M09 Chapter 6 Input Sensor AUTI 131
The voltage signal supplied through the switch is either _________, or we could say the voltage signal is either high or low. This type of voltage signal is referred to as a digital signal. If the switch is turned on and off rapidly, a ______ digital voltage signal is applied from the switch to the bulb (Figure 6-13).
0 or 5 volts, square-wave
Digital signals are switched either fully on or fully off. If an ordinary on/off switch is connected to a 5-volt bulb and the switch is off, _____ is available at the bulb. When the switch is turned on, a _____ signal is sent to the bulb and the bulb is illuminated to _________. If the switch is turned off, the voltage at the bulb returns to 0 volt, and the bulb goes out.
0 volt, 5-volt, full brilliance.
When all four of the resistors have the same value, the bridge is balanced and the voltage sensor will have a value of _______. If the sensing resistor changes value, a change will occur in the circuit's ________.
0 volts, balance.
Binary coding
A group of numbers assigned to digital voltage signals.
Rotary-type throttle position (TP) sensor
A potentiometer with a pointer that is rotated by the throttle shaft that informs the PCM of throttle position by varying voltage.
Vehicle speed sensor (VSS)
A sensor that is usually mounted in the transmission and sends a voltage signal to the computer in relation to the vehicle speed.
Knock sensor (KS)
A sensor that sends a voltage signal to the computer in relation to engine detonation.
Feedback
A term used to describe a PCM's ability to control the activity of an actuator in response to input from sensors.
Negative temperature coefficient (NTC)
A thermistor that reduces its resistance as temperature decreases.
Exhaust gas recirculation (EGR)
A valve that dilutes the intake charge with spent exhaust in order to cool combustion chamber temperatures.
Digital voltage signal
A voltage signal that is either on or off, high or low.
Analog voltage signal
A voltage signal that is usually produced by input sensors and is continuously variable within a certain voltage range.
the magneto-resistive sensors are used in measuring rotation, such as in _____,______,____, and the like.
ABS braking, cam sensors, crank sensors
Engine coolant temperature (ECT) sensor
An input sensor that sends a voltage signal to the computer in relation to coolant temperature.
Manifold absolute pressure (MAP) sensor
An input sensor that sends a voltage signal to the computer in relation to intake manifold vacuum.
Oxygen (02) sensor
An input sensor that sends a voltage signal to the computer in relation to the amount of oxygen in the exhaust stream.
Fuel tank vapor pressure sensor
Informs the PCM of the pressure inside the fuel tank for EVAP system tests.
Linear Hall-effect TP sensor
It has the advantage of no contacts to wear or corrode and is even referred to as a noncontact TP sensor.
Throttle actuator control (TAC)
It is used to control the throttle opening by the PCM. It has often been called "throttle by wire."
Piezoresistive
Sensors that measure pressure changes.
Since the TP sensor is a very important component in the Throttle Actuator Control (TAC) system, also known as "throttle by wire," in this system there are often at least two __________ employed for improved _________.
TP sensors, accuracy.
Accelerator pedal position (APP) sensor
The APP sensor tells the exact location of the accelerator pedal.
Clutch pedal position (CPP) switch
The clutch pedal position (CPP) switch informs the computer that there is no load on the engine, as well as prevents the engine from starting unless the clutch is depressed.
Analog/digital conversion
The process of changing analog voltage signals to digital signals.
If the computer sends a command signal to actuate an output device, a feedback signal may be sent back from the ___________ to inform the computer that the task was performed. The feedback signal will confirm both the _________ of the output device and the operation of the actuator. Another form of feedback is for the computer to monitor voltage as a _____,_______, or other actuator is activated.
actuator, position, switch, relay
The ECM has the ability to watch engine operation through sensors. The computer can monitor the operation of __________ with sensors. Depending on the sensor input, the computer will control the actuator(s) until the programmed __________ are obtained.
actuators, results
As the wheel rotates, the vanes pass through the _______. When a shutter vane enters the gap, it intercepts the __________ and shields the Hall layer from its lines of force. The electrons in the supply current are no longer disrupted, and they return to a normal state. This results in _________ potential in the signal circuit of the Hall switch.
air gap, magnetic field, low voltage
The signal voltage leaves the Hall layer as a weak ________ signal. To be used by the PCM, the signal must be conditioned. It is first _________ because it is too weak to produce a desirable result. The signal is also ______ so that a low input signal is converted into a high output signal.
analog, amplified, inverted
Feedback means that data concerning the effects of the computer's _________ are fed back to the computer as an _______.
commands, input signal.
