AURETR003 Learner Workbook

Electrical
Systems
This learner workbook AURETR003 Apply

supports the automotive automotive electrical
competency unit: system fundamentals

WHS/OHS Training
We recommend that learners complete the WHS/OHS unit AURASA2002 Apply safe working
practices in an automotive workplace before commencing this Study.
Safety Disclaimer
Auto Skills Australia does not accept any liability for injury or damage in relation to these Learning
Resources – ask Len
This publication has been produced with the assistance of

funding provided by the Commonwealth Government through
the Australian Government Department of Industry.

AURETR003 Apply automotive electrical system fundamentals Version: 1.0 / February 2014
©Auto Skills Australia Page 1 of 48

Table of Contents
INTRODUCTION 4
TOPIC 1 - INTRODUCTION TO ELECTRICAL SYSTEMS 6
TOPIC 2 - WORKPLACE HEALTH AND SAFETY 7
TOPIC 3 - ELECTRICAL PRINCIPLES 8
TOPIC 4 - WHS/OHS FOR ELECTRICAL PRACTICES 15
TOPIC 5 - ELECTRICAL CIRCUITS 20
TOPIC 6 - TESTS AND FAULTS 31
TOPIC 7 – IDENTIFY AND LOCATE ELECTRICAL SYSTEMS 39
TOPIC 8 – FIELD WORK 45
APPENDIX I - ANSWERS 47
APPENDIX 2 – CIRCUIT DIAGRAMS 48


Detailed Table of Contents
INTRODUCTION 4
TOPIC 1 - INTRODUCTION TO ELECTRICAL SYSTEMS 6
TOPIC 2 - WORKPLACE HEALTH AND SAFETY 7
2.1 Hazard Control 7
TOPIC 3 - ELECTRICAL PRINCIPLES 8
3.1 Electrify in Vehicles 8
3.2 Electricity and the Atom – Protons, Neutrons, Electrons 9
3.3 Electrical Current: Conventional vs Electron 10
3.4 Current, Voltage, Resistance and Ohm’s law 11
3.5 How do we measure the aspects of electricity? 12
3.6 Types of Electricity – Variations on a Theme 12
3.7 Learning Check for Electrical Principles (Respond Online) 14
TOPIC 4 - WHS/OHS FOR ELECTRICAL PRACTICES 15
4.1 Electrical Hazards - The Science of Electric Shock 15
4.2 Current Involved in Electric Shock 16
4.3 Shock Physiological Effects 16
4.4 Hazard management techniques 17
4.5 Learning Check for Electrical Safety (Respond Online) 18
4.6 Personal safety 19
TOPIC 5 - ELECTRICAL CIRCUITS 20
5.1 Components of a Circuit 20
5.2 Load 20
5.3 Ohms Law 21
5.4 Circuit Symbols 22
5.5 Voltage Drop 23
5.6 Parallel Circuits 25
5.7 Sample Wiring Diagram: Headlight Circuit 27
5.8 Circuit Faults 28
5.9 Electrical Power 29
TOPIC 6 - TESTS AND FAULTS 31
6.1 Testing Equipment 31
6.2 Multimeter 31
6.3 Multimeter Operation 32
6.4 Test Lamp 33
6.5 Battery Tester 33
6.6 Insulated hand tools 34
6.7 Computer interface – OBD Functions 35
6.8 Fault Finding Technique 36
6.9 Extra Information 36
6.10 Common Faults 38
TOPIC 7 – IDENTIFY AND LOCATE ELECTRICAL SYSTEMS 39
TOPIC 8 – FIELD WORK 45
APPENDIX I - ANSWERS 47
APPENDIX 2 – CIRCUIT DIAGRAMS 48


Introduction
Welcome to Electrical Systems based on competency unit AURETR003 Apply automotive electrical
system fundamentals.
Study Overview
This Study will contribute to your introduction to the automotive industry. You will learn the language
of automotive electrical practices and the principles on which automotive electrical technicians work.
You will learn about electrical systems and components – the battery, generator and starter motor, for
instance – and how all the parts interact in the modern automobile. You can use this Study to simply
build your understanding of the automotive industry or as a step towards a career as an automotive
electrical technician.
Purpose
To develop an entry-level knowledge and awareness of automotive electrical terms and principles as
they apply to the vehicle electrical systems, components and technologies found in modern motor
vehicles.
Content
In this Study you will learn about:
• Basic electrical principles

