorates, clouding
the lens
• Polishing may restore
the lens
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duplicated, or posted to a publicly accessible website, in whole or in part.
Headlight Replacement
• Sealed beam lights are
secured with a clip or
retaining ring
• Accessing the light may
require removing
bumper covers or inner
fender liners
• Do not touch the glass
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HID Diagnosis and Service
• Turning headlight switch on powers the HID
transformer
• Bi-xenon system uses a shutter to redirect
light
• A delay before full illumination is normal
• Blue to white light is normal
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HID Bulb Replacement
•
•
•
•
•
HID bulbs do not suddenly stop working
As bulb wears it will shut off and turn on
Will become more frequent
Increases wear on the transformer
If lights are flickering, the transformer should
be replaced with the bulbs
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HID Transformer
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Headlight Adjustment
• Before adjusting headlights:
– Vehicle must be on a level floor
– Remove ice, snow, or mud
– Try to adjust with fuel tank half full
– Check vehicle ride height
– Inflate tires to specifications
– Wheel alignment should be correct
– Settle the suspension before adjustment
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Headlight Adjustment (Cont.)
• Many vehicles have built-in bubble levels for
headlight adjustment
• Headlight aiming equipment uses a split
mirror system and levels for adjustment
• If neither are available, a screen can be used
to determine headlight accuracy
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Headlight Adjustment (Cont.)
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duplicated, or posted to a publicly accessible website, in whole or in part.
Auto-Leveling Headlights
• Found on xenon equipped vehicles
• Keeps headlight aim within a certain range
regardless of load and driving conditions
• Each headlight has a leveling motor
• Uses input from front and rear suspension
• Diagnosed with a scan tool
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Knowledge Check
• What type of tools and equipment may be
necessary to adjust headlight aim?
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Automatic Headlight
System Diagnosis
• Inspect for any obstruction of the photo
cell
• Proper photo cell alignment is necessary
• Follow the manufacturer’s testing
procedures
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duplicated, or posted to a publicly accessible website, in whole or in part.
Adaptive Headlight Diagnosis
• Controlled by a headlamp control module
• Monitor inputs with a scan tool
– Data used from ECM, TCM, EBCM, and BCM
• Headlamp module calculates desired angle
• Module can also monitor motor control
circuits
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duplicated, or posted to a publicly accessible website, in whole or in part.
Basic Lighting System Diagnosis
• Bulbs are quickly checked with ohmmeter or
powered test light
• Inspect for corroded or loose wiring
• Many exterior lights are exposed to climate
and weather conditions that can damage
wiring and sockets
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duplicated, or posted to a publicly accessible website, in whole or in part.
Checking Bulb Resistance
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duplicated, or posted to a publicly accessible website, in whole or in part.
Scan Tool Diagnostics
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Other Light Bulbs
• Most designs prevent
using incorrect bulb
type
• May be several types
within the design
• Bulbs have trade
numbers
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duplicated, or posted to a publicly accessible website, in whole or in part.
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duplicated, or posted to a publicly accessible website, in whole or in part.
Bulb Replacement
• Make sure the replacement is the correct
bulb
• Inspect the bulb socket
• Often removal of light assembly is necessary
• Do not remove lenses from light assemblies
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duplicated, or posted to a publicly accessible website, in whole or in part.
Bulb Replacement (Cont.)
• Gain access the bulb
• Remove the bulb and
inspect the socket
• Replace with the
correct bulb
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duplicated, or posted to a publicly accessible website, in whole or in part.
Light Circuits
• Single filament bulbs use two wires
• Double filament bulbs will have two hot wires
and a ground
• Light circuits can be either power or ground
controlled
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duplicated, or posted to a publicly accessible website, in whole or in part.
Rear Exterior Lights
• Rear lights include
– Brake lights
– Taillights
– Turn signal / hazard
lights
– Back-up lights
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duplicated, or posted to a publicly accessible website, in whole or in part.
Turn, Stop, and
Hazard Warning Lights
•
•
•
•
Each system has a switch to control operation
Turn signals only powered with key on
Stop and hazard lights powered with key off
Turn signal and hazard lights may be part of
multifunction switch
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duplicated, or posted to a publicly accessible website, in whole or in part.
Flashers
• Used by turn signal
and hazard systems
• Older vehicles use
temperature sensitive
bi-metallic strip
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duplicated, or posted to a publicly accessible website, in whole or in part.
Electronic Flasher
• Modern flashers are
electronic
• An inoperative turn
signal bulb generally
causes a different
flashing rate
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duplicated, or posted to a publicly accessible website, in whole or in part.
Brake (Stop) Lights
• Controlled by brake light switch normally
mounted on brake pedal bracket
• All late model vehicles have a center highmounted stop light (CHMSL)
• Brake light switch input is also used for
cruise control, ABS, and traction control
systems
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duplicated, or posted to a publicly accessible website, in whole or in part.
Adaptive Brake Lights
• Can operate under standard illumination
during normal braking
• Under intense braking or ABS intervention,
additional lights are lit
• Increases the size of brake lights
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duplicated, or posted to a publicly accessible website, in whole or in part.
Brake Light Switches
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Brake Light Circuit
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LED Lights
• LED and neon lights
used for some brake,
tail, and turn signal
lights
• LED illuminate faster,
consume less power,
and last longer than
incandescent lights
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duplicated, or posted to a publicly accessible website, in whole or in part.
Back-Up Lights
• Activated by the parkneutral switch on
automatic
transmissions
• Manual transmission
have separate reverse
light switch
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duplicated, or posted to a publicly accessible website, in whole or in part.
Knowledge Check
• Technician A says a burned out bulb can cause
the turn signals to not blink properly.
Technician B says installing an incorrect bulb
may cause the turn signals to not blink
correctly. Who is correct?
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duplicated, or posted to a publicly accessible website, in whole or in part.
Interior Light Assemblies
• Engine compartment
light
• Glove box light
• Luggage compartment
light
• Trunk lid light
• Vanity light
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duplicated, or posted to a publicly accessible website, in whole or in part.
Courtesy Lights
• Provides light inside the vehicle
• Operated by doors, headlight switch, or
separate switch
• Often tied into keyless entry and/or alarm
• Map lights usually independent of courtesy
lights
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duplicated, or posted to a publicly accessible website, in whole or in part.
Illuminated Entry System
• Illuminated lock cylinders
• Most have an electronic actuator module
• Activated by lifting outside door handle or
keyless entry
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duplicated, or posted to a publicly accessible website, in whole or in part.