aut-271
When testing an ECT sensor with a scan tool, what should be the maximum difference between the coolant temperature readings on the scan tool and the red pyrometer?
5°C
A high-speed CAN BUS communicates with a scan tool through which terminal(s)?
6 and 14
What is the ideal tension range for a V-belt with top width of 5/16 in?
60-85 lb
Which of the following is possible causes of solenoid clicks?
Coolant on top of the pistons, causing a hydrostatic lock
Which sensor (if the vehicle is equipped with one) does the PCM use in addition to the engine coolant temperature (ECT) sensor to determine engine temperature?
Cylinder head temperature (CHT)
A digital meter that can show waveforms is called a __________.
GMM
Which of the following is true of a spice pack?
It is the central point of star link.
Which bulletin of the Society of Automotive Engineers (SAE) standardizes the name of the automotive computer as the powertrain control module (PCM)?
J1930
Which sensor does the TP sensor backup if the PCM determines that a failure has occurred?
MAF sensor
What is engine mapping?
Manually setting engine factors to optimize output settings
What is the second step of the disassembly procedure of a starter?
Mark the location of the through bolts on the field housing to help align them during reassembly.
Which among the following is a high-authority sensor?
Mass airflow (MAF) sensor
A transistor is controlled by the polarity and current at the _________________.
base
Bench testing of a starter should be done ______________.
before installing a new starter
Measuring the current flow required by a horn requires that the ammeter be connected to the circuit _________ and the horn button be depressed by an assistant.
in series
A module is also known as a ___________.
node
To check for ripple voltage from the alternator, connect a digital multimeter (DMM) and select ____________.
AC volts
__________ displays rapidly and cannot be set to show or freeze a display.
An analog scope
Analog signals from sensors are changed to digital signals for processing by the computer through which type of circuit?
Analog-to-digital convertor
Which defect in MAF sensors is applicable for the P0100, P0101, P0102, and P0103 DTCs?
Defective MAF sensor
If the transmission fluid temperature (TFT) sensor indicates cold automatic transmission fluid temperature, what would the PCM do to the shifts?
Delayed shift points and torque converter clutch disabled
What are the two main uses of the airflow sensors for the PCM?
Determine the required fuel amount and serve as the backup for the throttle position (TP) sensor.
The twisted pair is used in what type of communication?
Differential
Which among the following tools is used to test a TP sensor?
Digital voltmeter
What does excessive AC voltage indicate?
Fault with the rectifier diodes or stator windings inside the alternator
A _________ can be used to locate an open in a circuit when it is grounded at a different location than the circuit itself.
test light
A P0122 DTC is retrieved using a scan tool. This DTC means __________________.
the TP sensor could be shorted-to-ground
A battery should be checked for ________.
the battery case being clean
In a tap test, the MAF sensor is defective if ___________________.
the engine stumbles or stops when the MAF sensor is gently tapped
When jump starting, ________.
the last connection should be the engine block of the dead vehicle
If the clearance between the starter pinion and the engine flywheel is too great, ______________.
the starter produces a high-pitched whine during cranking
Inductive ammeter measures ________ surrounding the wire carrying the current and uses a Hall effect sensor to measure current.
the strength of the magnetic field
Pulse trains differ from an AC signal in that _____________.
they do not go below zero
Some vehicles use the _________ sensor instead of the intake air temperature (IAT) sensor.
throttle-body temperature (TBT)
Setting the _______ means setting how much time is displayed in each block, called a division.
time base
In Karman vortex sensors, the air mass is calculated by measuring the ____________.
time required by sound waves to travel across the turbulent air passage
Breakout box(BOB) is used:
to gain access to the terminals.
A semiconductor is a material ________.
with exactly four electrons in the outer orbit of its atoms
When testing an alternator minimum required output, what is an acceptable reading?
Five amperes greater than the accessory load
What is the first step of voltage drop testing?
Disable the ignition or fuel injection by disconnecting the primary (low-voltage) electrical connection(s) from the ignition module or ignition coils.
What is the first step for removing a starter?
Disconnect the battery negative cable.