A magnetic pulse generator is also used to inform the _______ about the position of a monitored device. This is common in engine controls where the PCM needs to know the position of the ________ in relation to _________ degrees.
computer, crankshaft, rotational
The engine control module (ECM) receives inputs that it checks with programmed values. The inputs can come from other _______, from the ________, from the __________, or through a variety of sensors.
computers, driver, technician,
Voltage does not flow through a _________. Current flows while voltage is the pressure that pushes the ___________. However, voltage can be used as a ______. For example, difference in voltage levels, frequency of change, or switching from positive to negative values can be used as a signal.
conductor, current, signal
Reference voltage (vRef) sensors provide input to the computer by modifying or ____________ a constant, predetermined ____________. This signal, which can have a reference value from __________ volts, is generated and sent out to each sensor by a reference voltage regulator located inside the PCM.
controlling, voltage signal, 5 to 12
This action is repeated every time a tooth passes the _____. The moving lines of magnetic force cut across the ________ and induce a ______ signal.
core. coil windings, voltage
In an automotive computer, the microprocessor contains a large number of miniature switches that are capable of producing many_________ per second. A digital voltage signal, also called a square-wave signal, is used to control various ___________ in the system.
digital voltage signals, relays and components
All sensors perform the same basic function. They detect a mechanical condition (movement or position), chemical state, pressure, or temperature condition and change it into an ______________ that can be used by the computer to make ________. The PCM makes decisions based on information it receives from ________.
electrical signal, decisions, sensors.
Thermistors are used to monitor _______,___________, and ambient temperatures. By monitoring the thermistor's _____________, the PCM is capable of observing small changes in temperature.
engine coolant, intake air, resistance value
The MAP sensor is used to measure changes in ____________, which directly relate to ________.
engine vacuum, engine load.
A very similar sensor measures ______ pressure that is used by the _______ to help determine the presence of ______ in the evaporative control system (Figure 6-4).
fuel tank, PCM, leaks
Digital signals are switched either ________ . An analog voltage signal is continuously ________ within a certain range.
fully on or off, variable
Driver input signals are usually provided by momentarily applying a _________ through a switch. The computer receives this signal and performs the desired __________. For example, if the driver wishes to reset the trip odometer on a digital instrument panel, a reset button is depressed. This switch provides a momentary ground that the computer receives as an input and sets the trip odometer to zero. Some late-model vehicles use Hall-effect style switches that do not have mechanical contacts to wear over time.
ground, functions,
As TP sensor resistance varies, the computer is programmed to respond in a specific manner (e.g., ____________) to each corresponding voltage change.
increase fuel delivery or alter spark timing
Park neutral position (PNP) switch
informs the computer regarding gear selector position.
Regardless of the type of sensors used in electronic control systems, the computer is incapable of functioning properly without __________ from sensors.
input signal voltage
These sensors include components like the magnetic pulse generators, oxygen sensors (zirconium dioxide), and knock sensors (piezoelectric), which are capable of producing their own____________. This varying voltage signal, when received by the computer, enables the computer to __________ for changes in the computerized engine control system.
input voltage signal, monitor and adjust
We have explained that a digital signal is either high or low. A numeric value may be assigned to digital signals. For example, a ____________ may be given a value of 0 and a __________ may be given a value of 1. This assignment of numeric values to digital signals is called binary coding.
low digital signal, high digital signal
Magnetic pulse generators use the principle of __________ to produce a voltage signal. They are also called __________generators. These sensors are commonly used to send data to the computer about the _______ of the monitored component.
magnetic induction, permanent magnet (PM) ,speed
When varying internal resistance of the sensor allows ________ voltage to ground, the computer senses a _________ on a monitored signal line.
more or less, voltage change
The Hall layer has a __________ terminal connected to it. Two additional terminals located on either side of the Hall layer are used for the
negative and positive, output circuit.
