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OBJECTIVES
After studying Chapter 8, the reader should be able to:
1. Prepare for ASE Electrical/Electronic Systems (A6)
certification test content area “A” (General
Electrical/Electronic System Diagnosis).
2. Explain how to set a digital meter to read voltage,
resistance, and current.
3. Explain meter terms and ratings.
4. Interpret meter readings and compare to factory
specifications.
5. Discuss how to properly and safely use meters.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TEST LIGHTS
• A test light is simply a light
bulb with a probe and a
ground wire attached.
FIGURE 8-1 A 12-volt test light is
attached to a good ground while
probing for power.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TEST LIGHTS
FIGURE 8-2 A test light can be used to locate an
open in a circuit. Note that the test light is grounded
at a different location than the circuit itself.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TEST LIGHTS
Continuity Test Lights
• A continuity light illuminates
whenever it is connected to
both ends of a wire that has
continuity or is not broken.
FIGURE 8-3 Self-powered test lights contain a battery, clamp,
and probe. This type of test light should not be used on any
computer-controlled circuits because the applied voltage can
damage delicate electronic components or circuits.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TEST LIGHTS
LED Test Lights
• An LED test light uses an
LED instead of a standard
automotive bulb for a visual
indication of voltage.
FIGURE 8-4 High-impedance test light. An LED test light can be easily made using lowcost components and an old ink pen. With the 470 ohm resistor in series with the LED,
this tester only draws 0.025 ampere (25 milliamperes) from the circuit being tested. This
low current draw helps assure the technician that the circuit or component being tested
will not be damaged by excessive current flow.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
TEST LIGHTS
Logic Probe
• A logic probe is an
electronic device that lights
up a red (usually) LED if
the probe is touched to
battery voltage.
FIGURE 8-5 A logic probe connected to the vehicle
battery and relay used to check for power, ground, or
a pulse.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
• Digital multimeter (DMM) and digital voltohmmilliammeter (DVOM) are terms commonly
used for electronic high-impedance test meters.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
FIGURE 8-6 Typical digital
multimeter. The black meter lead
always is placed in the COM
terminal. Except when measuring
the current in amperes, the red
meter test lead remains in the V
terminal.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
FIGURE 8-7 Common abbreviations used on the display face of many
digital multimeters. (Courtesy of Fluke Corporation)
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
FIGURE 8-8 A summary chart indicating what measurement type may be used to test which
vehicle system. (Courtesy of Fluke Corporation)
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
Measuring Voltage
• A voltmeter measures the pressure or potential of
electricity in units of volts.
• A voltmeter is connected to a circuit in parallel.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
Measuring Voltage
FIGURE 8-9 A typical autoranging digital multimeter automatically selects the proper scale to read the
voltage being tested. The scale selected is usually displayed on the meter face. (a) Note that the
display indicates “4,” meaning that this range can read up to 4 volts. (b) The range is now set to the
40 volt scale, meaning that the meter can read up to 40 volts on the scale. Any reading above this
level will cause the meter to reset to a higher scale. If not set on autoranging, the meter display would
indicate OL if a reading exceeds the limit of the scale selected. (Courtesy of Fluke Corporation)
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
Measuring Voltage
FIGURE 8-10 Typical digital multimeter (DMM) set to read DC volts.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
Measuring Resistance
• An ohmmeter measures the resistance in ohms of a
component or circuit section when no current is
flowing through the circuit.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
Measuring Resistance
FIGURE 8-11 Using a digital multimeter set
to read ohms () to test this light bulb. The
meter reads the resistance of the filament.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
FIGURE 8-12 Typical digital multimeter
showing OL (over limit) on the readout with
the ohms () unit selected. This usually means
that the unit being measured is open (infinity
resistance) and has no continuity.
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
Measuring Resistance
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
Measuring Resistance
FIGURE 8-13 Many digital multimeters can have the display indicate zero to compensate for test lead
resistance.(1) Connect leads in the Vand COM meter terminals.(2) Select the scale.(3) Touch the two meter
leads together.(4) Push the “zero” or “relative” button on the meter.(5) The meter display will now indicate zero
ohms of resistance. (Courtesy of Fluke Corporation)
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
Measuring Amperes
• An ammeter measures the flow of current through a
complete circuit in units of amperes.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
Measuring Amperes
FIGURE 8-14 In this digital multimeter set to read DC amperes, note that the red lead is
placed in the far left-hand socket of the meter. The meter is displaying the current flow
(4.18A) through the electric fuel pump on this General Motors 3800 V6 engine.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL MULTIMETERS
Measuring Amperes
FIGURE 8-15 An inductive ammeter clamp is used with all starting and
charging testers to measure the current flow through the battery cables.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
AC/DC CLAMP-ON DIGITAL MULTIMETER
• An AC/DC clamp-on digital multimeter (DMM) is
a useful meter for automotive diagnostic work and
uses a Halleffect sensor to measure current.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
AC/DC CLAMP-ON DIGITAL MULTIMETER
FIGURE 8-16 A typical mini clamp-on-type digital
multimeter. This meter is capable of measuring
alternating current (AC) and direct current (DC) without
requiring that the circuit be disconnected to install the
meter in series. The jaws are simply placed over the
wire and current flow through the circuit is displayed.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
FIGURE 8-17 An AC and DC current clamp
such as the one shown can be used with a
regular digital multimeter. The amp probe
contains a separate battery and electronic
circuit that converts the amperage reading
into a millivolt (mV) signal.
