Advanced Electrical Theory
Advanced Electrical Theory
Advanced Electrical Theory
Reference
Booklet
Advanced Electrical
Theory & Diagnosis
Module 602
© Copyright 2001
Subaru of America, Inc.
All rights reserved. This book may not be reproduced
in whole or in part without the express permission of
Subaru of America, Inc.
Table of Contents
Slide Sequence ................................................................................................4
Slide Sequence ................................................................................................5
Introduction ............................................................................................................6
Solid State Devices ...............................................................................................6
Testing Transistors ........................................................................................ 12
Alternators .......................................................................................................... 13
Solid State Voltage Regulator ....................................................................... 14
Alternator Testing Precautions ...................................................................... 14
Starters ............................................................................................................... 15
Starter Types ................................................................................................. 15
Operation ............................................................................................................ 15
Starter/Solenoid Testing Procedures ............................................................ 16
Opcilloscope Testeing and Diagnosis............................................................... 17
Computer Terminology and Operation .............................................................. 18
Computer Hardware ...................................................................................... 18
Computer Software ........................................................................................ 18
Terminology ................................................................................................... 18
Troubleshootingn Diagnosis of Intermittent Faults ........................................... 19
Intermittent Faults ............................................................................................... 20
Thermal and Mechanical ............................................................................... 20
Select Monitor Usage ......................................................................................... 20
Electrical Symbols .............................................................................................. 22
Electrical Terms Glossary .................................................................................. 23
Alternating Current (AC) ................................................................................ 23
Direct Current (DC) ........................................................................................ 23
Sine Wave...................................................................................................... 23
Square Wave ................................................................................................. 23
Resistance ..................................................................................................... 23
Dynamic Resistance ..................................................................................... 23
Voltage Drop .................................................................................................. 23
Resistor .......................................................................................................... 23
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Slide Sequence
Slide No. Description page No.
1 Title Slide (Advanced Electrical)
2 Created By
3 Teaching Aids
4 Introduction 6
5 Title Slide (Solid State Devices) 6
6 Semi-Conductor 7
7 Lattice Structure 7
8 Electron Current Flow 7
9 Diagram of Diode 8
10 Diode Symbols 8
11 Testing Diode 9
12 AC Sine Wave 10
13 Three Phase Sine Wave 10
14 LED/PSD 10
15 Zener Diode Operation 11
16 PNP Transistor Construction 11
17 NPN Transistor Construction 11
18 Title Slide (Testing Transistors) 12
19 PNP Transistor Testing 19
20 Title Slide ( Alternators) 13
21 Alternator Components 13
22 Component Operation 13
23 Stator Construction 13
24 Capacitor Operation 14
25 Title Slide (Starters) 15
26 Starter Types 15
27 Magnetic Switch / Solenoid 15
29 Starter Drive Operation 15
30 Title Slide (Operation) 15
31 Magnetic Switch / Solenoid 16
32 Title Slide (Oscilloscope Interpretation & Diagnostics) 17
33 Oscilloscope CRT 17
34 NSM (Main Menu 1) 17
35 NSM (Main Menu 4) 17
36 NSM 17
37 NSM 17
38 Lab Area
39 Title Slide (Computer Terminology an Operation) 18
40 Hardware 18
41 Software 18
42 Terminology 18
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Slide Sequence
Slide No. Description page No.
43 Networking 19
44 CPU Operation 19
45 Title Slide (Troubleshooting Diagnosis of Intermittent Faults) 19
46 Six Step Troubleshooting 19
47 Intermittent Faults 20
48 Select Monitor 20
49 Lab Area
50 Copyright 2001
51 The End
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Introduction shaped wave that alternately assumes a "ON"
or "OFF" mode. The length of the "ON" time
This Technicians Reference Booklet contains
compared to the "OFF" time indicates a "duty
information pertaining to advanced automotive
ratio".
electrical technology, and the Subaru electrical
system. It reviews solid state devices, operation This booklet contains a Glossary of electrical
and diagnosis of Subaru starting and charging terms for your reference. Refer to the Glossary
systems, operation and diagnosis, computer when appropriate throughout the duration of this
terminology and operation, and the module.
troubleshooting and diagnosis of intermittent
faults. In addition, the use of the Select Monitor
is also explained during the presentation of the
module and will be demonstrated during the lab
exercises.