Which of the following is true about nodes?
Driver's side window module causes the window to go down.
Which of the following is true about open circuit voltage and dynamic voltage?
Dynamic voltage is the voltage with the circuit in operation.
The sensor that most determines fuel delivery when a fuel-injected engine is first started is the ________.
ECT sensor
All OBD-II vehicles use what type of read-only memory?
EEPROM
Which of the following is true about electrostatic discharge?
Electrostatic discharge (ESD) is created when static charges build up on the human body when movement occurs.
Where is the ECT sensor located?
Engine coolant passage
Which parameters / data are used in the speed density method to calculate the required fuel?
Engine speed and MAP sensor data
Which item is a computer output device?
Evaporative emission control solenoid
Which of the following would NOT be used to check drive belt wear?
Groove color change
It is the central point of star link.
Help reduce interference into other systems in the vehicle
GMLAN is the General Motors term for which type of module communication?
High-speed CAN
Which type of sensor uses a burn-off circuit?
Hot wire MAF sensor
Which of the following is a possible cause for P0113 DTC?
IAT sensor electrically and internally open
Which of the following test determines if any circuit in a vehicle is causing a drain?
Ignition off draw (IOD) test
What happens to the voltage measured at the ECT sensor when the thermostat opens?
Increases slightly
_____________ is the process that refines the input signal so that it can be handled by the computer circuits.
Input conditioning
What is the last step of removing a starter?
Inspect the flywheel (flexplate) for ring gear damage. Also check that the mounting holes are clean and the mounting flange is clean and smooth. Service as needed.
Which of the following monitors the battery operation?
Intelligent battery systems
Which of these is one of the features of CAN protocol?
It is cost-effective
Which of the following is true of a defective module?
It is not capable of sending any trouble message.
Which one of these steps should be followed to prevent damage to components?
Keep the replacement electronic component in the protective wrapping.
What are the possible causes for the starter clicking when engaged?
Low battery voltage; loose or corroded battery connections
Frequency measurements are used while checking which of the following?
Mass airflow (MAF) sensors for proper operation
A technician attaches one lead of a digital voltmeter to the ground terminal of the TP sensor and the other meter lead to the negative terminal of the battery. The ignition is switched to on, engine off and the meter displays 37.3 mV. Technician A says that this is the signal voltage and is a little low. Technician B says that the TP sensor ground circuit has excessive resistance. Which technician is correct?
Neither Technician A nor B
Two technicians are discussing Karman Vortex sensors. Technician A says that they contain a burn-off circuit to keep them clean. Technician B says that they contain a movable vane. Which technician is correct?
Neither Technician A nor B
When testing the ECT sensor with the connector disconnected, the technician should select what position on the DMM?
Ohms
What is a core?
Old alternator
Which common action is initiated by the PCM when the transmission fluid temperature (TFT) sensor detects temperature of the automatic transmission fluid above 260°F and below 32°F?
Overdrive is disabled.
The SAE term for the vehicle computer is ____________.
PCM
After installing the starter, the technician should perform which of the following?
Perform a starter amperage draw test and check for proper engine cranking.
Which of the following is true of hole theory?
The unfilled holes move opposite to the flow of the electrons.
What is the major advantage of a clamp-on-type meter?
There is no need to break the circuit to measure current in amperes.
Most TP sensors have how many wires?
Three
Which sensor was used to measure throttle position before the introduction of electronic throttle control (ETC) systems?
Throttle position (TP) sensor
What is the purpose and function of an inverter?
To change DC voltage to AC voltage
What is the purpose for conducting the charging voltage test?
To check the charging system voltage at the battery
Which of the following is a function of UART?
To control message traffic on the data line
What is the importance of holes in the brushes?
To hold the brushes up in the holder
To avoid damage from an electrostatic discharge, the technician should do what before handling sensitive electronic components.
Touch a metal surface on the vehicle
____________ is the voltage that must be detected by the scope before the pattern is displayed.
Trigger level
What two things can a vehicle computer actually perform (output)?
Turn something on or turn something off
Which of the following is one of the method to maintain memory?
