Ch. 1
What sensor measures pressure in which it creates it's own voltage?
Pezoresistive pressure sensors
the brightness of a bulb is rated in what ? and what was it changed to?
candle power, lumens
What are used to absorb a surge of electrons from a collapsing magnetic field and to stabalize voltage fluctuations in a circuit?
capacitors
What word is used to commonly describe the wires and other components used in an electrical system?
circuit
what is used to provide a signal to identify the position of cylinder number one?
crankshaft position sensor
The two terminals located in a rheostat complete the circuit that varies the __________.
current flow
A negative temperature coefficient, or NTC, thermistor will increase it's ____________ as ___________________ goes _______________
resistance, temperature, down
Digital voltage occurs in one or two states what are those?
on, off. high or low, 0 or 1
where do each terminals connect to on a rheostat?
one terminal connects to the fixed end of the resistor and one terminal connects to a moveable contact
what type of potentiometer is an electromechanical device that tracks movement of a component and relays information back to a control module in the form of a voltage signal?
position sensor
output or a load has to have what two things?
power and ground
what are the three terminals there for in a potentiometer?
reference voltage, signal, and signal return
When turning the rheostat, the sliding contact moves further away from the fixed contact creating greater resistance. What happens next?
The instrument panel lights dim.
with the bulb what makes contact with the positive terminal of the socket.?
The terminal (the bottom most portion of the bulb)
What are almost always used as temperature sensors. Also they come in two types and are classified based on their reaction to temperature. and they also work automatically when working.
Thermistors
your four band resistor has a reading of 4 on one band and 0 on the second band. this gives you a combined value of 40. your multiplier value from your third band reads 10 and so you now know your ohm reading is 400. your tolerance band is +or-5% what does that mean?
This means this resistor can be over or under 5% of 400 ohms. This means it should read between 380 and 420 ohm when measured with a DMM
vehicle devices that measure change in position, temperature and rotation will often use analog circuits to transmit the information. What's an example with engine coolant? how does that process work?
When the temperature rises above 95 degrees the temperature will affect the resistance in the coolant sensor, altering the voltage being sent to the engine control module, or ECM. The ECM will then respond to this by turning the fan on. When the temperature falls below again, the ECM will turn off.
Technician A says that only one resistor is used for one LED in an LED headlamp. Technician B says that multiple resistors can be used for one LED in an LED headlamp. Which technician is correct?
a
Technician A says that the bulbs used in interior lighting applications are a higher wattage than those used for instrument cluster illumination. Technician B says that HID bulbs use a filament.Which technician is correct?
a
What is built into the control module helping turn the analog signal into a digital one?
a converter
which resistor has a set resistance value measured in ohms. This set resistance value is the amount of resistance in which it was manufactured to have
a fixed resistor
They are low current monitoring devices used to determine a component's position.
a potentiometer
is a three-terminal variable resistor with a movable center connection.
a potentiometer
tracking devices like accelerator pedal position sensor, or APP, the exhaust valve position sensor, or EVP, or the throttle position sensor, brake travel sensor are all examples of applications that use a what?
a potentiometer
in heated window and heated mirror applications a __________ is used to control the circuit
a relay
what type of variable resistor would be necessary to control the amount of lighting needed in the interior of a vehicle?
a rheostat
What is the converter going to turn the analog signal into in order for it to become digital?
a series of binary numbers
when used as a circuit protection for on-board computers, a fixed resistor protects against what?
a short to ground
The example of a microphone converting sound into an analog signal that is then sent through a circuit into an amplifier. The amplifier then taking that signal and modifying it so that it can be used by the speakers to produce sound. is an example of what type of signal ?
analog
Unless a signal is digital a signal is considered?
analog
What type of signal is used to measure a response to changes in the environment outside a device
analog
a signal that varies in both frequency and amplitude
analog signal
can be viewed as a sine wave
analog signal
can vary over a given range
analog signal
what signal can change over a given range. Changing the frequency and voltage.
analog signal
Technician A says that a potentiometer has two terminals. Technician B says a position sensor is used to measure the position of a moving object. Which technician is correct?
b
Bulbs with no indexing pins are often referred to as what?
bayonet bulbs
Technician A says that a capacitor contains a positive plate and a negative plate. Technician B says capacitors operate on the principle that opposite charges attract. Which technician is correct?
both
in an ignition module, noise is typically a raspy sound that varies with engine speed. How would you eliminate the noise?
by installing the capacitor on the positive side of an ignition coil
a combination of a Schmitt trigger and a Hall-effect device can be used as a _______________ _____________ in a distributor.
camshaft sensor
what are fixed resistors made out of>?