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
FUSE YOUR METER LEADS!
FIGURE 8-18 Note the blade-type fuse holder soldered in series with one
of the meter leads. A 10 amp fuse helps protect the internal meter fuse (if
equipped) and the meter itself from damage that might result from excessive
current flow if accidentally used incorrectly.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ELECTRICAL UNIT PREFIXES
• Electrical units are measured in numbers such as 12 volts,
150 amperes, and 470 ohms.
• Kilo (k) means 1,000.
• If the value is over 1 million (1,000,000), then the prefix
mega (M) is often used.
• Small units of measure expressed in 1/1,000 are prefixed by
milli (m).
• The micro unit is represented by the Greek letter mu (μ).
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
“OL” DOES NOT MEAN THE METER IS READING “NOTHING”
FIGURE 8-19 A summary of the test meter hookup.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW TO READ DIGITAL METERS
• Getting to know and use a digital meter takes time
and practice.
– Select the proper unit of electricity for what is being
measured.
– Place the meter leads into the proper input terminals.
– Measure the component being tested.
– Interpret the reading.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW TO READ DIGITAL METERS
FIGURE 8-20 Always look at the meter display when a measurement is being made,
especially if using an autoranging meter. (Courtesy of Fluke Corporation)
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW TO READ DIGITAL METERS
RMS versus Average
• Alternating current voltage waveforms can be true
sinusoidal or nonsinusoidal.
– A true sine wave pattern measurement will be the same
for both root-mean-square (RMS) and average reading
meters.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW TO READ DIGITAL METERS
RMS versus Average
FIGURE 8-21 When reading AC voltage signals, a true RMS meter (such as a Fluke 87)
provides a different reading than an average responding meter (such as Fluke 88).The only
place this difference is important is when a reading is to be compared with a specification.
(Courtesy of Fluke Corporation)
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW TO READ DIGITAL METERS
Resolution, Digits, and Counts
• Meter resolution refers to how small or fine a
measurement the meter can make.
• The terms digits and counts are used to describe a
meter’s resolution.
– DMMs are grouped by the number of counts or digits they
display.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW TO READ DIGITAL METERS
Resolution, Digits, and Counts
FIGURE 8-22 This meter display shows 052.2 AC volts. Notice that the zero beside the 5
indicates that the meter can read over 100 volts AC with a resolution of 0.1 volt.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW TO READ DIGITAL METERS
Accuracy
• Meter accuracy is the largest allowable error that
will occur under specific operating conditions.
• Accuracy for a DMM is usually expressed as a
percent of reading.
– An accuracy of 1% of reading means that for a displayed
reading of 100.0 V, the actual value of the voltage could
be anywhere between 99.0 V to 101.0 V.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
HOW TO READ DIGITAL METERS
Accuracy
• Unacceptable 1.00%
• Okay 0.50% (1/2%)
• Good 0.25% (1/4%)
• Excellent 0.10% (1/10%)
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
METER USAGE ON HYBRID ELECTRIC VEHICLES
• Many hybrid electric vehicles use system voltage as
high as 650 volts DC.
• These categories are ratings for overvoltage
protection and are rated CAT I, CAT II, CAT III, and
CAT IV.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
METER USAGE ON HYBRID ELECTRIC VEHICLES
FIGURE 8-23 Be sure to only use a
meter that is CAT III rated when
taking electrical voltage measurements
on a hybrid vehicle.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
FIGURE 8-24 Always use meter leads that
are CAT III rated on a meter that is also
CAT III rated to maintain the protection
needed when working on hybrid vehicles.
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
ALWAYS USE FUSED JUMPER LEADS
FIGURE 8-25 A typical fused jumper lead. Fused jumper (test) leads can
be purchased or can be made by a technician.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 1
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
DIGITAL METER USAGE 2
cont
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
SUMMARY
1.
2.
3.
4.
5.
6.
Digital multimeter (DMM) and digital volt-ohmmilliammeter
(DVOM) are terms commonly used for electronic highimpedance test meters.