Use a commercially available memory saver to prevent possible damage.
Which of the following is one of the steps needed to register a battery?
Use a factory or factory level aftermarket scan tool to the DLC.
What unit of electricity is used as a signal for a computer?
Volt
________________________involves connecting a voltmeter set to read DC volts to the suspected high-resistance cable ends and cranking the engine.
Voltage drop testing of the wire
In which of the following conditions is the intake air temperature (IAT) sensor more helpful than the engine coolant temperature (ECT) sensor in understanding performance and driveability?
When a vehicle at normal operating temperature is switched off in cold weather and is switched on again
When should a technician conduct the sniff test?
When checking for the root cause of an alternator failure
Which of the following is true for stepped ECT circuits?
When the temperature is below 50°C, the ECT sensor voltage is applied through a high-value resistance.
Which one of the following is the safety procedure that is to be followed to prevent physical injury?
When working on any electrical component on a vehicle, disconnect the negative battery cable from the battery.
Many scan tools are capable of displaying the voltage levels captured by the scan tool through the ___________ on a screen.
data link connector
When the temperature of the coolant increases, the resistance of the engine coolant temperature (ECT) _______.
decreases
Duration of on-time in comparison to the total period of the cycle is called __________.
duty cycle
An actuator converts _______ energy into _______ action.
electrical, mechanical
Newer accessory drive belts are made from ________.
ethylene propylene diene monomer
Air that enters the engine without passing through the air flow sensor is called ____________.
false air
The MAF sensor is used mostly by the PCM to determine the amount of ________ to deliver to the engine.
fuel
The faults missed by the digital storage scope are called ________.
glitches
An oscilloscope display is called a ___________.
graticule
A high-impedance meter _________.
has a high internal resistance
Cycles per second are expressed in ___________.
hertz
The four basic computer functions include __________________.
input, processing, storage, and output
A(n) _________ is an electronic circuit that changes DC into AC.
inverter
The arrow in a symbol for a semiconductor device ________.
is attached to the emitter on a transistor
A TP sensor is said to be skewed when __________________.
its output is out of the usual 0-5 volt range
A digital scope uses _________.
liquid crystal display
In the hot wire and hot film sensor, greater flow of current indicates ________ air flow.
more
Cold incoming air requires a rich fuel-air mixture because it is denser and contains __________.
more oxygen
Temporary memory that retains data even after battery disconnection is called _________.
nonvolatile RAM
An ohmmeter should be connected to the circuit or component being tested ________.
only when no power is flowing (electrically open circuit)
A contaminated airflow sensor usually _______ the amount of air entering the engine at idle and ______ the amount of air entering the engine at higher engine speeds.
overestimates, underestimates
A zener diode is normally used for voltage regulation. A zener diode, however, can also be used for high-voltage spike protection, if connected ________.
positive to cathode, ground to anode
Voltage signals (waveforms) that do not go below zero are called _______________.
pulse trains
Because the computer controls the on-time of the solenoid, the solenoid and its circuit control are called _________.
pulse-width modulated
The PCM _____________ fuel-injector pulses if the throttle is lowered to the floor during engine cranking.
reduces or completely eliminates
Most vehicles that use a computer-controlled charging system can be diagnosed using a ________.
scan tool
When testing a diode with the multimeter set on "Diode Check," a reading of 0.6 volt is obtained. This indicates that the diode being tested is a __________.
silicon diode
When charging a maintenance free (lead calcium) battery, _______.
slow charging the battery 5 amperes is the maximum.
A fuel-injection system that does not use a sensor to measure the amount (or mass) of air entering the engine is usually called a(n) ________ type of system.
speed density
A voltmeter should be connected to the circuit being tested ________.
in parallel
Duty cycle is _______.
the amount of time, by percentage, that a signal is on compared to being off
When measuring the specific gravity of the electrolyte, the maximum allowable difference between the highest and lowest hydrometer readings is ________.
0.050
Although usual idle TP sensor voltage is 10% of the TP sensor voltage at wide-open throttle (WOT), it can vary between ________.