• The electrical systems and components that make up
an automobile
• The functions of these systems and components
• How to identify and locate systems and components on
a modern vehicle
• The faults common to automobile systems
• Sources of information to help you work with
automotive systems and components
You will apply this learning in several simple activities that will give you an insight into the automotive
industry.
Duration
The guideline for this Study is 20 hours. For this Study this means six two hour sessions and up to
three hours for revision and assessment. Your instructor may change this to suit your needs and past
experience.
Study Notes
These Study notes can be used as evidence for your assessment. Spaces have been left for you to
record your work as you progress. Please make every effort to complete the Study notes. It will
benefit you in the long run.
Assessment
When you undertake this Study you will be required to complete the following assessment tasks. If
you complete them successfully under the auspices of a registered training organisation (RTO) you
may be awarded a statement of attainment for the competency unit AURETR003 Apply automotive
electrical system fundamentals.
Assessment Tasks
The assessment tasks you will complete are:
1. Workbook activities 1 to 14


2. Twenty question online test
3. Three demonstration tasks which will include:
• locate at least three electrical systems and components on contemporary motor vehicles
• explain the function and operation of at least three electrical systems of a contemporary
passenger vehicle or light commercial vehicle
• demonstrate on at least three occasions basic fault finding techniques to determine possible
causes of electrical faults
The materials and supervision necessary to complete these tasks will be supplied by your training
provider or instructor.
Special Note - Mechanic Interview

As part of the activities for this Study you will interview an experienced motor mechanic or automotive
technician. The interview need not take more than 30 minutes. You may wish to contact a
mechanic/technician to arrange that interview once you have started the Study.
The interview requirements are set out in Topic 6.


Topic 1 - Introduction to Electrical Systems
If petrol-driven motor vehicles produce harmful gasses that will cause our climate to change – and a
lot of people in powerful positions think they do – then electricity, electronics and electrically-driven
cars are the way of the future. What does that mean? Look at these examples from the Internet.
http://www.aboutmyplanet.com/science-‐technology http://cleanfuelconnectionnews.com/electric-‐vehicles/ http://www.mnn.com/green-‐tech/transportation/

No thinkstock images
Will we all be driving solar powered cars that are only 600mm high? Will there be a recharge points
that collect and dispense solar energy? Will we all be compelled to take solar powered public
transport?
The answer is that in the long run we will develop technologies that include all these ideas and many
more – and we will be better off because of it.
And, what will happen to mechanics? Will they be out of work?
The answer is that mechanics will work more and more with electrical systems and the mechanics
new skills will make them even more important to the economy than they are now.
This Study is a foundation to all the skills you will need to work on motor vehicles in the future. We
look at the basic principles of electrical systems, how these are applied in cars and how a mechanic
can diagnose problems and solve them using this foundation knowledge.


Topic 2 - Workplace Health and Safety
The workplace health and safety (WHS or OHS) Study for competency unit AURASA2002 Apply
safe working practices in an automotive workplace covers all aspects of safety in an automotive
workshop. In this Study we take a more detailed look at WHS/OHS activities that relate to ‘electrical
systems’ – see Topic 2 WHS/OHS for Electrical Practices. In general we are concerned to make sure
that you are working safely when you:
• Build circuits
• Trace circuits through a vehicle
• Test circuits for voltage, current or resistance
• Replace parts in electrical systems
What hazard controls can you use to ensure your safety?
2.1 Hazard Control

To control a hazard we need to reduce the risk of the hazard occurring. This means reducing the
impact of the hazard by either:
reducing the consequences or reducing the likelihood.
Some hazard control techniques:
• Idle hand behind back
• Disconnect leads from wall or ceiling socket
• Cords and tools checked and tagged – don’t use tools that are not tagged and current
• Wear rubberised, insulating footwear and insulating gloves
Activity 1 – Electrical Controls (Respond Online)

Working with your partner to think of controls for each type of work listed below. Share your ideas
with others in your training group.
Build circuits
Trace circuits through a vehicle
Test circuits for voltage, current or resistance
Replace parts in electrical systems


Topic 3 - Electrical Principles
3.1 Electrify in Vehicles
Electricity is in everything we do, everything we touch. Every particle of the universe is made up of
atoms which contain electrically charged particles. We’ll look at that in more detail shortly. But, what
does electricity do? You already know the answer to this.
Activity 2 - Electrical ...or Not? (Respond Online)
Make two lists:

Six things that need electricity to work
Six things that don’t need electricity to work.
Now make one more list – what features on a car need electricity?
Are there any features on a vehicle that don’t use electricity?