carbon or oxidized metal
A positive temperature coefficient, or PTC will _________________ its ______________ as temperature ______________
increase, resistance, rises
what sensor is also known as AC signal generator and also produces an alternating current ?
inductive/variable reluctance sensor
The rheostat is used to control the brightness of the __________.
instrument lighting
what is the purpose of a potentiometer ?
is to sense the position of a moving object
What needs to happen to an analog signal in order for it to have an impact?
it needs to be converted to a digital signal
what does the size of a fixed resistor indicate? And what is this called?
it relates to the amount of heat it can dissipate without becoming damaged. this is known as the power rating. typically larger the resistor higher the wattage
a capacitor can only store a certain amount of electrons without discharging. what is a capacitors rating equal to?
its equal to the capacitance which is the capacitors ability to store charge
What are the three types of piezoresistive pressure sensors ?
manifold air pressure or MAP sensors, brake pressure sensors or transducers, and engine knock sensors.
Camshaft sensors and crankshaft sensors are examples of ________________ ___________ ____________? is contact position sensors, optical sensors, or non contact position sensors?
non contact position sensors
often referred to as a pot
potentiometer
three terminal resistor, and controlled manually
potentiometer
the ___________ __________ of rheostat resistors has a long length of conductive wire twisted into a tight spiral formed into a circle
rotary type
the amount of resistance for a variable resistor is increased or decreased by ?
rotating the position of the wiper on the resistor
where would you find a what type of capacitor you're working with?
schematics
what do the terminals allow on a potentiometers internal resistor and moveable arm to send?
send varying voltage to the control module
What are the two main type of bulbs used?
single filament and double filament
think about a fan and the low vs high intensity setting it has. when its running at a low speed all the resistors are on when its at a high speed there's only one resistor or something. what type of resistor is this?
stepped resistor
which resistor can change position of the switch and change the current flow to the motor varying the speed?
stepped resistor
which resistor has at least two fixed resistor values?
stepped resistor
which resistor typically controls electrical motor speeds?
stepped resistor
Hall-effect sensors produce a digital signal. T/F?
t
The processor uses a PWM sensor to control ON time of a circuit. T/F?
t
With a high fuel level, the fuel sending unit will provide a low resistance.
t
With a low fuel level, the fuel sending unit will provide a high resistance.
t
on a resistor, the ____________ completes the circuit from the power source at the fixed end through the resistance wire to the ground side
terminal
When the temperature of the engine coolant reaches a certain heat what turns the fan on to cool it back down after the analog signal is triggered by the temperature increase?
the ECM
what does the term wattage refer to?
the amount of work being done in an electrical circuit.
on a resistor with four color bands, what do the four bands signify?
the first two bands are the digit bands, the third band is the multiplier, and the fourth band is the tolerance.
A common place to find a potentiometer would be the what ?
the fuel tank level sensor
the higher the watt of a bulb the more what?
the more electricity it uses thus creating more light and thus again creating more heat
How would a speed sensor help indicate a problem with traction in one wheel during slippage when driving?
the non drive wheel analog speed sensors would indicate a lower frequency or speed, while the wheel is losing traction and indicate a higher frequency because the wheel is moving faster than the others
on a potentiometer which terminal would be connected to the wiper contact?
the third terminal
in a computer circuit, too many amps to the circuit board causes what?
thermal damage
whats important to know about measuring bulbs in lumens?
they are measured at the object that is not lit, not at the source of the light
What component act as a potentiometer (a three wire mechanically operated variable resistor, based on a moving pole. The variable resistor changes the sensor's internal resistance as the position of the throttle changes. This resistance change sends a varying analog voltage signal dependant on throttle position, back to the ECM
throttle position sensor
The manufacturer's specification for the maximum resistance over and under the resistor's total resistance value is referred to as what?
tolerance
What does the equation on a four- and five-band resistor result in?
total resistance
which type of circuit would a double filament bulb service?
turn signal circuit
How does a piezoresistive sensor work?
when used as a knock sensor, the piezoresistive sensor detects vibrations in the engine. This information is relayed to the ECM, which adjusts the engine ignition timing to prevent detonation
fixed resistors with a power rating or wattage rating higher than 2 watts are normally what?
wire wound resistors
data link has to be within what from the driver seat?
18 in
Analog signals can change over a given range. they can change in frequency and voltage. What's an example of this?
A wheel speed sensor would show a low frequency signal when the car is moving at a low speed. As the vehicle's speed increases, the signal's frequency increases as well.
What type of signal is a continuous electrical signal that varies in amplitude or frequency and responds to changes in sound, light, heat, position or pressure?
