final exam study guide

Emission standards established for off-road diesels began in

1994

How many possible steps of positions do most stepper gauges have?

3,060

The unipolar stepper motor can be identified by its _____ wires that connect _____ field coils.

5 or 6; 4

"Bit" is a shortened term for binary digit; a byte is a combination of _______ bits.

8

Which of the following is NOT correct concerning duty cycle?

A 100% duty cycle means the signal is off.

What terminals of the 9-pin diagnostic connector are connected to a digital multimeter (DMM) to check the resistance of the terminating resistors used for the CANbus?

C and D

Self-diagnostic capabilities are referred to as which of these?

OBD

Which of the following is NOT correct concerning selfdiagnostic capabilities?

The presence of faults is unable to be communicated through the malfunction indicator lamps.

This type of fault is currently taking place and is uninterrupted in action

active

Which type of input sensor is used by the engine management system and uses power supplied by the machine's ECM?

active

Which of the following statements about information reporting capabilities is correct?

all choices

Which of the following statements about safety is correct?

all choices

Analog signals can have a changing value of ________.

all choices are correct

What are some examples of outputs of the electronic control assembly?

all choices are correct

Which of the following is a benefit of electronic control?

all choices are correct

Which of the following statements about instrumentation is correct?

all choices are correct

Which of the following statements about the prove-out sequence is correct?

all choices are correct

Which of the following statements about two- and three coil movements is correct?

all choices are correct

Mechanical gauges depend upon _______ to operate.

all of the choices are correct

How much voltage is supplied to gauges and sending units?

between 5 and 10 volts

Which of the following is NOT a technology used with common gauge systems?

bi-electrical

All electronically controlled engines and powertrain components have built-in self-diagnostic capabilities. To communicate this data to an electronic service tool from even a single module requires the use of

bidirectional communications

What type of data is collected by the sensing functions of the electronic control system?

both a and b

Which of the following statements about analog to digital (AD) conversion is correct?

both a and b

Technician A says speedometers electronically measure the driveshaft speed by counting a series of electrical pulses produced per mile or kilometer of distance traveled. Technician B says two wires connecting the instrument panel gauge clusters to the CAN network are all that is necessary to supply the data necessary to display machine data and trip information, provide fault codes, and display warning lamps. Who is correct?

both tech a and tech b

Technician A says that a knock sensor measuring abnormal combustion signals is a common application of piezoresispull tive sensors. Technician B says that silicon-based piezoresistive sensors are very sensitive to slight pressure changes. Who is correct?

both tech a and tech b

Technician A says that a pulse-width-modulated electrical signal is an electrical signal that shares similar characteristics with both a digital signal and an analog signal. Technician B says that common examples of devices using PWM signals are solenoids, injectors, and light circuits. Who is correct?

both tech a and tech b

Technician A says that a system identifier (SID) indicates a specific failed component. Technician B says that a parameter identifier (PID) is a value or identifier of an item being reported with fault data. Who is correct?

both tech a and tech b

Technician A says that broken mechanical systems are often diagnosed visually or with mechanical tools such as pressure gauges and dial indicators. Technician B says that self-monitoring or self-diagnostic capabilities are, therefore, built into electronic control systems to help technicians perform faster. Who is correct?

both tech a and tech b

Technician A says that diesel engines were the first machine systems transformed by electronic controls. Technician B says that smarter engines deliver ever-increasing power from smaller displacements. Who is correct?

both tech a and tech b

Technician A says that electronic control systems use a variety of sensors, wires, electrical actuators, and electronic modules moved with invisible electrical signals. Technician B says that the three major divisions of electronic control systems are sensing, processing, and output. Who is correct?

both tech a and tech b

Technician A says that if a problem is related to temperature, vibration, or moisture, the circuit or control module can be heated, lightly tapped, or even sprayed with water to simulate the failure conditions. Technician A says that a graphing meter with glitch testing capabilities can identify and record a circuit fault in microseconds. Who is correct?

both tech a and tech b

Technician A says that most machine systems operate with at least some degree of electronic control. Technician B says that understanding the operating principles of electronic control systems is fundamental for choosing diagnostic strategies. Who is correct?