6
7
Diodes
Lattice structure
We begin our study of advanced electrical theory
with an explanation of the construction and
operation of diodes.
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Negative charges are attracted to positive Exceeding the amperage rating of the diode may:
charges at the barrier junction, when the proper
polarity voltage is applied. When the negative and • Fuse the P/N junction, creating a short
positive charged atoms meet at the barrier circuit. The diode will then act like a solid
junction, the electrons will then move in a chain wire conductor, or
reaction toward the positive terminal of the diode. • Open the P/N junction creating an open
This is equal to current flow through the diode. circuit through which no current may flow.
9
Diode polarity
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2. Voltmeter test
• The diode must in an operating circuit.
Connect the voltmeter leads to the diode
leads, (observe polarity). Refer to the
appropriate wiring diagram to determine
the voltage that should be in the circuit. In
most automotive applications this will be
11 B+ voltage. The diode is "OK" when the
Testing diodes meter readout is as follows:
- Silicon diode — approx. 0.7 voltage
You may use an ohmmeter of a voltmeter to test drop (dynamic resistance)
the operation of a diode. - Germanium diode — Approx. 0.2
voltage drop (dynamic resistance)
1. Ohmmeter test
• Connect the meter positive lead to the The voltage drop reading always identifies the
cathode (-) lead of the diode and the meter diode type. Any other reading indicates a circuit
negative lead to the anode (+) lead of the or diode defect, and further testing will by
diode. The result should be high required.
resistance meter reading, ex: 5k ohms or
more. This is due to the "unlike" charges If the meter readout voltage is equal to the circuit
of the voltage source (ohmmeter) and the voltage, the diode is open (all current is flowing
diode material. The electrons and "holes" through the voltmeter). When the meter readout
are pulled to the outside ends of the diode voltage is equal to 0.0 volts, the diode is fused
causing a large depletion region at the P/ (shorted). All the current is flowing through the
N junction. A low resistance reading diode.
would indicate that the diode is "shorted",
and requires replacement. NOTE: A DIODE'S PERFORMANCE DOES
• If you now reverse the meter lead NOT DETERIORATE WITH TIME OR USE.
connections, the result should be a low THEREFORE, WHEN TESTING, THE RESULT
resistance reading, ex 100 ohms or less. WILL EITHER BE "GOOD" OR "BAD",
This is due to the "like" charges of the HOWEVER, IT IS POSSIBLE FOR A DIODE TO
voltage source (ohmmeter) and the diode BE INTERMITTENTLY "GOOD" OR "BAD".
material. The electrons and "holes" are
repelled (pushed) to the P/N junction
which allows current to flow. A high
resistance reading indicates that the diode
is "open", and must be replaced.
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14
12 LED/PSD
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While a diode is formed by the joining of two
specially doped materials, a transistor is formed
by the joining of three doped materials.
• Emitter material emits current
• Collector material collects current.
• Base material supplies the path used to
initiate or control current flow.
The zener diode allows reverse bias (voltage) Operational control of a transistor is determined
at a predetermined level based on the impurity by the polarity of the base material which
added to the adhesive between the P and N determines the polarity of the voltage supplied
materials. This places the P.I.V. rating of the to the base. Thus, a PNP transistor operates by
zener diode at a required specific value, i.e., 14 flooding the base material with free electrons
volts. Remember that silicon diodes may gave a (negative polarity). This allows the transistor to
P.I.V. of a 1000 volts. This allows the zener diode act as a switching relay, initiating current flow
to modify current flow by switching the circuit from the emitter to the collector. One of many
rapidly :ON" and "OFF" when the applied applications of a PNP transistor is in the
voltage increases or decreases. The zener diode electronic ignition system.
is used in voltage regulators to prevent
overcharging or undercharging of the battery.
17
NPN transistor
16
Construction and operation of the NPN transistor
PNP transistor is similar to the PNP transistor. In this case
however, the base material is flooded with holes
A transistor is a solid state device used to control (positive polarity) to control current flow from the
current flow. Two of many types of transistors emitter to the collector. The NPN transistor is
which may be identified by their polarity/lead often used as an amplifier in audio systems and
designation are: other solid state circuits. This is the transistor
• PNP = positive/negative/positive which has allowed the miniaturization of
• NPN = negative/positive/negative electrical circuits by eliminating bulky vacuum
tube circuitry.