3.2 Electricity and the Atom – Protons, Neutrons, Electrons
Atomic Structure
Your desk top is made of a material such as wood or synthetic. That material is made up of
molecules. Molecules are extremely small and can only be seen with the most powerful microscopes.
Molecules are made of even smaller particles called atoms (‘atom’ is a Greek word meaning ‘can’t be
split’). There are about 114 known types of atom from Hydrogen – the smallest – to Plutonium – one
of the biggest.
Even though we thought atoms couldn’t be split we have since found that they are made up of smaller
particles called:
• Protons –in the centre or nucleus and with a positive electrical charge
• Neutrons – also in the nucleus but with no charge
• Electrons – circling around the nucleus with a negative charge.
Even though these particles can be split, we have gone far enough for the moment. (Remember the
Higgs-Boson?)
Substances
Molecules Molecules
for example
Atoms Atoms Atoms Atoms
Electrons Protons Neutrons

A Lithium Atom


Currents of Electrons
You don’t have to be Einstein to know that the electrons circling the nucleus can flow from one atom
to the next creating an electric current. Electrons are arranged into shells or orbits. Carbon has six
electrons in two shells – the inner shell has two and the outer shell has four. Carbon doesn’t conduct
electricity very well because it is very stable.
Substances with only a few outer shell electrons make good conductors. Copper (29 electrons –
shown here), silver (47) and gold (79) all have only one electron in their outer shell. This one electron
can move easily to the next atom, and the next and the next creating a flow or current of electricity. In
an electrical circuit the electrons flow to the positive pole on a power source – a battery or a
generator.

Outer Shell Electron Flow – Cu Atoms
3.3 Electrical Current: Conventional vs Electron

Partly because some ideas about electricity were decided before atoms were understood, an electric
current is said to run in the opposite direction to the flow of electrons. We call this ‘conventional
current flow’ and the electron movement we call ‘electron flow’.
Question: Which would be the best conductor - carbon with 4 outer shell electrons, hydrogen with 2
or sodium with one?

Electron Flow Conventional Current Flow


3.4 Current, Voltage, Resistance and Ohm’s law
Now that we have established what electricity is we can begin looking at how to work with it.
There are three aspects of electricity that we can measure and control to make electrical systems
operate. These are:
Current (Symbol ‘I’)*

• When water is flowing in a river a certain
volume of water passes a point in one second
– this is called the current.
• When electricity is flowing in a wire a certain
amount of electricity passes a point in one
second – this is also called a current
Force (Symbol ‘V’)*

• Water travels with a certain amount of force
based on what is happening up stream.
• Electricity travels with a certain amount of force
based on the strength, or voltage, of the battery
or generator powering the circuit.
Resistance (Symbol ‘R’)*

• The banks of the river restrict the river and limit
the flow of current. They offer resistance. If
they are closer together the resistance is high
and further apart, the resistance is lower.
• In an electrical circuit resistance is determined
by the type of conductors the electrical current
is flowing through. To put it simply – a good
conductor gives a low resistance and a poor
conductor gives a high resistance.


3.5 How do we measure the aspects of electricity?
23
Current is measured in amperes (amps). A one amp current is 6.3 billion billion or 6.3 x 10 electrons
(Avogadro’s constant) passing a point in one second.
Electromotive force (EMF) is measured in volts. One volt is a 1 amp current giving off one Watt of
power or the force obtained from a small (AA) battery
Resistance is measured in ohms. One ohm is the resistance when a one volt force produces a one
amp current.
If we take these ideas and put them together we get Ohm’s Law which is:
Current = Voltage / Resistance or I = V/R
3.6 Types of Electricity – Variations on a Theme

There are many variations on the concept of electricity. Some of them overlap but that doesn’t matter.
Here are some variations on ‘electricity’.
• Static electricity - made by rubbing together two or more objects and making friction while
• Current electricity - the flow of electric charge through a conductor
• Photovoltaic electricity - produced when light is converted into current electricity
• Piezoelectricity - produced when two crystal-based materials are pushed past each other
• Chemical – the reaction that produces electricity in a battery is a source of electricity
• Mechanical – most electricity is produced by the mechanical movement of one object past another
inducing electrical current flow
• Alternating current – current alternating between positive and negative in a regular pattern
• Direct current – current flowing continuously at a set level


