Ch13 Electrical Test Equipment

Graphing meters allow

Technicians to assess component serviceability by analyzing the waveforms.

4. An ohmmeter display indicates the resistance of a circuit is 3.2 k ohms. How many ohms of resistance does this equal? A. 3,200 ohms B. 32,000 ohms C. 320,000 ohms D. 3,200,000 ohms

4. 3,200 ohms, p304

The most basic diagnostic scanner is

A code reader. Code readers can access, interpret, and display on-board diagnostic (OBD) codes from the vehicle's ECM.

Which of the following is the most basic diagnostic scanner? A. Code reader B. Bidirectional control C. OBD D. Data link

A. Code reader

3. Which of the following multimeter arrangements is best used to check for an open circuit inside an ~3' long ground cable connecting the frame to the engine block? A. Disconnect the cable and check its continuity. B. Measure the available voltage at each end of the connected cable with the key on. C. Measure the amperage passing through the cable with the key off. D. With the key on, measure the cable resistance.

A. Disconnect the cable and check its continuity. , p303. Continuity determines whether two points are electrically connected. Continuity is also valuable when checking for opens and shorts.

DC inductive amp clamps typically use ___. A. Hall effect technology B. Current transformers C. Separate magnetic fields D. Source voltage

A. Hall effect technology

Never connect a DMM-multimeter set on the ___ function into a powered circuit because it will blow the fuse or battery in the meter or otherwise damage the meter. A. Ohmmeter B. Voltmeter C. Ammeter D. Test light

A. Ohmmeter

All of the following devices can be used together to identify the root cause of vehicle vibration, EXCEPT: A. Oscilloscope B. Road speed sensor C. Three-axis accelerometer D. Signal-conditioning module

A. Oscilloscope

2. Technician A says a popular type of LED test light is battery powered and has two LEDs - one read, the other green. Technician B says the LED light changes brightness depending on the circuit's voltage. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

A. P301-2 With two LEDs, the tech can find out what polarity or electrical charge is present in a circuit as its being tested. For example, once powered up, the probe first contacts test points in an energized circuit. If the probe is connected to a positive polarity current source, the red LED comes on. Touching a point int he circuit that is connected to battery negative or ground produces a green LED light. One disadvantage of LED lights is they provide no indication of the level of circuit voltage and become relatively bright when voltage is between 1.5 to 3.0 volts. An incandescent light changes brightness, depending on the circuit's voltage.

5. Technician A says before using a digital multimeter, the first task is to check that it's shunts and fuses are in place no functioning. Technician B says shunts do not operate like fuses and do not have a maximum rating. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

A. P304

4. Technician A says a multimeter measure resistance, continuity, voltage, and amperage. Technician B says the multimeter can be used to measure circuit resistance in amps to determine whether amperage is within specifications. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

A. P304; the amount of voltage that flows through the component or circuit depends on the circuit's resistance. If the return voltage is high, the circuit resistance is low, and if the return voltage is low, the circuit resistance is high.

8. Technician A says multimeters use a thermocouple accessory to measure temperature by contact. Technician B says heating the thermocouple produces amperage proportional to temperature. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

A. P311, 303. Accessories are connected to the standardized multimeter port location and size for positive voltage and common. The devices produce a voltage signal proportional to the state of the condition measured and display it on the multimeter.

Tech A says before using a digital multimeter, one of the 1st things to check is whether its shunts or fuses are in place and functioning. Tech B says shunts do not operate like fuses and do not have a max rating. Who is correct? A. Tech A B. Tech B C. Both Tech A and Tech B D. Neither Tech A nor Tech B

A. Tech A

Multimeters can be analog, digital, or high-impedance, and be

Auto-ranging or manual ranging types.