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Testing Transistors 5. The result should be a HIGH resistance
reading
• Example: 5 K ohms or more
You may use an ohmmeter to test the operation NOTE: REVIEW THE TRANSISTOR LEAD
of a transistor. IDENTIFICATION CHART SHOWN IN THIS
1. Always use the diode testing scale of an TRB.
ohmmeter to test a transistor.
2. Test the transistor an two diodes. A voltmeter test of transistor operation is not
• First test the emitter to base (E-B) practical in most automotive applications.
• Then test the collector to base (C-B)
NOTE: A TRANSISTOR'S PERFORMANCE
3. The result will be "good" or "bad". Meter DOES NOT DETERIORATE WITH TIME OR
readings will vary depending on transistor USE.
type.
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Alternators
23
21 Stator contruction
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When full-fielding the alternator, never exceed
16.0 volts. Voltage levels in excess of this
specification may cause damage to electrical
system components.
Never disconnect the battery during an alternator
test.
Never lay tools on the battery. Listed in the appropriate MY Subaru Service
Subaru Starting Systems.
Always disconnect the battery prior to alternator
replacement.
Secure loose harness/wiring to prevent damage
caused during alternator removal/replacement.
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Starters The components of the magnetic switch/solenoid
are:
Starter Types
• Pull-in winding
• Reduction Gear
• Hold-in winding
• Direct Drive
• Plunger
• Return spring
• Shift lever
• Starter motor contacts
27
Starter components
29
The components of the starter assembly are:
• Pinion (drive)/one-way clutch Operation
• Armature
• Commutator When the ignition switch is turned to the
• Field shoes "START" position, battery voltage (B+) is allowed
• Brushes/brush holders to energize the magnetic switch/solenoid pull-in
• End caps/bushings and hold-on coils. The field created by the coils
moves the plunger which in turn moves the shift
lever engaging the starter pinion with the
flywheel. The movement of the plunger also
activates the starter motor switch contacts. This
allows B+ voltage from the battery cable to flow
to the starter motor through the magnetic switch.
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An occasional problem with starting systems is Starter/Solenoid Testing Procedures
a defective hold-in winding in the solenoid. In
this situation, the solenoid will "click" rapidly. This
occurs because the pull-in winding moves the
plunger but the hold-in winding is not energized.
Since no hold-in field is created and the pull-in
winding field is released as the start switch is
engages, the plunger return spring returns the
plunger to the pre-start position. This process
repeats and the plunger moves back and forth
rapidly. This action will momentarily engage the
flywheel, and occasionally may rotate the
flywheel enough to start the engine. 31
Magnetic switch/solenoid
NOTE: THESE SYMPTOMS ARE SIMILAR TO
THOSE CAUSED BY A DEFECTIVE Use an ohmmeter to test the pull-in and hold-in
BATTERY OR BATTERY CONNECTIONS. windings. Always refer to the appropriate MY
THEREFORE, A BATTERY PERFORMANCE Subaru Service Manual, Section 6-1.
TEST, AND AN INSPECTION OF THE
BATTERY CONNECTIONS MUST ALWAYS Use a voltmeter to conduct a starter motor test
BE PERFORMED PRIOR TO for intermittent operation. Complete the following
TROUBLESHOOTING THE STARTER steps:
SYSTEM. 1. Connect the voltmeter leads to the starter
motor terminal and to a ground.
2. By-pass the solenoid by connecting a jumper
cable from the solenoid B+ terminal to the
solenoid starter motor terminal. This spins the
starter, but dies not engage the magnetic
switch/solenoid.
3. If there is a steady voltage reading the starter
motor components are OH.
• Brushes
• Commutator
• Armature
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Opcilloscope Testeing and
Diagnosis
33
Oacilloscope CRT 36
Oscilliscope usage during diagnostics can help This will give you one or two channel operation.
with finding intermittent or unusual problem
conditions
37
35
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Computer Terminology and
Operation
Computer Hardware
Automotive computer hardware is the electronic
and tangible componentry used for its operation.
a. The CPU (central processing unit) is the area
in which all arithmetic and logic decisions are
calculated/computed.
b. The address register is similar to a file cabinet.
