As the temperature increases, the resistance value of an NTC thermistor is reduced.
True
NTC thermistors are used more often than PTC thermistors on automobiles.
True
A knock sensor generates an A/C voltage.
True
Most O2 sensors operate at temperatures of 400˚F(204˚C) and above.
False. approx. 600˚F and above
An actuator's main purpose is to provide an input signal to the PCM and identify the conditions acting upon it.
False. actuator = output
When an engine is running lean, the voltage signal from the oxygen sensor will be low.
True
An engine coolant temperature sensor is an example of a
Thermistor
Which of the following is associated with voltage frequency?
Cycle
Hertz
A stoichiometric air/fuel ratio of (14.7:1) produces an oxygen sensor output voltage of
0.450 volts or 450mv
Which of the following is not a type of output actuator?
Switches
Actuators = solenoids, relays, control modules
Which of the following is not an acceptable way to test electrical circuits?
Piercing wires with T-pins.
Acceptable:
break-out box, backprobing, jumper wires
Tech A says a knock sensor is basically a Wheatstone bridge. Tech B says an engine coolant temperature sensor is basically a thermistor.
B only. knock sensor = piezoresistor
Tech A says voltage pulses to one coil or pair of coils in a stepper motor causes the motor to turn a specific number of degrees. Tech B says a permanent magnet motor has two wires.
Both
Tech A says some types of voltage sensors provide input to the computer by modifying a reference voltage signal. Tech B says some types of sensors provide a voltage generating signal.
Both
Actuators are being discussed. Tech A says they are variable resistance/reference types, switches, and thermistors. Tech B says they convert current into mechanical action
B only.
A _____ is an electrical switch that uses a control voltage with little current to control a high current load.
Relay
O2s testing being discussed. Tech A says a low voltage reading on a zirconium sensor should make the PCM add fuel. Tech B says a positive reading of STFT should be seen on the scanner.
Both
Actuators are being discussed. Tech A says that stepper motors contain two or more field coils and are powered by voltage pulses. Tech B says permanent magnets motors can rotate in opposite directions (reversible) by reversing the polarity of the wires.
Both
Waveform testing of a fuel injector is being discussed. Tech A says to connect the red lead of a DSO to the positive side of the circuit and the black lead of the labscope to the ground circuit. Tech B says to connect the red lead of the DSO to the ground circuit and black lead of the labscope to a good chassis ground.
