Transcript measuring systems and tools

56
LIGHTING AND
SIGNALING CIRCUITS
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
All Rights Reserved
56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-1 Dual-filament (double-contact) bulbs contain both a low-intensity filament for
taillights or parking lights and a high-intensity filament for brake lights and turn signals. Bulbs come
in a variety of shapes and sizes. The numbers shown are the trade numbers.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-2 Bulbs that have the same trade number have the same operating voltage and
wattage. The NA means that the bulb uses a natural amber glass ampoule with clear turn signal
lenses.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 Bulbs that have the same trade number have the same operating voltage and
wattage. The NA means that the bulb uses a natural amber glass ampoule with clear turn signal
lenses.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 (continued) Bulbs that have the same trade number have the same operating
voltage and wattage. The NA means that the bulb uses a natural amber glass ampoule with clear
turn signal lenses.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 (continued) Bulbs that have the same trade number have the same operating
voltage and wattage. The NA means that the bulb uses a natural amber glass ampoule with clear
turn signal lenses.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 (continued) Bulbs that have the same trade number have the same operating
voltage and wattage. The NA means that the bulb uses a natural amber glass ampoule with clear
turn signal lenses.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 (continued) Bulbs that have the same trade number have the same operating
voltage and wattage. The NA means that the bulb uses a natural amber glass ampoule with clear
turn signal lenses.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 (continued) Bulbs that have the same trade number have the same operating
voltage and wattage. The NA means that the bulb uses a natural amber glass ampoule with clear
turn signal lenses.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 (continued) Bulbs that have the same trade number have the same operating
voltage and wattage. The NA means that the bulb uses a natural amber glass ampoule with clear
turn signal lenses.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 (continued) Bulbs that have the same trade number have the same operating
voltage and wattage. The NA means that the bulb uses a natural amber glass ampoule with clear
turn signal lenses.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 (continued) Bulbs that have the same trade number have the same operating
voltage and wattage. The NA means that the bulb uses a natural amber glass ampoule with clear
turn signal lenses.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 (continued) Bulbs that have the same trade number have the same operating
voltage and wattage. The NA means that the bulb uses a natural amber glass ampoule with clear
turn signal lenses.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
All Rights Reserved
56 LIGHTING AND SIGNALING CIRCUITS
Chart 56-1 (continued) Bulbs that have the same trade number have the same operating
voltage and wattage. The NA means that the bulb uses a natural amber glass ampoule with clear
turn signal lenses.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
REAL WORLD FIX: Weird
Problem—Easy Solution A
General Motors minivan had the
following electrical problems.
• The turn signals flashed rapidly
on the left side.
• With the ignition key off, the
lights-on warning chime sounded
if the brake pedal was depressed.
• When the brake pedal was
depressed, the dome light came
on.
All of these problems were caused
by one defective 2057 dualfilament bulb, as shown in FIGURE 56–3.
Apparently, the two filaments
were electrically connected when
one filament broke and then
welded to the other filament. This
caused the electrical current to
feed back from the brake light
filament into the taillight circuit,
causing all the problems.
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James Halderman
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Figure 56-3 Close-up a 2057 dual-filament (double-contact) bulb that failed. Notice that the top
filament broke from its mounting and melted onto the lower filament. This bulb caused the dash
lights to come on whenever the brakes were applied.
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Figure 56-4
connected.
Corrosion caused the two terminals of this dual-filament bulb to be electrically
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Figure 56-5 Often the best diagnosis is a thorough visual inspection. This bulb was found to be
filled with water, which caused weird problems.
Automotive Technology, Fifth Edition
James Halderman
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Figure 56-6 This single-filament bulb is being tested with a digital multimeter set to read
resistance in ohms. The reading of 1.1 ohms is the resistance of the bulb when cold. As soon as
current flows through the filament, the resistance increases about 10 times. It is the initial surge of
current flowing through the filament when the bulb is cool that causes many bulbs to fail in cold
weather as a result of the reduced resistance. As the temperature increases, the resistance
increases.