It is where the computer sets up unique file
locations to store data in the memory. 42
c. The data register is used by the CPU to "read"
and "write" information to/from the memory Terminology
files. BIT (binary digit) This is the smallest unit of
d. The ROM (read only memory) contains information in the binary system used by the
information that is programed into the computer. The computer uses binary numbers
computer during the manufacture of the to build letters, numbers, and other characters
computer. These operating commands used to record and display information.
cannot be changed or updated.
e. RAM (random access memory) is where The only binary numbers generated and used
information is continually updated by the by the computer are either zero ("0") or one ("1").
inputs from the various engine sensors. The Zero equals power "OFF", and one equals power
RAM is often called the "scratch pad" of the "ON". Switching the power "ON" and "OFF" to
computer. specific circuits in the computer, codes the
information that is entered or displayed. It
Computer Software requires 8 BITS or 8 binary digits to equal 1
The software consists of the programs and data BYTE.
used by the computer to perform specific tasks.
a. The PROM (programmable read only BYTE (binary element string)
memory) is information programed into the
computer "chip". It contains the operating A BYTE is equal to 1 character, such as the letter
characteristics of a specific model or engine "a". Therefore a BYTE contains a combination
family and can be added to the computer of eight "1's" or "0's" (BITS).
during vehicle assembly to "fine-tune" vehicle Example: 1 0 0 1 1 0 1 0
operation.
b. The EPROM (erasable programmable read "K" = 1000 or kilo (as in metrics). This term is
only memory) is similar to the PROM in used to indicate toe amount of memory space
operation. Information can be: available in a computer. If it has 32K BYTES,
• Erased under ultra-violet light. then it can store 32,000 characters in its memory.
• Reprogrammed to a new set of values.
Mega hertz (Mhz) This term defines the
processing speed of the computer in millions of
cycles per second.
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When the data in the CPU register matches the
data in the RAM, no action is required. If the data
in the CPU register does not match the data in
the RAM, the CPU generates a command signal
to the appropriate device to alter vehicle or
specific component operation.
This term refers to the exchange of If the data received is illogical to or from the
predetermined information that establishes a computer, the computer generates a fault code.
connection between two or more computers.
Without handshaking one computer would not All information, both to and from the CPU is
be able to understand another computer's data resented almost simultaneously. However, it is
input and vice-versa. The ROM's initiate the synchronized by an internal clock. The clock also
connection while the RAM sections exchange controls the overall processing speed of the
information. This process is also called computer. Speed is measured in mega hertz
networking.
(Mhz), which equal millions of cycles per second.
During networking the clock pulse will determine
which computer is sending and which computer
is receiving.
Troubleshootingn Diagnosis of
Intermittent Faults
Six Step Troubleshooting
Step 1 — Verify the problem(s)
Step 2 — Determine related symptom(s)
Step 3 — Isolate the problem
44 Step 4 — Identify the cause
Computer operation Step 5 — Repair/replace
Step 6 — Verify operation 46
The CPU sends an information request to the
ROM (memory) over the address buss line NOTE: REFER TO THE SUBARU BASIC
(connecting wires) to the address register. The ELECTRICAL THEORY & DIAGNOSIS
CPU then temporarily stores this information in MODULE, STEP 10 FOR ADDITIONAL
the CPU register while it compares the INFORMATION CONCERNING THE SIX STEP
information to data stored in the RAM. The RAM METHOD.
data is the inputs received by the computer from
the various vehicle sensors.
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Intermittent Faults NOTE: DO NOT UNDER ANY SITUATION
BYPASS A FUSE OR CIRCUIT BREAKER.
Thermal and Mechanical SEVERE DAMAGE TO THE VEHICLE AND
1. Thermal intermittent POSSIBLE PERSONAL INJURY MAY
• This type of problem occurs most often in OCCUR.
solid state devices, connectors, switches,
etc. Usually as the operating temperature
Select Monitor Usage
of a component increases, it causes an
expansion of the material which causes
the circuit to "OPEN". Current flow stops,
the material cools and contracts, and
restores circuit operation.
2. Mechanical intermittent
• This is caused by a component or
connection bending or shifting during
normal vehicle operation.