0.3 and 1.2 volts
A reading of 432 shows on the face of the meter set to the millivolt scale. The reading means ________.
0.432 volt
Typical TP sensor voltage at idle is about ________.
0.5 volt or 10% of WOT TP sensor voltage
An alternator diode is being tested using a digital multimeter set to the diode check position. A good diode will read _______ if the leads are connected one way across the diode and ______ if the leads are reversed.
0.551 / OL
The steps involved in the diagnosis of a fault in the cranking circuit are:
1. Verify the customer concern. 2. Visually inspect the battery and battery connections. 3. Test battery condition. 4. Check the control circuit. 5. Check voltage drop of the starter circuit.
A throttle position sensor waveform is going to be observed. At what setting should the volts per division be set to see the entire waveform from 0 to 5 volts?
1.0 V/division
The forward-bias voltage required for an LED is ________.
1.5 to 2.2 volts
Analog (needle-type) meters are almost always lower than _______ and should not be used to measure any computer or electronic circuit.
10 megohms
A good alternator should produce less than ________ of its rated amperage output in AC ripple amperes.
10%
A test light of how many volts is designed for household current?
110 or 220 volts
Terminal 16 of the OBD-II data link connector is used for which of the following?
12 V positive
The ideal battery voltage of battery with a state of charge of 75% is ______.
12.4
An acceptable charging circuit voltage on a 12-volt system is ________.
13.5 to 15.0 volts
Which terminal of the data link connector does General Motors use for Class 2 communication?
2
If an autoranging meter is manually set to the 2 kilohm scale, the highest that the meter reads is _______.
2,000 ohms
Normal battery drain (parasitic drain) in a vehicle with many computer and electronic circuits is _______.
20 to 30 milliamperes
The highest amount of resistance that can be read by the meter set to the 2-kΩ scale is ________.
2000 ohms
An LED test light requires only about ________ to light.
25 mA
The typical MAF reading on a scan tool with the engine at idle speed and normal operating temperature is _____.
3 to 7 grams per second
Normal throttle position voltage on most vehicles at the wide-open throttle (WOT) position is ______ volt(s).
4.5
The PCM supplies the Vref or 5-volt reference voltage to the TP sensor. What is the usual range of Vref?
4.8 to 5.1 volts
When checking the ECT sensor with a scan tool, about what temperature should be displayed if the connector is removed from the sensor with the key on, engine off?
40°F (40°C)
Which terminal of the OBD-II data link connector is the signal ground for all vehicles?
5
Setting the time base to 50 ms per division will allow the technician to view a waveform how long in duration?
500 ms
What is the temperature difference maintained between the air temperature and the wire in a hot wire sensor?
70°C
A typical IAT or ECT sensor reads about 3,000 ohms when tested using a DMM. This resistance represents a temperature of about ________.
70°F (20°C)
If a digital meter face shows 0.93 when set to read kΩ, the reading means ________.
930 ohms
When performing an alternator output test, which tool should the technician choose?
A load tester
Which of the following is true of the three-minute charge test?
A three-minute charge test is used to check if a battery is sulfated,
The "brain" of the computer is the ______________.
CPU
Oscilloscopes use what type of lead connector?
BNC
A MAF sensor on a General Motors 3800 V-6 is being tested for contamination. Technician A says that the sensor should show over 100 grams per second on a scan tool display when the accelerator is depressed to WOT on a running engine. Technician B says that the output frequency should exceed 7000 Hz when the accelerator pedal is depressed to WOT on a running engine. Which technician is correct?
Both Technicians A and B
A P0102 DTC is being discussed. Technician A says that a sensor circuit shorted-to-ground can be the cause. Technician B says that an open sensor voltage supply circuit could be the cause. Which technician is correct?
Both Technicians A and B
Technician A says that a discharged battery (lower than normal battery voltage) can cause solenoid clicking. Technician B says that a discharged battery or dirty (corroded) battery cables can cause solenoid clicking. Which technician is correct?
Both Technicians A and B
Technician A says that module communications networks are used to reduce the number of wires in a vehicle. Technician B says that a communications network is used to share data from sensors, which can be used by many different modules. Which technician is correct?