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Figure 56-7 Typical brake light and taillight circuit showing the brake switch and all of the related
circuit components.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
FREQUENTLY ASKED QUESTION: Why Are LEDs
Used for Brake Lights? Light-emitting diode (LED)
brake lights are frequently used for high-mounted
stop lamps (CHMSLs) for the following reasons.
1. Faster illumination. An LED will light up to 200
milliseconds faster than an incandescent bulb, which
requires some time to heat the filament before it is
hot enough to create light. This faster illumination
can mean the difference in stopping distances at 60
mph (100 km/h) by about 18 ft (6 m) due to the
reduced reaction time for the driver of the vehicle
behind.
2. Longer service life. LEDs are solid-state devices
that do not use a filament to create light. As a result,
they are less susceptible to vibration and will often
last the life of the vehicle.
NOTE: Aftermarket replacement LED bulbs that are
used to replace conventional bulbs may require the
use of a different type of flasher unit due to the
reduced current draw of the LED bulbs. - SEE
FIGURE 56–8.
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-8 A replacement LED taillight bulb is constructed of many small, individual lightemitting diodes.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-9 The typical turn signal switch includes various springs and cams to control the switch
and to cause the switch to cancel after a turn has been completed.
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-10 When the stop lamps and turn signals share a common bulb filament, stop light
current flows through the turn signal switch.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-11 When a right turn in signaled, the turn signal switch contacts send flasher current
to the right-hand filament and brake switch current to the left-hand filament.
Automotive Technology, Fifth Edition
James Halderman
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Figure 56-12
Two styles of two-prong flasher units.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-13 A hazard warning flasher uses a parallel resistor across the contacts to provide a
constant flashing rate regardless of the number of bulbs used in the circuit.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
FREQUENTLY ASKED
QUESTION: How Do You Tell
What Type of Flasher Is Being
Used? The easiest way to know
which type of flasher can be used
is to look at the type of bulb used
in the tail lamps and turn signals.
If it is a “wedge” style (plastic
base, flat and rectangular), the
vehicle has an electronic flasher.
If it is a “twist and turn” bayonetstyle (brass base) bulb, then
either type of flasher can be used.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
FREQUENTLY ASKED
QUESTION: Why Does the
Side-Marker Light Alternately
Flash? A question that service
technicians are asked frequently
is why the side-marker light
alternately goes out when the
turn signal is on, and is on when
the turn signal is off. Some
vehicle owners think that there is
a fault with the vehicle, but this is
normal operation. The sidemarker light goes out when the
lights are on and the turn signal
is flashing because there are 12
volts on both sides of the bulb
(see points X and Y in - FIGURE
56–14).
Normally, the side-marker light
gets its ground through the turn
signal bulb.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-14 The side-marker light goes out whenever there is voltage at both points X and Y.
These opposing voltages stop current flow through the side-marker light. The left turn light and left
park light are actually the same bulb (usually 2057) and are shown separately to help explain how
the side-marker light works on many vehicles.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-15 Typical headlight circuit diagram. Note that the headlight switch is represented by a
dotted outline indicating that other circuits (such as dash lights) also operate from the switch.
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-16
A typical four-headlight system using sealed beam headlights.
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-17 A typical composite headlamp assembly. The lens, housing, and bulb sockets are
usually included as a complete assembly.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
TECH TIP: Diagnose Bulb
Failure Halogen bulbs can fail
for various reasons. Some causes
for halogen bulb failure and their
indications are as follows:
• Gray color. Low voltage to bulb
(check for corroded socket or
connector)
• White (cloudy) color. Indication
of an air leak
• Broken filament. Usually caused
by excessive vibration
• Blistered glass. Indication that
someone has touched the glass
NOTE: Never touch the glass
(called the ampoule) of any
halogen bulb. The oils from your
fingers can cause unequal heating
of the glass during operation,
leading to a shorter-than-normal
service life.