9. Which electrical service tool is best used to locate a broken-wire behind a body panel? A. A voltmeter B. A signal tracer C. A graphing mete D. An inductive-type clamp

B. A signal tracer, p312

A scan tool function which can control selected vehicle components or initiate systems actuator or diagnostic tests on command is called ___. A. Meter B. Bidirectional control C. Graphical display D. Scope

B. Bidirectional control

What does a circuit tracer inject into the wire to help determine the start and end location of a conductor? A. Heat intensity B. Radio signal C. Pressure waves D. Magnetic field

B. Radio signal

Technician A says back-probing or piercing wires is the best way to connect test wires for diagnosing problems with the system. Technician B says the life expectancy of an electric motor is an example of a component that can be evaluated by examining the small changes in current and voltage spikes caused by worn brushes. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

B. Tech B

Technician A says data link adapters are used to translate flash codes from the DLC into a format readable by a desktop or laptop computer. Technician B says the adapter may connect to the PC using a cable connected to a serial port, USB port, or wirelessly over the Internet or Bluetooth communication. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

B. Tech B

Technician A says code readers can guide a technician through certain procedures or have a built-in library of all the SAE generic trouble codes. Technician B says code readers can perform off-board or on-board reprogramming of a vehicle's computer modules, specifically the powertrain (ECM). Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

B. Tech B and C. Both was wrong. Guessing A. Tech A

7. How is the strength of a magnetic field sensed when measuring DC amperage? A. Measuring the number of lines of force in a rotating magnetic field. B. Using a Hall Effect sensor C. Using an inductor. D. Using a K-type thermocouple.

B. Using a Hall effect sensor, p311

1. Under which of the following conditions will the test light lamp illuminate when the lead wire is clipped and connected to a good chassis ground? A. When the test light probe is touching the battery negative post. B. When the test light probe is touching the grounded metal case of a starter motor. C. When the sets light probe is touching the circuit, but not the battery-ignition, side of a blown fuse. D. When the test light probe is touching the batter-ignition supply side of a blown fuse.

B. When the test light probe is touching the grounded metal case of a starter motor. , p?? This is NOT Correct. It is NOT B. I believe it to be C. Check.

Circuit tracers are useful for identifying circuit problems in wires

Deeply buried behind walls or in tightly bundled harnesses.

8. Which of the following test instruments is the best to measure electrical signals from multiple wires connecting to an ECU? A. An ammeter B. A voltmeter C. A signal tracer D. A break-out box

C. A signal tracer, p312

What is connected in series with a major component or wiring harness to an ECM? A. Circuit tracer B. Oscilloscope C. Break-out box D. Vibration analyzer

C. Break out box

1. Technician A says a test light is the simplest piece of electrical test equipment used to determine the presence or absence of current. Technician B says a test light consists of either an 18- or 36-volt incandescent light bulb connected to an insulated lead and a sharpened metal probe. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

C. P300

3. Technician A says multimeters are electrical measuring instruments combining functions of at least voltage, resistance, and amperage measurement into a single compact instrument. Technician B says digital multimeters are the most common category of multimeters and provide numerical displays of electrical data. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

C. P302

7. Technician A says ammeters measure the quantity of electrons flowing through a circuit per second of time. Technician B says measuring amperage requires that the circuit be broken, and the meter placed in series with the circuit, so that all the current flows through the meter shunts. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

C. P309

9. Technician A says circuit tracers, are electronic service tools used to trac a single wire over a distance to check for shorts, o open circuits. Technician B says circuit tracers can identify broken wires deeply buried behind walls or in tightly bundled harnesses. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

C. P312

10. Which is the best reason for using a vehicle communication interface adapter? A. To obtain engine-related fault code B. To enable a PC or laptop to communicate with a vehicle network. C. To enable bidirectional communication between a PC and a ABS module. D. To actuate network-connected output devices on the vehicle.

C. P313, 315

10. Technician A says vibration analyzers are used to identify the root cause of vehicle vibration. Technician B says typically, flywheel speed and road speed sensors are used along with data collected from a three-axis accelerometer placed under the driver's seat using a magnet. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

C. P313-14

5. An auto-ranging meter is set to measure resistance and the positive test lead is placed in the meters only amp probe port. There is infinite resistance displayed by the meter. What does it indicate? A. The meter is functioning correctly. B. There is current at the amp probe port. C. The meter shunt is open. D. The meter shunt is intact.

