diesel electrical chapter 20
What is the amount of voltage typically supplied by the ECM to sensors? -3 colts -5 volts -7 volts -10 volts
5 volts direct current
Which of the following is NOT correct concerning potentiometers? -potentiometers are similar to rheostats in that they vary signal voltage depending on the position of a sliding contact or wiper moving across a resistive material -they are three wire sensors with the signal wire connected to the internal wiper -a common application of a potentiometer is a position sensor such as the throttle position sensor(TPS) -potentiometers supply digital data to processing circuits.
D (potentiometers supply analog data to processing circuits)
Which of the following are examples of sensors used in today's commercial vehicles? -position sensors for wheel speed, camshafts, crankshafts and pedal position -pressure sensors for engine oil fuel crankcase and intake boost -coolant level sensors -all of these
all of these
Which of the following conditions are thermistors monitored for? -resistance to validate normal signal voltage and detect out of range faults -opens either internal or in the circuit wiring -shorts to power -all of these
all of these
Which of the following is correct concerning mass airflow (MAF) sensors? -the mass airflow sensor is a device that measures the weight of air entering the engine intake -MAF sensors are common on engines operating at stoichiometric air fuel ratios -on the diesel engines operating with an excess air ratio, the MAF is used as part of the heavy duty onboard diagnostics component monitor for the EGR -all of these
all of these
Which of the following is correct concerning the strain gauge? -a strain gauge measures small changes in the resistance of tiny wires caused by stretching or contraction -construction of this type of pressure sensing device uses resistive wires called strain gauge wires embedded in a flexible glass block -Wheatstone bridge electrical circuit which measures changes in resistance of an unknown variable sensor is uses to measure this small change in resistance of the strain gauge wires -all of these
all of these
Technician A says a thermistor is a temperature-sensitive variable resistor commonly used to measure coolant, oil, fuel, and air temperatures. Technician B says the name itself combines the words thermal and resistor. Who is correct?
both A and B
Technician A says an oil pressure switch is an example of a switch being used as a sensor. Technician B says a coolant level sensor is not an example of a switch being used as a sensor. Who is correct?
both A and B
Technician A says soot sensors are particulate sensors that measure any soot present in the exhaust. Technician B says the soot sensor is a type of variable capacitance sensor that uses soot to change the dielectric strength between two charged plates. Who is correct?
both A and B
Technician A says the comprehensive component monitor (CCM) is a continuous monitor that constantly checks for malfunctions in any engine or emission-related electrical circuit or component providing input or output signals to an ECM. Technician B says electrical inputs and outputs are evaluated for circuit continuity and shorts by measuring voltage drops in a circuit. Who is correct?
both A and B
Technician A says three-wire circuits, whether digital or analog, passive or active, use a reference voltage, signal, and ZVR wire. Technician B says the ZVR wire is also referred to as ground return by some manufacturers. Who is correct?
both A and B
Technician A says the idle validation switch (IVS) is a commonly used throttle safety system. Technician B says the accelerator position sensor (APS) is a safe device and no additional safeguards are possible. Who is correct?
technician A (manufacturers will build additional safety system to verify throttle position)
Technician A says injectors will use solenoids to meter fuel and adjust the timing of injection events. Technician B says relays inside the ECM are most often used to open or close circuits controlling these operators. Who is correct?
technician A (transistors inside the ECM)
Technician A says the Charles Law states the sum of the voltage drops in a circuit equals source voltage. Technician B says when two resistors are connected in series, the greatest voltage drop takes place across the resistor with the highest resistance. Who is correct?
technician B (Kirchhoff's law)
Technician A says ammonia sensors are currently used on gasoline engines but may be available for diesel engines in the future. Technician B says voltage generators are a category of sensors that is passive and produces an analog signal of varying voltage or AC frequency. Who is correct?
technician B (more frequently used on diesels)
Technician A says Hall effect sensors produce analog signals. Technician B says Hall effect sensors are commonly used to measure the rotational speed of a shaft. Who is correct?
technician B (producing a digital square waveform)
Technician A says evenly spaced reluctor ring teeth or lugs, however, will identify the cylinder stroke position. Technician B says a seventh tooth or lug on the cam gear of a six-cylinder engine could correspond to TDC of the first cylinder's compression stroke. Who is correct?
technician B (will not identify the cylinder)