Both Technicians A and B
Two technicians are discussing what could be the cause of slow cranking and excessive current draw. Technician A says that an engine mechanical fault could be the cause. Technician B says that the starter motor could be binding or defective. Which technician is correct?
Both Technicians A and B
How can a test light be used to test a ground connection?
By connecting the tip of the test light to a good ground with the other end to the positive terminal of a battery
When testing a TP sensor, how is the throttle position changed?
By depressing the foot pedal
Which of the following statements is true?
CAN H goes to 3.5 volts when transmitting.
Which among the following statements is true?
Central processing unit (CPU) executes the mathematical and logical functions.
What precautions are needed when charging an AGM-type battery?
Charging voltage should be at or below 14.4 volts.
Which of these is one of the steps in finding faults?
Check everything that works and does not work
Which one of these would NOT be a diagnostic step when diagnosing a "no crank" customer concern?
Check the condition of the engine oil.
Some computers use more than one microprocessor. What is the second microprocessor called?
Coprocessor
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?
Could blow an internal fuse or damage the meter
Which among the following statements is true?
Cruise control, speedometer, and airbag systems use the vehicle speed (VS) sensor.
To check the charging voltage, connect a digital multimeter (DMM) to the positive (+) and the negative (-) terminals of the battery and select ________________.
DC volts
When testing an ECT sensor on a vehicle, a digital multimeter can be used and the signal wires back probed. What setting should the technician use to test the sensor?
DC volts
Which of these causes an electric component to fail?
Poor connection
What are the possible causes for a starter rotating slowly?
Possible high resistance in the battery cables or connections; possible defective or discharged battery; possible worn starter bushings, causing the starter armature to drag on the field coils; possible worn starter brushes or weak brush springs; possible defective (open or shorted) field coil.
A TP sensor is what type of sensor?
Potentiometer
What is the source of false air?
Punctured or loose air inlet hose
Which of the following parameters does a computer input sensor sense?
RPM
If the MAF sensor fails, the PCM uses ________ to calculate fuel delivery needs.
RPM and throttle position
A battery has just been changed on a popular European vehicle. What service should the technician perform before returning the vehicle to the owner?
Register the new battery to the vehicle
What does the PCM do to the torque convertor clutch when it detects rapid acceleration?
Release
Which of the following is a function of photodiodes?
Respond to various wavelengths of light
What is the first step of starter overhaul?
Restoration of a dirty and greasy starter to useful service.
_________ is created from the AC voltage from an alternator.
Ripple voltage
Which of the following is true of semiconductors?
Semiconductors are neither conductors nor insulators.
Which wire on a TP sensor should be back-probed to check the voltage signal to the PCM?
Signal
A defective battery causes which of the following symptoms?
Slow cranking
How are new slip rings attached to the rotor core during alternator rebuilding?
Soldered on
Which sensor is used to measure the position of the throttle?
TP sensor
Which among the following is the correct possible cause for application of the P0121 DTC?
TP sensor signal does not confirm with MAP
A battery high-rate discharge (load capacity) test is being performed on a 12-volt battery. Technician A says that a good battery should have a voltage reading of higher than 9.6 volts, while under load, at the end of the 15-second test. Technician B says that a battery conductance tester is often used to load the battery to two times the CCA rating of the battery. Which technician is correct?
Technician A only
A signal showing the voltage of a battery displayed on a digital storage oscilloscope (DSO) is being discussed. Technician A says that the display will show one horizontal line above the zero line. Technician B says that the display will show a line sloping upward from zero to the battery voltage level. Which technician is correct?
Technician A only
A technician connects one lead of a digital voltmeter to the positive (+) terminal of the battery and the other meter lead to the battery terminal (B) of the starter solenoid and then cranks the engine. During cranking, the voltmeter displays a reading of 878 millivolts. Technician A says that this reading indicates that the positive battery cable has too high resistance. Technician B says that this reading indicates that the starter is defective. Which technician is correct?
