Question 1

Which of the following customer data programming options could be described as toggle options?

Accepted Answer

LS (Low Speed) or VS (Variable Speed) governing are toggle options because they allow the system to switch between two modes of operation, offering a binary choice similar to toggling a feature on or off.

Question 2

Technician A says that before performing proprietary reprogramming of an engine ECM, any fault codes should be cleared. Technician B says that in some cases following a proprietary data reprogramming procedure, a verification file has to be uploaded to the OEM data huB. ho is right?

Accepted Answer

Both technicians are correct. Clearing fault codes before reprogramming ensures that old errors do not interfere with the update process. Uploading a verification file after reprogramming is often required to confirm the update was successful and to maintain a record with the OEM.

Question 3

An engine management system that has adapted existing hydromechanical fueling devices for control by computer is known as:

Accepted Answer

A partial authority system refers to an engine management setup where the computer has control over traditional hydromechanical fueling devices, but not full control over the entire engine's operations.

Question 4

The non-volatile, read/write/erase memory component in a truck ECM is known as:

Accepted Answer

EEPROM (Electrically Erasable Programmable Read-Only Memory) is the correct answer because it is a type of non-volatile memory used in electronic devices, including truck ECMs (Engine Control Modules), for storing data that must be saved when power is removed. Unlike ROM or PROM, EEPROM can be erased and reprogrammed in blocks, making it suitable for read, write, and erase operations.

Question 5

Technician A says that some OEMs used the term flash memory to describe any type of programmable onboard memory. Technician B says that true flash memory transfers more quickly than EEPROM because it batched in blocks of bytes. Who is correct?

Accepted Answer

Technician A is correct because OEMs often use the term "flash memory" broadly to describe various types of programmable memory in vehicles. Technician B is also correct because flash memory does indeed transfer data more quickly than EEPROM (Electrically Erasable Programmable Read-Only Memory) due to its ability to write or erase data in blocks, rather than one byte at a time.

Question 6

What type of mass airflow (MAF) sensor measures pressure differential at two points either side of a venturi?

Accepted Answer

The critical flow venturi MAF sensor measures the pressure differential at two points either side of a venturi, which is a method used to determine the mass flow rate of air entering the engine.

Question 7

What is a stepper motor used for?

Accepted Answer

Stepper motors are used for precision positioning of a shaft due to their ability to move in discrete steps, allowing for precise control over movement and position.

Question 8

Which of the following is a disadvantage of a solenoid actuator when compared with a piezo actuator?

Accepted Answer

The answer of Which of the following is a disadvantage...

Question 9

In which of the following output devices would you be more likely to find a piezo actuator?

Accepted Answer

Electrohydraulic injectors (EHI) are more likely to use piezo actuators because piezoelectric materials can change shape very rapidly and with great precision when an electric current is applied, making them ideal for the precise control of fuel injection in modern engines.

Question 10

Technician A says that flash memory stores data in blocks of bytes rather than byte by byte. Technician B says that flash memory is slower to log data than EEPROM. Who is correct?

Accepted Answer

The answer of Technician A says that flash memory stores...

Question 11

Technician A says that the term flashing has come to mean any kind of programming to ECMs in the commercial vehicle industry. Technician B says that when new files are flashed to ECM memory, a verification file usually has to be uploaded to the OEM data hub to confirm the new programming. Who is correct?

Accepted Answer

Technician A is correct because "flashing" does indeed refer to the process of updating or reprogramming the electronic control modules (ECMs) in vehicles, which has become a common term in the industry. Technician B is also correct because, typically, after new software is flashed to an ECM, a verification process often involves uploading a file to the original equipment manufacturer (OEM) to confirm the update was successful and to maintain a record of the software version on the vehicle. This ensures that the vehicle's software is up-to-date and functioning as intended.

Question 12

Technician A says that Hall-effect throttle position sensors (TPS) are configurable to either digital or analog input circuits as required by the application. Technician B says that a disadvantage of Hall-effect TPS is that the contact wiper wears at an accelerated rate. Who is correct?

Accepted Answer

Hall-effect throttle position sensors (TPS) are configurable to either digital or analog input circuits as required by the application. However, a disadvantage of Hall-effect TPS is that the contact wiper wears at an accelerated rate.

Question 13

When processing the signal from an inductive pulse generator used to measure shaft rotational speed, which of the following is used to process the signal to an rpm value?

Accepted Answer

The signal from an inductive pulse generator, which varies with the rotational speed of the shaft, is essentially a frequency signal. The number of pulses per unit time (frequency) is directly proportional to the rotational speed, and thus, processing this frequency allows for the calculation of revolutions per minute (rpm).

Question 14

Which of the following best describes the operating principal of a critical flow venturi (CFV) used as a MAF sensor?

Accepted Answer

A critical flow venturi (CFV) operates on the principle of venturi and pressure differential flow. It measures the mass flow rate of air entering the engine by detecting the pressure differences created as air flows through a constricted passage.

Question 15

Where would a platinum resistance thermometer (PRT) most likely be found on a current truck?

Accepted Answer

A platinum resistance thermometer (PRT) is most likely found in the diesel particulate filter (DPF) to monitor and control the temperature for efficient operation and regeneration processes.

Question 16

When a stepper motor is driven by an 8 bit controller, how many 'steps' in the rotation can its rotor be positioned in?

Accepted Answer

An 8-bit controller can produce 2^8 = 256 distinct values, allowing the stepper motor to be positioned in 256 different steps throughout its rotation.

Question 17

When the piezo stack in a piezo-actuator is hit with an electrical trigger, which of the following best describes the time required for a mechanical response?

Accepted Answer

The mechanical response of a piezo stack in a piezo-actuator to an electrical trigger is almost instantaneous. This is because the piezoelectric effect, which is the principle behind the operation of piezo-actuators, involves the material changing shape or size immediately upon the application of an electrical voltage, without any significant delay.

Question 18

Technician A says that some types of NOx sensor use a galvanic operating principle. Technician B says that galvanic type NOx sensors must be powered up using V-Ref. Who is correct?

Accepted Answer

Technician A is correct because some NOx sensors indeed use a galvanic operating principle, which involves a chemical reaction generating a voltage that can be measured to determine NOx levels. Technician B is incorrect because galvanic cells, by their nature, generate their own voltage and do not require an external power source like V-Ref to operate.

Question 19

Technician A says that a WIF sensor uses a couple of probes that measure the dielectric properties of water versus that of fuel. Technician B says that dielectric properties refers to electrical resistivity. Who is correct?

Accepted Answer

Dielectric properties refer to the ability of a material to store electrical energy in an electric field. Electrical resistivity is a measure of the resistance of a material to the flow of electric current. While dielectric properties and electrical resistivity are related, they are not the same thing. A material with high dielectric properties will have low electrical resistivity, and vice versa.

Question 20

?What is a polyswitch?

Accepted Answer

A polyswitch is a PTC (Positive Temperature Coefficient) circuit protection device that increases resistance when a certain temperature is exceeded, thus limiting the current flow to protect the circuit.

Quiz 33: Vehicle Computer Systems