both tech a and tech b

Technician A says that out-of-range faults check sensor voltages and, in a few cases, current draw to determine whether the sensor or associated circuits are open or have shorts. Technician B says that rationality faults use a detection strategy whereby the validity or accuracy of sensor data is evaluated by comparing sensor voltages with expected values. Who is correct?

both tech a and tech b

Technician A says that processing refers to the control system element that collects sensor data and determines outputs based on a set of instructions or program software. Technician B says that operational algorithms are included in the software that determines the steps taken when processing electrical data. Who is correct?

both tech a and tech b

Technician A says that switches are categorized as sensors whenever they provide information to an electronic control system. Technician B says that switch data may indicate a physical value such as open or closed, up or down, or high or low, or it may indicate on and off. Who is correct?

both tech a and tech b

Technician A says that the suspect parameter number (SPN) combines elements of J-1957 PIDs and SIDs. Technician B says that the SPN is used for multiple diagnostic purposes. Who is correct?

both tech a and tech b

Technician A says that wide-band oxygen sensors produce a voltage proportional to a specific exhaust gas oxygen level. Technician B says that oxygen sensors are used to measure air-fuel ratio in order to calibrate EGR flow rates and air-fuel ratios for exhaust after treatment devices. Who is correct?

both tech a and tech b

Technician A says the malfunction indicator lamp (MIL) and check engine lamp (CEL) will illuminate for approximately three to five seconds during engine start-up and then extinguish. Technician B says if there are active fault codes, the lights will switch back on after start-up. Who is correct?

both tech a and tech b

Technician A says warning lights can be built into gauges or mounted in a dedicated panel in the instrument. Technician B says warning lights require a power feed and ground for the light to illuminate. Who is correct?

both tech a and tech b

Technician A says you should use an ohmmeter when checking for smooth operation of a fuel sender unit. Technician B says the fuel sender unit should be reconnected to the fuel gauge to check for full-range operation only after removing it from the tank. Who is correct?

both tech a and tech b

Two technicians are discussing J-1939 fault code construction. Technician A says that to prevent message signals from canceling out one another, signal collisions are avoided through an arbitration process. Technician B says that high priority is used for control situations that require prompt action in order to provide safe vehicle operation. Who is correct?

both tech a and tech b

Two technicians are discussing engine management input sensors. Technician A says that switches are the simplest sensors of all because they have no resistance in the closed position and infinite resistance in the open position. Technician B says that a zero-volt signal would present as a closed switch, while 12 volts would present as an open switch. Who is correct?

both tech a and tech b

Two technicians are discussing machine serial data communication and networks. Technician A says that data carried on the CANbus has four distinct message formats: data frame, remote frame, error frame, and overload frame. Technician B says that cell phone and Bluetooth technology are two levels of customization realized using a wireless network interface. Who is correct?

both tech a and tech b

Two technicians are discussing machine serial data communication. Technician A says that the advantages of multiplexing include software control of the electrical system, enabling onboard diagnostics, the ease of connecting electronically controlled accessories and features, and areduction in the number of sensors. Technician B says that controlled area networks are the most widely used type of network for integrating powertrain operation of all the latest machines. Who is correct?

both tech a and tech b

Two technicians are discussing variable reluctance sensors. Technician A says that a broken magnet in the sensor will cause a low voltage reading. Technician B says that excessive air gap between the sensor and reluctor will cause sensor output failure. Who is correct?

both tech a and tech b

When paired together and connected in parallel to all modules in the network, the typology forming the communication pathway is called a

bus

To make sure that an engine fuel system drivability malfunction is identified and repaired correctly, always refer to

diagnostic trouble codes

What is an unknown and uncontrolled input acting on the OBD system?

disturbance

Which of the following is the most common method of illuminating warning lights in today's machines?

electronic switches

In the OBD system, a __________ is a deviation of at least one characteristic property of the system from its standard behavior.

fault

____________ is/are an adaptive strategy that reconfigures the system operation or substitutes suspect data with default data to maintain normal system functionality even with the fault.

fault accommodation

Which of these sensor designs has the advantage of producing a digital signal square waveform and has strong signal strength at low shaft rotational speeds?