Technician A only
Technician A says that a voltage drop test of the charging circuit should only be performed when current is flowing through the circuit. Technician B says to connect the leads of a voltmeter to the positive and negative terminals of the battery to measure the voltage drop of the charging system. Which technician is correct?
Technician A only
Technician A says that distilled or clean drinking water should be added to a battery when the electrolyte level is low. Technician B says that fresh electrolyte (solution of acid and water) should be added. Which technician is correct?
Technician A only
Two technicians are diagnosing a poorly running engine. There are no diagnostic trouble codes. When the MAF sensor is unplugged, the engine runs better. Technician A says that this means that the MAF is supplying incorrect air flow information to the PCM. Technician B says that this indicates that the PCM is defective. Which technician is correct?
Technician A only
Two technicians are discussing the DC coupling setting on a DSO. Technician A says that the position allows both the DC and AC signals of the waveform to be displayed. Technician B says that this setting allows just the DC part of the waveform to be displayed. Which technician is correct?
Technician A only
A P0118 DTC is being discussed. Technician A says that the ECT sensor could be shorted internally. Technician B says that the signal wire could be open. Which technician is correct?
Technician B only
A V-6 is being checked for starter amperage draw. The initial surge current was about 210 amperes and about 160 amperes during cranking. Technician A says the starter is defective and should be replaced because the current flow exceeds 200 amperes. Technician B says this is normal current draw for a starter motor on a V-6 engine. Which technician is correct?
Technician B only
Network diagnosis is being discussed. Technician A says that a test light can be used at the DLC to determine if the CAN bus has activity. Technician B says that a break-out box can be used to determine if there is activity on the CAN bus. Which technician is correct?
Technician B only
Technician A says an analog scope can store the waveform for viewing later. Technician B says that the trigger level has to be set on most scopes to be able to view a changing waveform. Which technician is correct?
Technician B only
Two technicians are discussing a stepped ECT circuit. Technician A says that the sensor used for a stepped circuit is different than one used in a non-stepped circuit. Technician B says that a stepped ECT circuit uses a different internal resistance inside the PCM. Which technician is correct?
Technician B only
Two technicians are discussing the IAT sensor. Technician A says that the IAT sensor is more important to the operation of the engine (higher authority) than the ECT sensor. Technician B says that the PCM will add fuel if the IAT indicates that the incoming air temperature is cold. Which technician is correct?
Technician B only
Which of the following uses the cavity computer (signal) ground?
Terminal 5
After a TP sensor has been tested using the MIN/MAX function on a DMM, a reading of 5 volts is displayed. What does this reading indicate?
The TP sensor signal is shorted to 5-volt reference.
After a TP sensor has been tested using the MIN/MAX function on a DMM, a reading of zero volts is displayed. What does this reading indicate?
The TP sensor was open at one point during the test.
What is the next step after removing the brush end plate in starter overhaul?
The armature assembly is removed from the field frame.
Which of the following is true of battery load testing?
The condition of any battery is determined by the load test.
Which of the following is true about impurities?
The doping elements are called impurities.
What is the relationship between voltage drop and the resistance in the circuit?
The higher the voltage drop, the greater is the resistance in the circuit.
Why can stator windings not be tested if shorted?
The normal resistance is low.
In a star link network, a serial data line connects all of the modules to ________.
a central point
Faults or failures in electronic components could be caused by all of the following EXCEPT
a loose alternator belt
When the AC coupling position is selected, a capacitor is placed into the meter lead circuit, which effectively blocks __________.
all DC voltage signals
A transistor can __________.
amplify current
A meter used to measure amperes is called ________.
an ammeter
Slow cranking by the starter can be caused by all of these EXCEPT ______________.
an open neutral safety switch
The diodes are usually replaced _______.
as a replaceable rectifier component
Most ______ use MOSFETs.
automotive electronic circuits
The number of events, which require leads for each, is called a _______.
channel
A diode installed across a coil with the cathode toward the battery positive is called a(n) ____________.
clamping diode
The device that helps a CPU know when one signal ends and the other begins is called ____________.
clock generator
Computer speed is measured in ________________.
clock speed (Hz)