Activity 3 - Using Electricity (Respond Online)
Try to match each of the variations listed to an aspect of everyday life:
Example: Static electricity - this is produced when synthetic cloth is pulled over human hair. The hair
becomes charged and sometimes stands on end.
Current electricity
Photovoltaic electricity
Piezoelectricity
Chemical
Nuclear
Mechanical
Alternating Current
Direct current
Answers in Appendix 1


3.7 Learning Check for Electrical Principles (Respond Online)
1. The best conductors have how many electrons in their outer shell?
2. A conventional electric current flows towards which electrode?
3. The symbol for current is: 5. Electricity made by rubbing two objects
together is called:
a. V
a. Static
b. I
b. Chemical
c. W
c. Alternating
d. R
d. Photovoltaic
4. Which version of Ohm’s law is correct? 6. The three parts of an atom are:
a. V = IR a. Proton
b. I = R V b. Boson
2
c. I=B c. Neutron
d. None of the above d. Electron
7. What is the force component of an electric current called?


Topic 4 - WHS/OHS for Electrical Practices
Contact with electrical circuits even as low as 24v can have an effect on the human body. That is
because muscular control is achieved with electrical impulses in the nervous system. The nervous
system’s control of muscles can be disrupted by externally induced electric current flows (commonly
known as “electric shocks”). If the heart muscles were affected then cardiac arrest could result. Even
relatively minor muscular contractions can have unfortunate consequences such as dropping objects,
falling off ladders etc. When large voltages are involved a combination of loss of muscular control and
large currents flowing in the body can result in overheating and burning of tissue. A good example of
this is when someone is struck by lightning and it can also happen when a person is exposed to live
wires.
Electricity should be regarded as a hazard and steps should be taken to avoid exposure to it.
4.1 Electrical Hazards - The Science of Electric Shock

The primary variable for determining the severity of electric shock is the electric current which passes
through the body. This current is of course dependent upon the voltage and the resistance of the path
it follows through the body.
One instructive example of the nature of voltage is the fact that a bird can sit on a high-voltage wire
without harm, since both of its feet are at the same voltage. You can also see that the bird is not
"grounded" -- you will not be shocked by touching a high voltage if there is no path for the current to
reach the Earth or a different voltage point.
Modern vehicles have a lot of complex electrical circuitry which can store charge. This stored charge
can be released or ‘discharged’ when a route to ground is supplied. If you touch a vehicle that is
storing charge you may become the route to ground and experience an electric shock. This shock
could kill an unsuspecting mechanical technician. Wearing the correct PPE – insulating gloves,
rubber-soled shoes in particular – provides good (but not perfect) protection from discharge current.


4.2 Current Involved in Electric Shock
The electric current (in amperes) is the most important variable when determining the severity of an
electric shock. However, this current is in turn determined by the driving voltage and the resistance of
the path which the current follows through the body. One difficulty in establishing the conditions for
electrical safety is that a voltage which produces only a mild tingling sensation is one case can be a
lethal shock hazard under other conditions. Will 120 volts produce a dangerous shock? It depends!
If your body resistance is 100,000 ohms, then – using the I = V/R equation - the current which would
flow would be:
I = V = 120 volts = 0.0012A = 1.2mA
R 100,000 ohm
This is the threshold of perception and would only feel like a tingle. But if you have just played a
couple of sets of tennis, are sweaty and barefoot, your resistance to ground might be as low as 1000
ohms. Then the current would be:
I = V = 120 volts = 0.12A = 120mA
R 1,000 ohm
This is a lethal shock capable of causing the heart to fail. The severity of shock from a given source
will depend upon its path through your body.
4.3 Shock Physiological Effects

Voltage required to produce the current:
Electric Current Physiological Effect Body resistance - Body resistance - 1,000
(1 sec. contact) 100,000 ohms ohms
1 mA Threshold of feeling, tingling 100 V 1V
sensation.
5 mA Accepted as maximum 500 V 5V
harmless current
10-20 mA Beginning of sustained 1000 V 10 V
muscular contraction ("Can't let
go" current.)
100-300 mA Ventricular fibrillation, fatal if 10000 V 100 V

continued. Respiratory function
continues.
6A Sustained ventricular 600000 V 6000 V

contraction followed by normal
heart rhythm. (defibrillation).
Temporary respiratory
paralysis and possibly burns.