hall effect

What type of OBD fault is not ongoing and can be both active and historical?

intermittent

Which of these is LEAST LIKELY to be used as a potentiometer in a diesel engine management system?

mass airflow sensor

The OBD (onboard diagnostics) system can take one of two self-diagnostic approaches to identifying faults. The system can either use traditional self-diagnostic strategies or use

model based approach

A message identifier (MID) identifies which ________ is reporting the fault.

module

Data from a sensor as simple as the coolant temperature are even more critical to operation because ________ that evaluate emissions-control devices will run only after an engine has reached operating temperature.

monitors

All networks have in common the concepts of interconnected modules. The use of _______ enables digital communication between each module and time division multiplexing as a communication strategy.

multiplexing

Communication between all the modules and devices in a machine that is connected to a network that uses an electrical signal-processing strategy is called which of these?

multiplexing

Technician A says a suspect parameter number (SPN) is a fault code used by J-1587 protocols that identifies which subsystem has failed. Technician B says a system identifier (SID) is a numerical identifier that defines the data in a fault message and the priority of the fault. Who is correct?

neither tech a nor tech b

Two technicians are describing the use of electronic service tools. Technician A says that all fault codes, communication language, and other features of the onboard network are standardized by EPA legislation. Technician B says that only the equipment manufacturer's specific scan tool or software can read the legislated fault codes. Who is correct?

neither tech a nor tech b

Technician A says that, in contrast to analog signals, digital signals vary greatly in voltage, frequency, or amplitude. Technician B says that the binary code does not lend itself to use in microprocessor circuits, where processing large amounts of alphabetic or numerical data, represented in strings of 0s or 1s, is performed. Who is correct?

neither tech a or tech b

The rules or standards used to communicate over the networks are called

network protocol

Electronic control modules can easily evaluate the voltage and current levels of circuits to which they are connected and determine whether the data makes sense and is in the correct operational range. These self-diagnostic capabilities are referred to as which of these?

obd

A ________ switch is connected between the ECM and a negative ground current potential.

pull down

_________ voltage is a precisely regulated voltage supplied by the ECM to sensors.

reference

System self-diagnostic checks are generally performed by limit checking of __________ or circuit data.

sensors

When using networks, electrical system complexity is absorbed by the ________ instead of a huge array of hardwired components and circuit boards

software

Which of these devices measures small changes in the resistance of tiny wires caused by stretching or contraction?

strain guage

Technician A says electrical problems such as a blown fuse, faulty wiring, gauges, or sender units can result in a faulty gauge reading. Technician B says machines use only one type of gauge sending unit. Who is correct?

tech a

Technician A says normally closed pressure switches opened with air or oil pressure provide a path to ground to illuminate a bulb. Technician B says normally opened pressure switches opened with air or oil pressure provide a path to ground to illuminate a bulb. Who is correct?

tech a

Technician A says stepper motor gauges reduce the problems associated with inaccurate readings from bimetallic and electromagnetic coil gauges caused by voltage fluctuations. Technician B says stepper motors are brush-type DC electromechanical devices that generally use a permanent magnet shaft that is surrounded by more than two pairs of electromagnetic coils. Who is correct?

tech a

Technician A says that J-1939 uses the CANbus protocol, which permits any electronic control module to transmit a message over the network. Technician B says that J-1939 still uses parameter identifier (PID) as a value or identifier of an item being reported with fault data. Who is correct?

tech a

Technician A says that a defective mass airflow sensor can be diagnosed by using a graphing meter and inspecting the waveform that it produces. Technician B says that only the ECM can identify a faulty sensor. Who is correct?

tech a

Technician A says that a fault is a deviation of at least one characteristic property of the system from its standard behavior. Technician B says that a historical fault took place at one time and can never be active again. Who is correct?

tech a

Technician A says that disconnecting a high-bias sensor will likely produce the fault code description "voltage high or shorted high." Technician B says that the fault code most likely reported by a disconnected high-bias sensor is "voltage low or shorted low." Who is correct?

