Deck 11: Sensors, Digital Electronics, and Multiplexing

Question 1

A Wheatstone bridge is used to convert an AC voltage into a DC voltage.

Answer 1

False

Question 2

All temperature sensors are classified as thermocouples.

Answer 2

True

Question 3

A variable capacitance pressure sensor determines pressure by a change in capacitance as the pressure being measured causes a change in the distance between the two plates of a capacitor.

Answer 3

True

Question 4

Volatile memory would typically be lost (cleared) when the power supply is disconnected.

Question 5

Referring to the figure shown below, closing the switch in the circuit with the 1k ohm resistor with all the other switches open would result in 12V referenced to ground measured at the A/D input.

Question 6

Referring to the following figure, this is an example of time-division multiplexing.

Question 7

The 120 ohm characteristic impedance of J1939 cable can be measured with a DMM ohmmeter.

Question 8

Referring to the figure shown below, a shorted to ground circuit between the relay coil and the low side driver would cause the air fan clutch solenoid to be energized.

Question 9

Which of the following would most likely NOT be a temperature sensor?

A) Thermistor
B) RTD
C) Thermocouple
D) Hall effect sensor

Question 10

Technician A says that a damaged thermocouple wire should be repaired using a splice clip with solder and heat shrinkable tubing. Technician B says that most anti-lock brake systems use a strain gauge sensor to detect wheel speed. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 11

A _____ would most likely be used to determine accelerator position.

A) potentiometer
B) rheostat
C) strain gauge
D) PRT

Question 12

Technician A says that a variable reluctance sensor may be used to determine engine crankshaft position. Technician B says that a variable reluctance sensor may be used to determine engine crankshaft speed. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 13

Referring to the following figure, closing all four switches at the same time would cause ____ at the A/D input referenced to ground.

A) more than 6V
B) 12V
C) less than 6V
D) more than 8V

Question 14

Technician A says that the amplitude of the output voltage of a variable reluctance sensor is dependent upon the sensor air gap. Technician B says that the output voltage of a variable reluctance sensor is dependent upon the rotational speed of the target. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 15

Which of the following is a true statement?

A) The engine control module (ECM) is always in charge of a CAN network.
B) The parameter group number (PGN) indicates the type of module that is transmitting a J1939 message.
C) A J1939 SPN is similar to a J1587 PID.
D) All of the above are true statements.

Question 16

An electronic module digital input that is internally-pulled down would most likely be connected to which of the following?

A) A variable reluctance sensor
B) A switch that when closed provides a positive voltage to the electronic module input terminal
C) A switch that when closed provides a ground for the electronic module input terminal
D) Battery positive terminal

Question 17

Referring to the figure below, technician A says that if the resistance of the engine coolant temperature sensor is 1k ohms, the voltage at the A/D input terminal would be 2.5V reference to ground. Technician B says that if the fan override switch is closed, the voltage at the microprocessor Input A would be 12V. Who is correct?

A) A only
B) B only
C) Both A and B
D) Neither A nor B

Question 18

Referring to the figure shown below, an open circuit between the engine coolant temperature sensor and the 1k ohm pull-up resistor would result in ___ at the A/D input referenced to ground.

A) 0V
B) 2.5V
C) 5V
D) 12V

Question 19

An AND gate is most like which of the following?

A) Two resistors connected in parallel
B) Two switches connected in series
C) Two switches connected in parallel
D) Three switches connected in series-parallel

Question 20

___ describes the relationship between the output of a sensor and the physical variable being measured such as pressure or temperature.

A) Multiplexing
B) Impedance
C) Floating impedance
D) Transfer function