When the magnetic field bisects the supply current flow, the electrons are deflected toward the Hall layer __________ (Figure 6-10). This results in a weak _________ being produced in the Hall switch.
negative terminal, voltage potential
If only the number of revolutions is required, the timing disc may have only _______ tooth, whereas if it is important to track quarter revolutions, the timing disc needs at least _______ teeth .The teeth will cause a voltage generation that is constant per _______ of the shaft.
one, four, revolution
The monitored signal line may be the _______ signal from the computer to the sensor (one- and two-wire sensors), or the computer may use a separate return line from the sensor to monitor _________(three-wire sensors). For example, consider the operation of the throttle position (TP) sensor.
output, voltage changes
A Hall-effect switch contains a _______ and a thin ___________ layer made of gallium arsenate crystal (Hall layer) and a shutter wheel.
permanent magnet, semiconductor
A steady current is applied to the crystal of the Hall layer. This produces a signal voltage that is __________ to the direction of ___________ and magnetic flux. The signal voltage produced is a result of the effect the magnetic field has on the electrons.
perpendicular, current flow
When a tooth approaches the core, a _________ current is produced as the magnetic field begins to concentrate around the _____. When the tooth and core align, there is no more expansion nor contraction of the magnetic field and the ______ drops to zero. When the tooth passes the core, the magnetic field expands and a _______ current is produced (Figure 6-8). The resulting pulse signal is sent to the PCM.
positive, coil, voltage, negative
The magneto-resistive sensor has advantages over the magnetic-reluctance sensor. The magneto-resistive sensor has its own _______, and, like the Hall-effect switch, the amplitude (strength) of the signal is not affected by the _________. The magnetic-reluctance sensor is not accurate at low speeds (Figure 6-11).
power supply, rotational speed
During acceleration (from idle to wide-open throttle), the computer monitors throttle plate movement based on the changing __________ returned by the TP sensor. The TP sensor is a type of variable resistor known as a rotary potentiometer that changes circuit resistance based on ____________ and speed of movement.
reference voltage signal, throttle shaft position
The PCM sends a _______ voltage to the thermistor, normally _____, through a fixed resistor. As the current flows through the thermistor to ground, voltage is dropped by the __________.
reference, 5 volts, thermistor.
As a tooth on the timing disc aligns with the core of the pick-up coil, it ______ the magnetic field. The magnetic field is forced to flow through the coil and _______ (Figure 6-6). When the tooth passes the core, the magnetic field is able to ________ (Figure 6-7).
repels, pick-up core, expand
A negative temperature coefficient (NTC) thermistor reduces its ___________ as temperature _________. This type is the most commonly used thermistor.
resistance, increases
A positive temperature coefficient (PTC) thermistor increases its ________ with an increase in ______. There are two basic types of thermistors: _________
resistance, temperature, NTC and PTC
Wheatstone bridges are one type of the component used in the manifold absolute pressure (MAP) sensor. The MAP sensor changes ________and therefore output ______ because of a membrane inside the sensor that is printed with piezoelectric strain gauges. The membrane responds to ______ either through a hose or is attached directly to the manifold itself (Figure 6-3).
resistance, voltage, manifold pressure
A thermistor is a solid-state variable resistor made from a ____________ material that changes resistance in relation to _________ changes.
semiconductor, temperature
Wheatstone bridges (Figure 6-2) are also used as variable resistance sensors. These are typically constructed of four resistors connected in_________ between an __________ terminal. Three of the resistors are kept at the same value. The fourth resistor is a sensing resistor.
series-parallel, input and ground
If the signal were off for more time than it was on, the motor would run at a ______; if it were on more than off, it would ________
slower speed, run faster.
For example, a vehicle speed sensor may be designed to deliver 4,000 pulses per mile. The number of pulses per mile remains constant regardless of ___________. The computer calculates how fast the vehicle is going based on the __________ of the signal. The timing disc is also known as an armature, reluctor, trigger wheel, pulse wheel, or timing core.
speed, frequency
It is then sent through a Schmitt trigger, which is a type of A/D converter, where it is digitized and conditioned into a clean ________ signal. The signal is finally sent to a switching transistor. The computer senses the turning on and off of the switching transistor to determine the ______ of the signals and calculates the ______.
square wave, frequency, speed
The distributor pick-up coil is also known as a stator, sensor, or pole piece. It remains ___________ while the timing disc rotates in front of it. The changes of magnetic lines of force generate a small __________ signal in the coil. A pick-up coil consists of a __________ with fine wire wound around it.
stationary, voltage, permanent magnet
In addition to variable resistors, another commonly used reference voltage sensor is a _______. By opening and closing a circuit, switches provide the necessary ________ information to the computer so that vehicles can maintain the proper __________.
switch, voltage, performance and drivability.
