2. Computers can be called
CPU central processing unit
controls all electronic system
ECM engine control module
controls engine systems
PCM powertrain control module
controls engine & transmission only
TCM transmission control module
controls transmission & traction
BCM body control module
controls body systems
Generally for our learning purposes,
we’ll group them all as one
3. Computer Functions
• Input
– Is a signal sent from an input device.
• Processing (logic)
– The computer compares input information to programmed instructions.
• Storage
– The programmed instructions are stored in the computer’s memory.
• Output
– Is a command given by the computer to operate an output device.
4. Let’s at INPUTS first
• All inputs have same basic function
detect a mechanical condition, position, chemical state
temperature, or electrical value
change it into an electrical signal to be used by a computer.
6. Switches
something turned on or off
either by a person, or a device
switches are either normally open or
normally closed
they send an digital input signal
to the pcm
some switches switch the ground side
some switch the power side
if they switch power, it can be B+
or Reference Voltage
7. Switches
PSP Power Steering Pressure Switch
OD Overdrive Switch
CP Clutch Pedal Position Switch
IGN Ignition Switch
8. PNP Park Neutral Switch
BLS Brake Light Switch
ACC A/C Clutch Switch
TS Temperature Switch
9. Sensors
provide feedback information
(instead of on / off)
• Each sensor has a specific job.
✓confirms position or action
✓reports voltage changes
• All sensors are either
reference voltage sensors or
voltage generating sensors.
10. Various Sensors
CTS Coolant Temperature Sensor
ATS Air Temperature Sensor
TPS Throttle Position Sensor
ISC Idle Speed Control Sensor
CRK Crankshaft Position Sensor
11. CAM Camshaft Position Sensor
MAP Manifold Absolute Pressure Sensor
KNOCK Sensor
E G R Position Sensor
MAF Mass Air Flow Sensor
13. Remember this statement ?
• All sensors are either
reference voltage sensors or
voltage generating sensors.
Notice..... they all have to do with
voltage
They must either create their own voltage
or respond to the battery voltage
14. Let’s Talk About
Reference Voltage Sensors
“use of a source of information in
Reference means
order to ascertain something”
What are we
“referencing . . . . and why ?
15. Remember
this is
“Reference Voltage”
All we have to work with is the vehicles voltage
A good battery supplies 12.6 volts
A weak battery will supply less
16. A good charging alternator
can supply 13.5 - 14.5 volts
A bad alternator can supply
voltage above 14.5 volts
or no volts at all
leaving you with
battery voltage that is
decreasing
17. Since we are “measuring”
or “referencing” something
there must be a point where that measurement
is always the same
A car simply won’t run
if the voltage drops below
6 Volts
18. So............
to solve this problem
The computer sends a constant
5 volts
to the sensor
That way it can’t be confused with any voltage
generated by something other than
what the computer sends out
19. And it provides a constant point
to measure from
“reference”
5 For all of the sensors
volts that need to measure
or “reference” voltage
20. Reference Voltage Sensors
• Computer sends a constant voltage to the sensor.
• The sensor reacts and sends a voltage signal back to t
• Reference voltage is normally 5 to 9 volts.
• Most are variable resistors or potentiometers.
21.
22. So......... inputs can be
Switches On or Off
5
Reference voltage feedback sensors volts
OR
Voltage Generating Sensors
they make their own voltage signal
23. Voltage Generating Sensors
• Produce an input voltage for the control system
• Speed sensors
• Knock sensors
• Hall-effect switches
• Oxygen sensors
24. How do they produce voltage ? ?
• Use magnetic induction.
Magnetic Pulse Generators
• Also called permanent magnet generators.
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QuickTime™ and a
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31. What is a solenoid ?
A coil of wire, wound tightly
around a metallic core,
which produces a magnetic field
when an electric current is passed through it.
They can create a controlled magnetic field
and can be used as electromagnets
32. QuickTime™ and a
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Simplified Control
Being a pulsed device with minimal components optimizes
solenoids for digital control. This results in faster cycling and
higher reliability with fewer interfaces.
Uncompromising Reliability
Solenoids provide repeatable, predictable performance
with a specified life of up to 100 million cycles.
33. QuickTime™ and a
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QuickTime™ and a
Animation decompressor
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34. Starter solenoid Throttle solenoid
Variable Valve solenoid
Trans shift solenoid Fuel injector solenoid
Idle air control solenoid
Fuel Solenoid EGR solenoid
Door lock solenoid
36. Relays are remote control electrical switches
that are controlled by another switch
Horn Circuit
Switch #2
A switch
controlled by
A switch
Switch #1 Horn
Switch
37. QuickTime™ and a
GIF decompressor
are needed to see this picture.
40. An electric motor is an electromechanical device
that converts
electrical energy into mechanical energy
QuickTime™ and a
QuickTime™ and a
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