Sensors/gauges Flashcards
What is a passive sensor
A sensor that do not use current supplied by ecm
Generates its own voltage
What is an active sensor
A sensor that uses current supplied by ecm
What is reference voltage
Regulated voltage supplied to sensors from the ecm (typically 5v DC)
What resistance does a switch have in the closed position
Zero resistance in the closed position
What resistance does a switch have in the open position
Infinite resistance in the open position
What is a single pole single throw switch
Simplest digital signal
Open or closed
Trans neutralizer switch
Clutch switch
Brake switch
Pto switch
What is a pull up switch
A switch that is connected between ecm and battery positive
What is a pull down switch
A switch that is connected between ecm and negative ground
What is a thermistor
Temperature sensitive variable resistor to measure temperatures
Two wire sensor changes resistance in proportion to Temperature
Where is plastic body thermistor used?
For air temperature applications
Where is a brass body thermistor used
For liquid temperature applications
What is a negative coefficient thermistor
Resistance decreases as temperature increases
What is a positive temperature coefficient thermistor
Resistance increases as temperature increases
What is a rheostat
Two wire variable resistance sensors
Uses variable sliding contact moving along a resistive wire
Where is a rheostat used?
Sending units
How is a three wire sensor configured?
Ground provided through ecm
Signal return
Positive voltage reference proportional to physical value measured
Are three wire sensors self diagnosing
Yes to an extent
What is a potentiometer
A sensor that uses three wires with the signal wire connected to a wiper or sliding contact moving across a resistive material
Where is a potentiometer used
Throttle position sensor
Measures travel of pedal
Idle validation switches do what
Uses two switches to verify correct accelerator pedal movement
Are dual path Throttle position sensors potentiometers?
Yes
What is a strain gauge
A sensor that measures small change in resistance of tiny wires embedded in tiny glass block.
Piezoresistive sensors
Rely on ability of certain mineral crystals to produce voltage or change resistance when compressed
What is a variable capacitance pressure sensor
A sensor that uses distance between two plates to measure pressure