4.4 Hazard management techniques
Electric Shock
Contact with an electric current can cause chest spasm and cessation of breathing. It can also cause
the heart to stop and may cause burns. Workshop electrical emergencies can result from:
• A faulty switch or appliance cord

• Contact between an electrical appliance and water
• Damaged power lines, following a storm or traffic DRSABCD Action Plan
accident DANGER
• Lightning strike Ensure the area is safe for yourself, others and the
patient.
RESPONSE
Signs and Symptoms of Electrical Injuries Check for response—ask name—squeeze
After an incident or accident, survey the scene and look shoulders
No response Response
for objects burned by power lines, cords or appliances • Send for help. • make comfortable
near the victim. The following are signs and symptoms • check for injuries
• monitor response.
of an electrical injury: SEND for help
Call Triple Zero (000) for an ambulance
• Unconsciousness, respiratory arrest, cardiac arrest or ask another person to make the call.
• Entry and exit burns on the victim where the AIRWAY
electric current passed through the body Open mouth—if foreign material is present:
• place in the recovery position
• Signs and symptoms of shock • clear airway with fingers.
Open airway by tilting head with chin lift.
First Aid for Electrical Injuries BREATHING
Your first concern is to make sure the electric current is Check for breathing—look, listen and feel.
Not normal breathing Normal breathing
no longer present. • Start CPR. • place in recovery position
• monitor breathing
• Do not touch the victim until you are certain of this. • manage injuries
• In the case of a regular power tool, switch off the • treat for shock.
CPR
main power or remove the plug if it is safe to touch Start CPR—30 chest compressions : 2 breaths
the supply cord. Continue CPR until help arrives
• In the case of high voltage or current, such as a or patient recovers.
fallen power line or industrial equipment, stay at DEFIBRILLATION
Apply defibrillator if available
least 6 metres away from the power line and follow voice prompts
• Call the local power authority and wait for the
arrival of trained staff or for assurance that the © ASA
power has been turned off.
When it is safe to approach the victim of an electrical

injury, follow the DRSABCD chart shown here.


4.5 Learning Check for Electrical Safety (Respond Online)
1. At low levels electric shock results in….?
2. At high levels (high voltage and high current flow) electric shock results in ….?
m. Can cause death

3. The primary factor determining the severity
of electric shock is: n. Prevents you from letting go
e. Voltage o. Gives a tingling sensation
f. Current p. Is below the threshold for feeling
g. Weather
6. Imagine you are in contact with a moist
h. Wind surface and touch a conductor carrying 240
volts. First estimate your resistance:
4. A current of less than 1milliAmp for 1
q. 1 ohm
second
r. 1000 ohm
i. Can cause death
s. 10,000 ohm
j. Prevent you from letting go
6
t. 10 ohm
k. Give a tingling sensation
l. Are below the threshold for feeling

5. A current of more than 300 milliAmp for 1
second:
7. Calculate the current that will flow through you if you are in contact with a moist surface and touch
a conductor carrying 240 volts.
8. For the answer you have given to question 7. - what type of shock would you experience?


4.6 Personal safety
There are a number of steps you can take to ensure you are safe working with electrical systems.
These include:
 Insulation gloves – Class O gloves have an
insulating leather outer covering and a rubber
inner glove. These gloves can resist voltages up
to 1000 volts
 Safety goggles or glasses – these should
include side shields and should be worn at all
times when you are within 15 meters of a vehicle.
 Rubber-soled shoes - these are non-conductors
that isolate you from an earth-ground preventing a
current from flowing through your body
 Natural fibre clothing – cotton, woollen or linen
clothing does not conduct a current while some
synthetics are good conductors and therefore
dangerous
 Jewellery, watches, neck chains – any metal on
your body is a potential strong conductor which
can increase you chance of receiving an electric
shock
 Pencils, pens or tools in pockets – like
jewellery, metal objects in pockets increase the
risk of electrocution

Activity 4 - What to Wear
Let’s process that information - label the diagram of

an apprentice mechanic about to work on an electrical system:
• What should he be wearing?