- SEE FIGURE 56–18.
Automotive Technology, Fifth Edition
James Halderman
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Figure 56-18
glass.
Handle a halogen bulb by the base to prevent the skin’s oil from getting on the
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-19 The igniter contains the ballast and transformer needed to provide high-voltage
pulses to the arc tube bulb.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
FREQUENTLY ASKED
QUESTION: What Is the
Difference Between the
Temperature of the Light and
the Brightness of the Light?
The temperature of the light
indicates the color of the light.
The brightness of the light is
measured in lumens. A standard
100 watt incandescent light bulb
emits about 1,700 lumens. A
typical halogen headlight bulb
produces about 2,000 lumens,
and a typical HID bulb produces
about 2,800 lumens.
Automotive Technology, Fifth Edition
James Halderman
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Figure 56-20 HID (xenon) headlights emit a whiter light than halogen headlights and usually
look blue compared to halogen bulbs.
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James Halderman
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WARNING: Always adhere to
all warnings because the
highvoltage output of the ballast
assembly can cause personal
injury or death.
Automotive Technology, Fifth Edition
James Halderman
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Figure 56-21 LED headlights usually require multiple units to provide the needed light as seen on
this Lexus LS600h.
Automotive Technology, Fifth Edition
James Halderman
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Figure 56-22
Typical headlight aiming diagram as found in service information.
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Figure 56-23
accurate.
Many composite headlights have a built-in bubble level to make aiming easy and
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-24
travel.
Adaptive front lighting systems rotate the low-beam headlight in the direction of
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-25 A typical adaptive front lighting system uses two motors: one for the up and down
movement and the other for rotating the low-beam headlight to the left and right.
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James Halderman
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Figure 56-26
system.
Typical dash-mounted switch that allows the driver to disable the front lighting
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
TECH TIP: Checking a Dome Light Can Be Confusing If
a technician checks a dome light with a test light, both sides
of the bulb will “turn on the light” if the bulb is good. This will
be true if the system’s “ground switched” doors are closed and
the bulb is good. This confuses many technicians because they
do not realize that the ground will not be sensed unless the
door is open.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-27 Typical daytime running light (DRL) circuit. Follow the arrows from the DRL module
through both headlights. Notice that the left and right headlights are connected in series, resulting
in increased resistance, less current flow, and dimmer than normal lighting. When the normal
headlights are turned on, both headlights receive full battery voltage, with the left headlight
grounding through the DRL module.
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-28 Most vehicles use positive switching of the high- and low-beam headlights. Notice
that both filaments share the same ground connection. Some vehicles use negative switching and
place the dimmer switch between the filaments and the ground.
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-29 A typical courtesy light doorjamb switch. Newer vehicles use the door switch as an
input to the vehicle computer and the computer turns the interior lights on or off. By placing the
lights under the control of the computer, the vehicle engineers have the opportunity to delay the
lights after the door is closed and to shut them off after a period of time to avoid draining the
battery.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
Figure 56-30 An automatic dimming mirror compares the amount of light toward the front of the
vehicle to the rear of the vehicle and allies a voltage to cause the gel to darken the mirror.
Automotive Technology, Fifth Edition
James Halderman
© 2011 Pearson Education, Inc.
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56 LIGHTING AND SIGNALING CIRCUITS
FREQUENTLY ASKED
QUESTION: What Is the
Troxler Effect? The Troxler
effect, also called Troxler fading,
is a visual effect where an image
remains on the retina of the eye
for a short time after the image
has been removed. The effect was
discovered in 1804 by Igney Paul
Vital Troxler (1780–1866), a
Swiss physician. Because of the
Troxler effect, headlight glare can
remain on the retina of the eye
and create a blind spot. At night,
this fading away of the bright
lights from the vehicle in the rear
reflected by the rearview mirror
can cause a hazard.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
TECH TIP: The Weirder the
Problem, the More Likely It Is
a Poor Ground Connection
Bad grounds are often the cause
for feedback or lamps operating
at full or partial brilliance. At first
the problem looks weird because
often the switch for the lights that
are on dimly is not even turned
on. When an electrical device is
operating and it lacks a proper
ground connection, the current
will try to find ground and will
often cause other circuits to work.