Use of a high-impedance digital meter is required on any
computer-related circuit or component.
Ammeters measure current and must be connected in
series in the circuit.
Voltmeters measure voltage and are connected in parallel.
Ohmmeters measure resistance of a component and must
be connected in parallel, with the circuit or component
disconnected from power.
Logic probes can indicate the presence of ground, as well
as power.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
REVIEW QUESTIONS
1. Explain why most digital meters are called
high-impedance meters.
2. Describe how an ammeter should be
connected to an electrical circuit.
3. Explain why an ohmmeter must be
connected to a disconnected circuit or
component.
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
1. Inductive ammeters work because of what
principle?
a)
b)
c)
d)
Magic
Electrostatic electricity
A magnetic field surrounds any wire carrying a current
Voltage drop as it flows through a conductor
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
1. Inductive ammeters work because of what
principle?
a)
b)
c)
d)
Magic
Electrostatic electricity
A magnetic field surrounds any wire carrying a current
Voltage drop as it flows through a conductor
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
2. A meter used to measure amperes is called a(n)
_____.
a)
b)
c)
d)
Amp meter
Ampmeter
Ammeter
Coulomb meter
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
2. A meter used to measure amperes is called a(n)
_____.
a)
b)
c)
d)
Amp meter
Ampmeter
Ammeter
Coulomb meter
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
3. A voltmeter should be connected to the circuit
being tested _____.
a)
b)
c)
d)
In series
In parallel
Only when no power is flowing
Both a and c
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
3. A voltmeter should be connected to the circuit
being tested _____.
a)
b)
c)
d)
In series
In parallel
Only when no power is flowing
Both a and c
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
4. An ohmmeter should be connected to the circuit
being tested _____.
a)
b)
c)
d)
In series
In parallel
Only when no power is flowing
Both b and c
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
4. An ohmmeter should be connected to the circuit
being tested _____.
a)
b)
c)
d)
In series
In parallel
Only when no power is flowing
Both b and c
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
5. A high-impedance meter _____.
a)
b)
c)
d)
Measures a high amount of current flow
Measures a high amount of resistance
Can measure a high voltage
Has a high internal resistance
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
5. A high-impedance meter _____.
a)
b)
c)
d)
Measures a high amount of current flow
Measures a high amount of resistance
Can measure a high voltage
Has a high internal resistance
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
6. A meter is set to read DC volts on the 4 volt scale.
The meter leads are connected at a 12 volt
battery. The display will read _____.
a)
b)
c)
d)
0.00
OL
12 V
0.012 V
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
6. A meter is set to read DC volts on the 4 volt scale.
The meter leads are connected at a 12 volt
battery. The display will read _____.
a)
b)
c)
d)
0.00
OL
12 V
0.012 V
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
7. What could happen if the meter leads were
connected to the positive and negative terminals
of the battery while the meter and leads were set
to read amperes?
a)
b)
c)
d)
Could blow an internal fuse or damage the meter
Would read volts instead of amperes
Would display OL
Would display 0.00
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
7. What could happen if the meter leads were
connected to the positive and negative terminals
of the battery while the meter and leads were set
to read amperes?
a)
b)
c)
d)
Could blow an internal fuse or damage the meter
Would read volts instead of amperes
Would display OL
Would display 0.00
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
8. The highest amount of resistance that can be read
by the meter set to the 2 k scale is _____.
a)
b)
c)
d)
2,000 ohms
200 ohms
200 k (200,000 ohms)
20,000,000 ohms
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
8. The highest amount of resistance that can be read
by the meter set to the 2 k scale is _____.
a)
b)
c)
d)
2,000 ohms
200 ohms
200 k (200,000 ohms)
20,000,000 ohms
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
9. If a digital meter face shows 0.93 when set to read
k, the reading means _____.
a)
b)
c)
d)
93 ohms
930 ohms
9,300 ohms
93,000 ohms
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
9. If a digital meter face shows 0.93 when set to read
k, the reading means _____.
a)
b)
c)
d)
93 ohms
930 ohms
9,300 ohms
93,000 ohms
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
10. A reading of 432 shows on the face of the meter
set to the millivolt scale. The reading means
_____.
a)
b)
c)
d)
0.432 volt
4.32 volts
43.2 volts
4,320 volts
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
CHAPTER QUIZ
10. A reading of 432 shows on the face of the meter
set to the millivolt scale. The reading means
_____.
a)
b)
c)
d)
0.432 volt
4.32 volts
43.2 volts
4,320 volts
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
END
Diagnosis and Troubleshooting of Automotive Electrical,
Electronic, and Computer Systems, Fifth Edition
By James D. Halderman
© 2010 Pearson Higher Education, Inc.
Pearson Prentice Hall - Upper Saddle River, NJ 07458
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