C. The meter shunt is open, p305

2. A test light illuminates when connected between a chassis ground and the grounded metal case of a blow motor that is switched on. Which of the following best describes the circuit's condition? A. The motor has a parasitic draw. B. The motor has a short to ground. C. The motor has an open ground short. D. The motor has a defective switch

C. The motor has an open ground short, p300. C is NOT Correct. D is NOT Correct. I believe it is A.

Which of the following test instruments is the best to measure electrical signals from multiple wires connecting to an ECU? A. An ammeter B. A voltmeter C. A signal tracer D. A break-out box

D. A break-out box

Which of the following test instruments is the best to measure electrical signals from multiple wires connecting to the ECU? A. An ammeter B. A. Voltmeter C. A signal tracer D. A break-out box

D. A break-out box

What can help to identify specific pin functions or circuit numbers during tests using break-out boxes? A. Graphing meters B. Display rulers C. Oscilloscopes D. OEM templates

D. OEM templates

What type of meter is not to be used with semiconductors and is potentially inaccurate when testing diodes? A. Ammeter B. Voltmeter C. Auto-ranging meter D. Ohmmeter

D. Ohmmeter

6. Technician A says the multimeter is connected in series with the circuit or component to measure the voltage dropped by the circuit resistance. Technician B says the ohmmeter works well in testing semiconductors. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

D. P306, 308

In the vibration analysis process, what is the specific role of the signal-conditioning module? A. To collect data on vibration B. To find the cause of vibration C. To analyze the vibration data collected D. To store the vibration data collected

D. To store the vibration data collected

Practices to observe when measuring amperage include:

Ensuring the circuit is powered. Ensuring the ammeter is connected in series, causing all the current in the circuit to flow through the meter shunts Observe polarity when measuring DC volts but not AC voltage Choosing the correct shunt or port in the meter for connecting leads based on anticipated amperage.

Technician A says a multimeter is connected in series with the circuit or component to measure the voltage dropped by the circuit resistance. Technician B says the ohmmeter works well in testing semiconductors. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

It is NOT A. Voltage meters are always connected across the device or in parallel. It is D. P305, Because ohmmeters are self-powered, it is critically important to remember that ohmmeters should never be connected to a powered circuit. Connecting an ohmmeter into a powered circuit blows the fuse or battery in the meter or otherwise damages the meter. Semiconductor circuits and some sensor should not be checked with an ohmmeter because the meter current may damage the device. Ohmmeters are ineffective when checking for resistances in high-amperage, very low-resistance circuits, such as when measuring battery cable voltage loss. Measuring voltage drop with a voltmeter when a circuit is operating is a more effective way of measuring resistances. P306, Fig 13-24 Ohmmeters use a small amount of current supplied by a battery to measure resistance. Voltage through the circuit is measured by the meter, which is reported in ohms. voltage is proportional to circuit resistance.

Technician A says ammeters measure the quantity of electrons flowing through a circuit per second of time. Technician B says measuring amperage requires the circuit be broken, and the meter placed in series with the circuit, so that all of the current flows through the meter shunts. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

It is NOT B. I am guessing C. Both. P309. C is NOT Correct. It is A. Ammeters measure the quantity of electrons flowing through a circuit per second of time. Amperage is the volume aspect of current flow, and voltage is the speed or pressure of electrical flow. Measuring amperage requires that the circuit be broken, the meter placed in series with the circuit, so that all the current flows through the meter shunts.

Under which of the following conditions will the test light lamp illuminate when the lead wire is clipped and connected to a good chassis ground? A. When the test light probe is touching the battery negative post B. When the test light probe is touching the grounded metal case of a starting motor C. When the test light probe is touching the circuit, but not the battery-ignition side of a blown fuse D. When the test light probe is touching the battery-ignition supply side of a blown fuse

It is NOT B. It must be C. To check for an opening in a circuit, the vehicle battery is first disconnected. The light's alligator clip is connected to ground and the circuit is probed sequentially from the switch or power supply to the load. where the test light glow, the circuit is closed from chassis ground to power. An open circuit prevents current from traveling from the ground to an insulated positive. For example, a broken wire between a heater blower motor and fuse illuminates between the blower motor and beak in the wire, but not after the break and before the fuse. Grounded circuits are checked in a similar manner. While probing the circuit, its switches and connectors are opened. The light stays illuminated in the section that is grounded. However, the light goes out after the section of circuit with an un-intentional ground is disconnected. Self-powered voltmeters with probes are also useful for close-quarter probing of electrical circuits.