tech a

Technician A says that serial data is used to transmit information from one electronic module to another. Technician B says that baud rate refers to the number of data bits transmitted per minute. Who is correct?

tech a

Technician A says that some manufacturers may use their own codes because they are not bound to CANbus. Technician B says that all manufacturers must use CANbus. Who is correct?

tech a

Technician A says that technicians can take advantage of programmable electronic controls. Technician B says that power and torque-rise profiles cannot be altered electronically. Who is correct?

tech a

Technician A says that telematics uses specialized telecommunication applications for the long-distance transmission of information to and from a machine. Technician B says that telematics is not capable of transmitting information on fault codes. Who is correct?

tech a

Technician A says that wires are twisted to minimize electromagnetic interference caused by magnetic fields and radio waves. Technician B says that network signals will never be distorted and slowed if terminating resistors are missing or defective. Who is correct?

tech a

Two technicians are discussing J-1939 fault code construction. Technician A says that parameter group number (PGN) information includes commands, data, requests, acknowledgments, and negative acknowledgments, and fault codes. Technician B says that parameter group number (PGN) information includes commands, data, and requests only. Who is correct?

tech a

Two technicians are discussing OBD for machines. Technician A says that the simplest, most familiar definition is the diagnostic function of electronic control systems to identify or self-diagnose system faults and report fault codes. Technician B says the OBD will only send blink codes to the display. Who is correct?

tech a

Two technicians are discussing checking the voltage at the 9-pin diagnostic connector or datalink connector (DLC). Technician A says that voltage is checked with the ignition on at terminals C and D. Technician B says that the voltage at terminals C and D should be at least 12.6 volts. Who is

tech a

When inspecting for shorts on the CANbus, Technician A says that neither CAN-H nor CAN-L should have continuity with chassis ground. Technician B says that only the CAN-L should have continuity with ground. Who is correct?

tech a

Technician A says that disconnecting modules one by one can help identify a module that is shorting out the CANbus. Technician B says that the best diagnostic routine to identify a network problem is to perform resistance and voltage checks of the CANbus at the DLC. Who is correct?

tech a and tech b

Technician A says gauge senders output an electronic signal based on an electrical input. Technician B says electronic modules are available to convert variable voltage values into digital signals for use by digital gauges. Who is correct?

tech b

Technician A says that a bench signal is one type of electrical signal commonly used in electronic engine control applications. Technician B says that an analog signal is one type of electrical signal commonly used in electronic engine control applications. Who is correct?

tech b

Technician A says that after the engine starts and the alternator begins charging, charging system voltage is applied to both terminals of a bulb. Technician B says the charging system indicator light is an example of a light operated through voltage drop. Who is correct?

tech b

Technician A says that if a gauge does not respond during a prove-out sequence, a blown fuse is the problem. Technician B says erratic gauge readings could be caused by resistive grounds. Who is correct?

tech b

Technician A says that in serial communication, one wire, called CAN-H, has a more negative voltage than the other, which is CAN-L. Technician B says that each wire will have a mirror opposite charge of the other when communication takes place. Who is correct?

tech b

Technician A says that passive sensors are not used in today's machine management systems. Technician B says that active sensors use current supplied by the ECM to operate. Who is correct?

tech b

Technician A says that to check for fault codes, only a scanner or personal computer connected to the data link connector can retrieve codes. Technician B says that fault codes could also be retrieved from an instrument cluster display. Who is correct?

tech b

technician A says that an incipient fault is not ongoing and can be both active and historical. Technician B says that an incipient fault is a fault that is the result of system or component deterioration. Who is correct?

tech b

A two-wire sensor that changes resistance in proportion to temperature is called a

thermistor

hat requires the modules and other devices to take turns, sharing the data bus communication pathway?

time division multiplexing

The use of a reference voltage is important in engine computer processor operation, because the value of the variable resistor can be calculated by measuring which of these values when another resistor with a known voltage input is connected in series with the variable resistor?

voltage drop

Consider an active-type pressure sensor that uses a pulldown resister to identify signal faults. What fault code will likely be reported if the Vref wire is broken?

voltage high or shorted high

What is an example of a gauge that can use D'Arsonval movement?

voltmeter