• You may sometimes solve intermittent 48
problems using the following strategies:
Select monitor
- Use a hair dryer to heat a component
or connection to simulate a severe The select monitor allows a review of the actual
operating failure condition which you information processed by the computer. For
believe to be heat related. instance, thermosensor input is displayed as the
- Mist water on a malfunctioning actual temperature of the coolant. You can then
component to determine if heat is
compare the select monitor coolant temperature
causing the problem. This simulates
reading with the actual coolant temperature to
a cooler operating temperature.
determine possible sensor problems. (With a cold
NOTE: DO NOT MIST COMPONENTS THAT engine, the coolant temperature should be equal
CANNOT TOLERATE MOISTURE. MAY to the ambient air temperature).
CAUSE DAMAGE TO THE COMPONENTS.
Likewise, computer outputs may also be
- Use a component cooler which will checked: The select monitor will display the
quickly cool solid state components computer output to a system component such as
without damage to the components. the fuel injector. This signal (injection pulse width)
This method will identify intermittent is displayed in milliseconds. We know that
diode or transistor problems thermosensor input will effect injection pulse
because the component will usually width. With increased coolant temperature,
malfunction when cooled quickly. injection pulse time (duration) should be reduced
and the fuel mixture should become leaner. With
NOTE: DO NOT USE FREON WHICH
decreased coolant temperature, injection pulse
CAUSES DAMAGE TO THE ENVIRONMENT!
time should increase and the fuel mixture should
- Jumper leads may be used to become richer. No change in the select monitor
bypass connectors, switches, and injector signal could indicate thermosensor circuit
cables to check an intermittent problems.
problem.
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NOTE: REFER TO SELECT MONITOR
INTROCUCTION VIDEO REFERENCE
BOOKLET MSA5AV148B AND THE
APPROPRIATE MODEL YEAR SERVICE
MANUALS FOR DETAILED SELECT
MONITOR INFORMATION.
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Electrical Symbols
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Electrical Terms Glossary
Potentiometer
Alternating Current (AC) A resistive element with a sliding wiper contact
an electric current which constantly changes that is used in applications in which a division
polarity from positive to negative, (or an electric of resistance is required (such as a three-
current that reverses its direction regularly and terminal adjustable resistive divider). Example:
continually). The throttle sensor on SPFI and MPFI fuel
systems.
Direct Current (DC)
an electric current which flows in one direction Splice
only. Joining of two or more conductors at a single
point.
Sine Wave
a wave that alternately moves between a Terminal
positive and a negative value over an equal Device attached to the end of a wire or cable to
length of time make an electrical connection.
Square Wave Ground/Chassis ground
a square or rectangular-shaped wave that Negative side of a complete circuit. In
alternately assumes a "ON" or "OFF" mode. automotive applications the negative side of
The length of the "ON" time compared to the the battery or any wire connected to the
"OFF" time indicates a "duty ratio". engine, frame, or body sheet metal.
Resistance Relay
Property of an electrical circuit that tends to Electromagnetic switching device using low
prevent or reduce the flow of current. current to open or close a high-current device.
Dynamic Resistance Solenoid
Effect of a resistor or resistance in a circuit. an electromagnetic device consisting of a
tubular soil of wire containing a core that
Voltage Drop moves when the coil is energized. Movement
The difference in voltage between one point in of the core can open/close a circuit. A solenoid
a circuit and another, or the difference in converts electrical energy to mechanical
measured voltage from one side of a energy.
component to the other side.
Filament
Resistor A fine high resistance wire or thread which
Device that permits a predetermined current to glows and produces light when current is
flow aat a given voltage. Examples are a SPFI forced through it.
ballast resistor and a 4EAT dropping resistor.
Diode
Rheostat solid-state device that permits current to flow in
See Variable resistor. one direction only; performs like a one-way
check valve.
Variable Resistor/Rheostat
a device that adjusts the amount of resistance Transistor
required. An example is a sliding contact Solid-state semiconductor that is a
resistor. The position of the contact determines combination current amplifier and switch
the amount of resistance. The fuel sending (similar to a solenoid in the starter circuit or a
units of a vehicle equipped with an analog relay in function). It uses low control current to
dash use a variable resistor. channel high current.
Capacitor (Condenser)
Device used to store an electrical charge.
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Notes:
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