The Hall-effect switch operates on the principle that if a current is allowed to flow through _____ conducting material that is exposed to a __________, another _____ is produced (Figure 6-9).
thin, magnetic field, voltage
The major components of a pulse generator are a _____ and a _____________. The timing disc is attached to a ___________. The number of teeth on the timing disc is determined by the manufacturer and the application.
timing disc, pick-up coil, rotating shaft or cable,
An air gap is maintained between the ______ and the _________ coil. As the timing disc rotates in front of the pick-up coil, the generator sends a _________ (Figure 6-5).
timing disc, pick-up, pulse signal
The microprocessor can vary the length of time that the digital signal is high or low for precise control (Figure 6-14). Pulse width is the amount of time the signal is _______. For a computer to produce a ________ output—for example, to control a blower motor speed—the computer can turn the _________ on and off rapidly, with varying amounts of on time.
turned on, varying, output voltage
The word binary means _______, and in the binary coding system the two values are ______ (Figure 6-15). In an automotive computer, information is transmitted in binary code form. Conditions, numbers, and letters can be represented by a series of zeros and ones.
two values, 0 and 1,
Each sensor used in a particular system has a specific job to do (e.g., monitor throttle position, vehicle speed, and manifold pressure). Together these sensors provide enough information to help the computer form a complete picture of ____________. Even though there are a variety of different sensor designs, they all fall under one of two operating categories: _________ sensors or __________ sensors.
vehicle operation, reference voltage, voltage-generating
This data provides information about ______ speed, _____ speed, and _____ speed. The signals from speed sensors are used for instrumentation, cruise control systems, antilock brake systems, ignition systems, speed-sensitive steering systems, and automatic ride control systems.
vehicle, shaft, wheel
The Hall effect sensor requires a ___________ source along with an output lead. The Hall effect sensor produces a ________ with a constant signal amplitude
voltage and ground, digital output
A computer is capable of reading _______ signals. The programs used by the PCM are "burned" into ______ using a series of numbers.
voltage, IC chips
It modifies a ________ to or from the computer, indicating a constantly changing status that can be ________, compensated for, and ______. That is, this sensor simply modifies a voltage signal from the computer.
voltage, calculated, modified
Because the computer knows that a certain _________ value has been sent out, it can indirectly interpret things like ________,________ and component position based on what comes back.
voltage, motion, temperature,
The sensing circuit will receive a _____ reading that is proportional to the amount of ________ change. If the Wheatstone bridge is used to measure temperature, temperature changes will be indicated as a change in _______ by the sensing circuit. Piezoresistive devices are used to measure ________ changes when used in conjunction with a Wheatstone bridge.
voltage, resistance, voltage, pressure
Changing positions of an actuator should result in predictable changes in the computer's ___________ circuit. The computer may set a diagnostic code if it does not receive the correct _________ signal. The PCM can also monitor how fast the ______ is moved and can alter fuel injection accordingly.
voltage-sensing, feedback, throttle
A ___________circuit compares the voltage sent out by the PCM to the voltage returned to the PCM and determines the ________.. Using its programmed values, the computer is able to translate the voltage drop into a ___________ reading.
voltage-sensing, voltage drop, temperature
These numbers represent various combinations of _______ that the computer can understand. The voltage signals to the computer can be either _______.
voltages, analog or digital.
The shutter wheel consists of a series of alternating _________. It creates a magnetic shunt that changes the strength of the ________ from the permanent magnet. The shutter wheel is attached to a rotational component.
windows and vanes, magnetic field
To diagnose thermistors accurately, you must be able to identify the type by looking at a _________ in the service information.
wiring diagram or chart
Switches can be used as an input for any operation that requires only a _______ or ______ condition. Other inputs include those supplied by means of a _________ and those signals returned to the computer in the form of feedback.
yes-no, on-off, sensor
When a rheostat is used to control a 5-volt bulb, the rheostat voltage may be anywhere between _______ volts. If the rheostat voltage is low, a small amount of ______ flows through the bulb to produce a dim light from the bulb. If the rheostat voltage is 5 volts, higher _______ flow produces increased light brilliance. As the rheostat voltage is ________, the light becomes dimmer. This is an example of an analog voltage (Figure 6-12). Many of the sensors in an automotive computer system produce analog voltages.
0 and 5, current, decreased