Technician A says a test light is the simplest piece of electrical test equipment used to determine the presence or absence of current. Technician B says a test light consists of either an 18- or 36-volt incandescent light bulb connected to an insulated lead and a sharpened metal probe. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

It is NOT C. Both. It must be A. Tech A. The book says a 12- or 24-volt incandescent light bulb.

What is the correct procedure to measure amperage in a DC circuit? A. Open the circuit and place the meter in series with an energized circuit. B. Connect the ammeter in parallel and observe polarity. C. Disconnect the battery and connect the meter in parallel. D. Open the circuit and connect the meter series with a current-limiting resistor.

It is NOT D. I believe A. It is in series when testing for amperage.

An auto-ranging meter is set to measure resistance and the positive test lead is placed int he meters only amp probe port. There is infinite resistance displayed by the meter. What does it indicate? A. The meter is functioning correctly B. There is current at the amp probe port. C. The meter shunt is open. D. The meter shunt is intact.

It is NOT D. It is NOT C. I believe A.

A test light illuminates when connected between a chassis ground and the grounded metal case of a blower motor that is switched on. Which of the following best describes the circuit's condition? A. The motor has a parasitic draw. B. The motor has a short to ground. C. The motor has an open ground circuit. D. The motor has a defective switch.

It is NOT D. Therefore, I am guessing A.

Technician A says multimeters use a thermocouple accessory to measure temperature by contact. Technician B says heating the thermocouple produces amperage proportional to temperature. Who is correct? A. Technician A B. Technician B C. Both Technician A and Technician B D. Neither Technician A nor Technician B

It is not C. Both. B. Tech B is NOT correct. Choose A.

6. What is the correct procedure to measure amperage in a DC circuit? A. Open the circuit and place the meter in series with an energized circuit. B. Connect the ammeter in parallel and observe polarity C. Disconnect the battery and connect the meter in parallel. D. Open the circuit and on next the meter series with a current-limiting resistor.

It is not D. I say A.

When performing electrical circuit diagnostics, purpose-made

Jumper wires, fused jumper wires, and break-out boxes are helpful for quickly and effectively diagnosing problems without damaging wiring or connectors by back-robing or piercing wires.

Inductive amp clamps are useful tools for

Measuring amperage without opening the circuit.

Measuring amperage requires the

Powered circuit is opened, and the meter placed in series with the circuit, so that all the current flows through the meter shunts.

A variety of scanner types are used to

Read serial data from a vehicle data link interface.

By checking the resistance or circuit continuity with an ohmmeter, a circuit can be evaluated for

Shorts, opens or high resistance.

Self-powered test lights are like regular test lights except

That they contain a 1.5-volt battery.

When using an ohmmeter

The circuit must never be powered. The meter is connected in parallel across the circuit or component to measure the voltage dropped by the circuit resistance. It is not necessary to observe polarity when connecting test leads. The positive test lead is connected to the ohms port and the negative lead to the common port of the meter. the meter needs to be properly ranged if not using an auto-ranging meter. Start at the highest range values and work down if the resistance is unknown.

Voltmeters measure

The difference in electrical pressure or electron velocity between two different points in the circuit.

The simplest piece of electrical test equipment used

To determine the presence or absence of current is a test light

A variety of electrical test instruments are needed

To diagnose and repair electrical problems.

Multimeters use a thermocouple accessory to measure temperature by contact. Heating the thermocouple produces

Voltage proportional to temperature.

Multimeters are electrical measuring instruments combining functions like

Voltage, resistance, and amperage measurement into a single compact instrument.

Ohmmeters are ineffective when checking for resistances in high-amperage, low-resistance circuits, such as

When measuring battery cable voltage loss.

Before using a digital meter, one of the first things to check is

Whether its shunts or fuses are in place and functioning. Shunts are internal conductors with a small calibrated resistance, which directs some current flow into the meter when when measuring amperage.