• What shouldn’t he be wearing?
Locate the safety equipment mentioned in your workshop.


Topic 5 - Electrical Circuits
When electricity flows through the systems of a vehicle – the lighting system or the ignition system, for
instance - it is following an electrical circuit. Electricity in a circuit flows from a power source, through
conductors to a device then back to the power source. There are many circuits in a modern vehicle.
These circuits can be drawn using symbols and they can be measured and tested using meters to
find faults.
In this topic we will look at electrical circuits in general then look at how these ideas apply to motor
vehicles.
5.1 Components of a Circuit

An electrical circuit is made up of:
1. Power Source – a battery or generator
2. Conductor – usually copper wires
3. Protection – a fuse which burns out
before the rest of the circuit is damaged
4. Load – the device the circuit is driving
(a light, starter motor, gauge)
5. Control – a switch or similar mechanism
to allow the circuit to be controlled
5.2 Load
Any device such as a light, spark plug,
wiper motor or radio, which consumes electricity, is called a load. In an electrical circuit, all loads are
regarded as resistance. Loads use up voltage and control the amount of current flowing in a circuit.
Activity 5 - Electrical Loads (Respond Online)

Make a list of as many ‘loads’ as possible in five minutes


Automotive Electrical Circuits
In an electrical circuit in a motor vehicle, one end of the wire from each load is connected to the
vehicle body or frame. This means the vehicle body acts as a conductor allowing current to flow
though the body and back
to the battery. This is
referred to as a body
grounding.
5.3 Ohms Law

Ohms Law is the
relationship between
voltage, current and
resistance in electrical
circuits. Understanding this
relationship is important for
fast, accurate electrical
problem diagnosis and
repair.
Ohm's Law says: The current in a circuit is proportional to the voltage and the amount of resistance.
Or to express it mathematically as we did earlier:
Current = Voltage / Resistance or I=V/R
This simple equation can be expressed three ways and all are correct – they simply allow us to
calculate all three variables. The other versions are:
Voltage = Current x Resistance or V=I x R

and Resistance = Voltage /Current or R=V/I
In its simplest form we know that: 1 volt will push one amp through 1 ohm of resistance. Here’s a
more detailed example:
A circuit has a battery supplying 12 Volts of power. The resistance in the circuit from a light is 2 Ohm.
What is the current?
If I = V / R then I = 12 Volts / 2 Ohm = 6 Amp


5.4 Circuit Symbols
To draw circuits quickly and to read them
easily a set of symbols have been
developed. The table here shows some
common symbols.
Circuits drawn with these symbols are
included in vehicle manuals so that
electrical systems can be traced through
a vehicle and tested at the appropriate
points.
Applying the Theory

We will construct a simple circuit based
on a description then use Ohm’s Law to
calculate an unknown.
The circuit is in a vehicle so it is
grounded to the body.
The battery is supplying 12 volts
The load – a motor - is imposing 4 ohms of resistance.
There is a switch in the circuit.
What current is flowing?
Current Calculation
We know I = V / R so
I = 12 volts / 4 Ohms
I = 3 Amp
V = 12v If you were doing fault finding on this vehicle

R = 4 ohm M
you would now expect the current in the
circuit to be 3 Amp and if it wasn’t you would
have a problem that needs further testing.
Vehicle Body


5.5 Voltage Drop
Voltage drop is a measurement you will make to locate faults in an electrical system. There are
several things we can say about voltage drop:
• Voltage drop is the amount of voltage that is used by a load in an electrical circuit.
• All voltage supplied to a circuit by its power source (i.e. battery) will be used up in the circuit.
Therefore, the sum of the voltage drops will equal the supplied voltage. (Kirchhoff’s Law)
• A voltage drop measurement is done by measuring the voltage before entering the load and the
voltage as it leaves the load. The difference between these two voltage readings is the voltage
drop.
Voltage Drop – One Load
This circuit has one load – a
Motor
In the simplest case – a single
load on a circuit – all the
voltage will be used by the one V = 12v 12V
R = 4 ohm M
load. The voltage drop is
always drawn in the way shown
here. In this case the voltage
drop is 12v
Vehicle Body
R = 4 ohm
Voltage Drop – Two Loads
This circuit has two loads – a
Lamp and a Motor
6 V When there are two or more
V = 12v M loads the voltage drop of each 6 V
R = 4 ohm
load is proportional to the
resistance of that load. In the
case shown here the two loads
have the same resistance (4
ohm) so the voltage is equally
Vehicle Body shared. The voltage drop is 6
volt for each load. Voltage drops in a circuit should add up to the voltage of the power source.