Analog
How does a throttle position sensor work?
Because it is a potentiometer it is a three wire mechanically operated variable resistor which is based on a moving pole. The variable resistor changes the sensor's internal resistance as the position of the throttle changes. This resistance change sends a varying analog voltage signal, dependent on throttle position, back to the ECM
Resistors are also called a what?
a load device
What controls current flow through the instrument lights?
the variable resistor
What is a throttle position sensor considered?
a potentiometer
The multiplier band tells you what about a resistor?
number of zeros after the digits
a potentiometer has how many terminals?
three
a rheostat has how many terminals?
two
if you see a square wave pattern on your sensor. like when your looking inside of the sensor and it shows you a wave pattern and its square. what does that represent?
a digital signal.
on a wiring diagram your output is what?
a load or an actuator. "something that's doing work"
Lets say you have three sensors, a intake air temp sensor, engine coolant temperature sensor, and a transmission fluid temperature sensor. these sensors on the wiring schematic diagram your looking at has a line crossed through it on each sensor, what does that represent? and what does that mean?
a thermistor and it means that the resistance of the sensor will change based on temperature.
what does a circle around a little triangle or diode with two wires pointing out of it represent? it also has a MIL written next to it
an LED, a light emitting diode. malfunction indicator lamp (or check engine light)
what is a DLC
data link connector
automobile control modules can only read what type of signal?
digital
what is a DSO and what does it do?
digital storage oscilloscope. testing electrical shit
which type of circuit would a single filament bulb service?
dome light circuit
An active sensor produces its own voltage signal externally, generally above five volts. T/F?
f
Hall-effect sensors provide an analog signal. T/F?
f
Resistance change will occur in the sending unit when the fuel level is steady.
f
With a low fuel level, the fuel sending unit will provide a low resistance.
f
the size of the resistor determines the resistance value t or f?
f
On a rheostat, the first terminal is connected to a __________.
fixed contact
which resistor is made of carbon or oxidized metal?
fixed resistors
what is a benefit of bidirectional control with scan tools?
for example you can go into your scan tool and turn the fan on by itself and turn it off to see if its working properly
signal return wire on a sensor is a what wire?
ground wire
the instrument panel dimmer is activated when the __________ _________ delivers power to it
headlamp switch
frequency is measured in ?
hertz
2nd number of a trouble code means?
if its a 0 its not a problem specific to the manufacturer if its a 1 it is a manufacturer specific problem
You have a dashed figure eight on a wire schematic diagram. The example is on a vehicle speed sensor. what does the dashed figure eight represent?
indicates twisted wires. the magnetic field of each wire cancels out or minimizes interference.
what does the breakout box once in series help accomplish?
it gives you a test point for every sing wire that goes to the PCM
what is pulse width?
its the amount of time a signal is on
first letter of a trouble code means?
location of where the problem is
the third digit or your hundred codes. the number before the last two digits means?
narrows down further the location of the problem
do capacitors pass on electrons?
no
on a wire diagram anything that is labeled as an input is a what?
sensor
if you see two dashed circles kind of looking like a case your looking at what (on wire schematic)
shielding for something
dots on your wiring diagram represents what?
splice
your signal wire is giving information to your module so it can make decisions. what do you not want to do to that wire?
splice
what is the difference between a static test and a dynamic test?
static is when your circuit is open and your testing a section of your circuit. when you close the circuit and the circuit is live and then you test. thats a dynamic test
Adding fuel changes the float level.
t
Changing fuel levels causes the wiper arm to move across the fuel card.
t
what do you need to watch out with your coolant? and what do you need to make sure before you test it?
that it doesn't hold a bunch of voltage. rare, but still happens. make sure your coolant is cool
How do you recognize your signal wire on a sensor on a wiring schematic ?
there will be no splice, and its going to the PCM
the last two digits of the trouble code means?
this gives you a more specific location like a specific cylinder of something
sensors come in two categories what are they?
three wire or two wire
why is the green wire for DMM shielded?
to keep DMI or RFI disturbance from disrupting accurate results
sensor wires each have a purpose and name what is the difference between two wire and three wire ?
two wire has a signal and signal return. for three wire you have signal, signal return, power.
A potentiometer is an example of a _____________ sensor.... is it "fixed position" "variable position" or "variable reluctance"?
variable position
what type of resistors provide for an infinite number of resistance values within a set range?
variable resistors
what is a dynamic resistance test the same thing as ?
volt drop test
what wires can you splice on your sensor?
you can splice your signal return wire and your power wire.
what type of wire is never going to be spliced? is this wire typically power side or ground side?
your control wire, which by the way is typically ground side
