sensors diodes transistors...
TRANSCRIPT
![Page 1: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/1.jpg)
Common SensorsUnderstand the following sensors:
Pull Up sensorPull Down sensor
PotentiometerThermistor
![Page 2: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/2.jpg)
Pull Up Switch (sensor)VERY low current
12 volt
![Page 3: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/3.jpg)
Pull Up Switch (sensor)VERY low current
12 volt
12 volt
![Page 4: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/4.jpg)
Pull Down Switch (sensor)VERY low current
![Page 5: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/5.jpg)
Pull Down Switch (sensor)VERY low current
![Page 6: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/6.jpg)
Test the Switch - Sensor
Check Scan tool PID data for sensor
Should show ON/OFF or Open/Closedas you operate the switchIF No change, check voltage at switchLook for open /shorted wires (use voltmeter and logic to see if wire is open or shorted)
![Page 7: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/7.jpg)
Potentiometers
A potentiometer is a Position sensor
![Page 8: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/8.jpg)
4 volt
PotentiometerVery low current
![Page 9: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/9.jpg)
2 volt
PotentiometerUsed as a sensor
![Page 10: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/10.jpg)
2.5 volt(should be 2 volt)
Potentiometerpoor ground
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5 volt(should be 2 volt)
Potentiometeropen ground
![Page 12: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/12.jpg)
Potentiometers sense motion
check for: reference voltagegood groundun-interrupted signal
![Page 13: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/13.jpg)
0.52 V MIL lamp lit. TPS code
What is wrong?
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0.0 V MIL lamp lit. TPS code
What is wrong?
![Page 15: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/15.jpg)
Thermistors
Thermistors change resistance with temperature
Negative Temperature Coefficient thermistors decrease in resistance when they heat
Commonly used to sense changing temperatures
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High Resistance when Cold!
![Page 17: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/17.jpg)
Low Resistance when Hot!
![Page 18: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/18.jpg)
4.52 VHot or Cold?COLD!
![Page 19: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/19.jpg)
1.53 VHot or Cold?HOT!
![Page 20: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/20.jpg)
1.45 V1.15 V
Poor gas mileage, runs rich, may set oxygen sensor code
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Poor gas mileage, runs rich, may set oxygen sensor code
0.49 V
![Page 22: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/22.jpg)
Poor gas mileage, runs rich, may set oxygen sensor code
0.02 V
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Thermistors
Thermistors are checked with an Ohmmeter or a Voltmeter
A temperature probe or thermometer should be used when checking
Compare temperature at measures at sensor temperature displayed on Scan Tool
![Page 24: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/24.jpg)
Semiconductors
Elements with four valence electrons are not good as insulators or conductors
Silicon, when is a crystal form, shares valence electrons to make a good insulator
Silicon can be “doped” to add electrons to the valence ring or remove electrons from the valence ring
![Page 25: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/25.jpg)
Semiconductors
Silicon doped with phosphorous (which has five electrons in the valence ring) will create an “N” type semiconductor
Silicon doped with boron (which has three electrons in the valence ring) will create a “P” type semiconductor
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Semiconductors
All Semiconductors will be destroyed by:
Too much Current
Too much Voltage
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Diodes
Placing an “N” type semiconductor with a “P” type will create a diode.
In a forward biased diode current will flow with a small amount of resistance
Too much current will overheat and destroy the diode
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Diodes
Reverse biasing a diode will create very high resistance at the center of the diode and current will not flow
Too much voltage will overcome the internal resistance and the diode will short out
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12.6 V
Arrow shows conventional theory (hole flow)
Diodes wired like this will block current
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0.0 V
Arrow shows conventional theory (hole flow)
Diodes wired like this will block current
![Page 31: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/31.jpg)
Arrow shows conventional theory (hole flow) Diodes wired like this will allow current to
flow with a slight voltage drop
12.6 V
![Page 32: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/32.jpg)
Arrow shows conventional theory (hole flow) Diodes wired like this will allow current to
flow with a slight voltage drop
12.0 V
Diodes use (Drop) about .5 volts
![Page 33: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/33.jpg)
Arrow shows conventional theory (hole flow) Diodes wired like this will allow current to
flow with a slight voltage drop
0.1 V
![Page 34: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/34.jpg)
Testing Diodes
Diodes require .2 - .6 volts to forward bias
Digital ohmmeters may not supply this voltage with ohm check
use diode check feature when using DVOM
![Page 35: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/35.jpg)
Testing Diodes
Shorted diodes on alternators will allow A/C voltage that may confuse a control module
Routine checks with oscilloscope are easy
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Anti- Spike Diodes
Clamping or Anti-Spike diodes protect sensitive control modules from …..
….Too much VOLTAGE
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![Page 39: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/39.jpg)
![Page 40: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/40.jpg)
![Page 41: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/41.jpg)
Semiconductors
All Semiconductors will be destroyed by:
Too much Current
Too much Voltage
![Page 42: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/42.jpg)
Failure in Anti- Spike Diodes
An open, or shorted diode will damage computer control modules
Shorted relay coil windings will cause too much current to flow and burn out switching transistors in computers
Shorted Diodes allow too much current
Check resistance with an OHM meter
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Failure in Anti- Spike Diodes
An open, or shorted diode will damage computer control modules
Open diodes allow spike voltages to harm electronic components (too much VOLTAGE)
Oscilloscope will show an OPEN diode for any coil
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Types of Diodes
Positive diodeNegative diode
Zener Diode
Light Emitting Diode (LED)
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![Page 47: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/47.jpg)
Transistor acts like a very fast On/Off pull down switch
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Transistors
Transistors can act as a relaythey use a small signal current to control a larger working current
Transistors can act as a signal amplifier
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PNP transistor
Points In Permanently
Will conduct current when the base sees a Negative polarity
![Page 50: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/50.jpg)
![Page 51: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/51.jpg)
![Page 52: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/52.jpg)
NPN transistor
Never Points In
Base must be Positive to allow transistor to conduct current
![Page 53: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/53.jpg)
![Page 54: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/54.jpg)
![Page 55: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/55.jpg)
![Page 56: Sensors Diodes Transistors print.pptcf.linnbenton.edu/.../upload/Sensors_Diodes_Transistors_print.pdf · (use voltmeter and logic to see if wire is open or shorted) ... (LED) Transistor](https://reader031.vdocuments.mx/reader031/viewer/2022030511/5abbcaef7f8b9a8f058cdce9/html5/thumbnails/56.jpg)
Transistors can act as a Signal Amplifier
Small changes in current flow through the Base will result in large current flow changes through the Emitter and Collector
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TransistorsTransistors are damaged by too much current
check resistance of the LOAD (The load is what is being turned ON or OFF)
Transistors are damaged by high voltage
Coils turning OFF create high voltageCharging systems that allow Overcharging can damage control modules and computers
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Diagnose Control ModulesElectronic control modules can not be directly tested
Before replacing, verify proper operation of PowerGroundSensors (inputs)Actuators (outputs)
Remember… Electronics are damaged byhigh voltagehigh current
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Diagnose Control Modules