Voltage Drop – Two Loads and Unequal Resistance
This circuit has two loads – a light and a motor.
In this case the lamp has a high
R = 1 ohm resistance and consumes more
volts. What current flows through
it? We know that V = IR and from
this we know that I = V / R. If we
add the values we know 3 volt and
1 ohm we get:
3 V
I = 3 / 1 = 3 Amp
V = 12v 9 V
R = 3 ohm M So, a three Amp current is running
through the Lamp
The current in the motor is:
I = 9 / 3 = 3 Amp
In a vehicle with a fault in an electric
Vehicle Body motor, the motor and lamp could be
tested to ensure they are receiving the appropriate current.


5.6 Parallel Circuits
A parallel circuit provides two or more
paths for the current to follow. This allows a
number of components to be supplied with
electricity from a single lead or source.
The voltage for each path is always the
same as the voltage source – usually 12
volt – so the resistance of each load V = 12v M
determines the current in each leg or shunt.
In this example the Lamp load current is
given by I = V / R or I = 12 / 1 = 12 Amp
The Motor current is given by I = V / R or I
= 12 / 3 = 4 Amp.
In this case if there is a fault in this parallel Vehicle Body
circuit you would test for current passing
through each load and look for values
different to our calculation
Activity 6 – Series and Parallel Circuits

(Respond next page)
Draw the circuit (here or on the next page) and calculate the current through each load for each of the
following scenarios. Answers in Appendix 2
1. A series circuit with one load – an interior lamp for a car. The power supply is 12 volt and the load
imposes a resistance of 1.2 ohm
2. A series circuit with two loads – two wind screen wiper motors. The power supply is 12 volt and
each motor imposes a resistance of 6 ohm.
3. A parallel circuit with a parking light of 1.2 ohm resistance and a dashboard indicator lamp of 2.4
ohm.


Activity 6 – Series and Parallel Circuits - Record answers here


5.7 Sample Wiring Diagram: Headlight Circuit
Circuit diagrams used by auto electricians are usually much more complex that any we have seen so
far. And, being more complex they are often hard to read. On this page we have a relatively simple
circuit diagram for vehicle headlights. We have included a guide for reading this diagram.
Reading a wiring diagram:

Battery (B+) connects with
Two relays (R6) which complete

the circuit going via
Fuses to the
Head lamps
BCM with switches to grounds

control the circuit
All the lamps are grounded

through grounds G102 and G104


5.8 Circuit Faults
Circuits can have three main types of faults – short circuits, open circuits and high resistance.
Short Circuits
A circuit in which the
current by-passes some High Resistance –
of the load on the circuit. corrosion or loose Open Circuit –
terminals Switch Open
This usually involves the
power side of the circuit.
Open Circuits
No current flows through
any part of the circuit
because there is a break
in the circuit.
High Resistance
A circuit in which the
load does not receive
the current required to
function normally. This
is often caused by
corrosion, loose
terminals or poor
grounding.
Activity 7 – Wiring
Diagram Short Circuit
Find and download a (to ground)
vehicle wiring diagram.
Note the URL where you
found it. How hard or easy is it to read?


5.9 Electrical Power
Where Watts come from – In Life

Long ago in the 1970’s there was a band called Billy Thorpe and
the Aztecs. They had a sound system that ‘pulled 300 watts of
power’. This was unheard of in the ‘70’s and everyone wanted to
be blown away by the Aztecs at their famous live gigs. Billy is no
longer with us but his memory lingers on.
(Ask your parents or grandparents about ‘Thorpie’)
Billy Thorpe & Jimmy Barnes
Where Watts come from – In a motor vehicle