Check all grounds before
replacing parts.
Automotive Technology, Fifth Edition
James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
TAILLIGHT BULB REPLACEMENT 1 The driver noticed that the taillight fault indicator (icon) on
the dash was on any time the lights were on.
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TAILLIGHT BULB REPLACEMENT 2 A visual inspection at the rear of the vehicle indicated that
the right rear taillight bulb did not light. Removing a few screws from the plastic cover revealed the
taillight assembly.
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
TAILLIGHT BULB REPLACEMENT 3 The bulb socket is removed from the taillight assembly by
gently twisting the base of the bulb counterclockwise.
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James Halderman
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TAILLIGHT BULB REPLACEMENT 4 The bulb is removed from the socket by gently grasping the
bulb and pulling the bulb straight out of the socket. Many bulbs required that you rotate the bulb
90° (1/4 turn) to release the retaining bulbs.
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James Halderman
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TAILLIGHT BULB REPLACEMENT 5 The new 7443 replacement bulb is being checked with an
ohmmeter to be sure that it is okay before it is installed in the vehicle.
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James Halderman
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TAILLIGHT BULB REPLACEMENT 6 The replacement bulb in inserted into the taillight socket
and the lights are turned on to verify proper operation before putting the components back together.
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James Halderman
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OPTICAL HEADLIGHT AIMING 1 Before checking the vehicle for headlight aim, be sure that all
the tires are at the correct inflation pressure, and that the suspension is in good working condition.
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James Halderman
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OPTICAL HEADLIGHT AIMING 2 The headlight aim equipment will have to be adjusted for the
slope of the floor in the service bay. Start the process by turning on the laser light generator on the
side of the aimer body.
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James Halderman
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56 LIGHTING AND SIGNALING CIRCUITS
OPTICAL HEADLIGHT AIMING 3 Place a yardstick or measuring tape vertically in front of the
center of the front wheel, noting the height of the laser beam.
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James Halderman
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OPTICAL HEADLIGHT AIMING 4 Move the yardstick to the center of the rear wheel and
measure the height of the laser beam at this point. The height at the front and rear wheels should
be the same.
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OPTICAL HEADLIGHT AIMING 5 If the laser beam height measurements are not the same, the
floor slope of the aiming equipment must be adjusted. Turn the floor slope knob until the
measurements are equal.
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OPTICAL HEADLIGHT AIMING 6 Place the aimer in front of the headlight to be checked, at a
distance of 10 to 14 inches (25 to 35 cm). Use the aiming pointer to adjust the height of the aimer
to the middle of the headlight.
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OPTICAL HEADLIGHT AIMING 7 Align the aimer horizontally, using the pointer to place the
aimer at the center of the headlight.
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OPTICAL HEADLIGHT AIMING 8 Lateral alignment (aligning the body of the aimer with the
body of the vehicle) is done by looking through the upper visor. The line in the upper visor is aligned
with symmetrical points on the vehicle body.
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OPTICAL HEADLIGHT AIMING 9 Turn on the vehicle headlights, being sure to select the 9
correct beam position for the headlight to be aimed.
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OPTICAL HEADLIGHT AIMING 10 View the light beam through the aimer window. The position
of the light pattern will be different for high and low beams.
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OPTICAL HEADLIGHT AIMING 11 If the first headlight is aimed adequately, move the aimer to
the headlight on the opposite side of the vehicle. Follow the previous steps to position the aimer
accurately.
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OPTICAL HEADLIGHT AIMING 12 If adjustment is required, move the headlight adjusting
screws using a special tool or a 1/4-in. drive ratchet/socket combination. Watch the light beam
through the aimer window to verify the adjustment.
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