So, what has this got to do with motor vehicles? Well, cars and trucks use electric power and we need
to keep an eye on the power – levels involved in a vehicle’s electric circuits or things can go wrong.
Remember the headlight circuit we looked at earlier. There are four headlights – two low beam and
two high beam. Each of the high beam lights uses 60 watts of electric power when they are on. The
low beams use 55 watts. If we think about ‘Thorpie’ - the high beam on your car head lights uses 120
watts or 1/3 of the power that Thorpie used to blow away an audience.
Now, add to that the idea that the alternator generates electric power to charge the battery and at the
same time it runs all the electrical functions on a car. A modern
alternator produces about 1440 watts of power so, if you have
multiple high beam lights and other electrical equipment running,
that’s going to use a lot of the power from the generator and
possibly some of the stored power in the battery.
It’s easy to see how a flat battery can result from using too much
power on car sound systems and the like.
High & Low Beam Headlights


Working with Power
Revisiting Ohms Law

The equation for Ohm’s Law V=I x R allows us to make predictions about the ohms, amps
or volts in an electrical circuit. If we test the circuit and don’t get the predicted reading we know there
is a fault.
The Power Equation

There is a similar equation for power. It is P=IxV and it says multiply current I by
volts V to get the power in watts. If we know a circuit is running at 10 amps and 12 volts then the
power in the circuit is 10 x 12 = 120 watts.
Here’s another variation. Using Ohms law we can say that V = I x R or V /R = I If we feed
2
this into the Power Equation we get P = V/R x V or P = V /R. In other words we can calculate
power if we know the volts and the resistance. This can be used to predict results in fault finding, too.
For instance, if we know the voltage is 12 volts and the resistance is 10 ohms then the power should
be P = 12 x12 / 10 = 144/10 = 14.4 watts
We can also switch the equation around to get other values.
You have a load which is in a circuit with a voltage of 12 volts and a current of 5 amps. What can we
calculate? (See the Activity)
Activity 8 – Power Calculation

What is the power level for this device?
What is the resistance of the device?
The Future in Electricity

Electrical systems are complex and go
beyond the scope of this study so we will
leave it there. But, consider this – electric
vehicles are increasing in number around the
world. Toyota produces a part electric car in
Australia. This could be the way of the future.
Auto electrical technicians will be in demand
in your future. Think about that when
planning your career.


Topic 6 - Tests and Faults
This Study doesn’t require you to perform complex testing and fault finding although your instructor
may arrange for you to experience some testing tasks. What you do need is an understanding of the
equipment used to find faults and some of the faults most commonly found.
6.1 Testing Equipment

Modern systems for maintaining and repairing
motor vehicles are becoming more complex –
multimeters, computer interfaces – and at the
same time easier to use. A correctly used
multimeter can identify a circuit failure in
seconds and will supply information that old
systems would not. Computer diagnostics not
only take the reading they do all the calculations
and can often pin point the fault to a specific
point on a circuit. Thankfully, technicians are still
needed to repair the fault and report back to the
customer.
Here are some of the commonly used testing
and diagnostic tools available in most
workshops.
6.2 Multimeter
A multimeter is an electronic measuring
instrument that combines multiple
measurements in one unit. A typical multimeter
can measure voltage, current, and resistance.
Most multimeters are digital and are referred to
as a DMM (digital multimeter). The digital read
out is much more accurate that older meters
that used a needle to indicate readings.
Modern digital multimeters may have an embedded computer, which provides many useful features
including:
• Auto-ranging, which selects the correct range for the quantity. For example, displaying a reading
as 1.234 milliamp instead of 0.0012 amp
• Auto-polarity for direct-current readings, shows if the applied voltage is positive or negative
• Sample and hold, which stores the most recent reading for use after the test is complete
• A low-bandwidth oscilloscope useful in some automotive tests
• Automotive circuit testers, including tests for automotive timing.


6.3 Multimeter Operation
Your skill with the DMM will increase as you use it and
a lot of your experience will come from applying
common sense. Here are some tips and pointers that
will help you get started:
• The DMM comes with two leads. Normally you Test Leads
would put the black lead into the COM terminal and
the red into the V terminal as shown.
• To take a voltage reading such as a battery test first attach the red lead to the positive (+) terminal
of the battery and the black lead to the negative (-) terminal. Select DC Volts – a V with a straight
and a dashed line above. V
• The operator of the DMM must select the terminal
suited to the current they expect when measuring
current.
• The DMM is usually fused for a maximum of 10 Amp
and the unit will be damaged if more than 10 Amp is
applied. It is common to put an external fuse on one
of the leads so that it will burn out protecting the
DMM.
• Learn what the dial settings mean and are used for.
The diagram below gives a summary.
Test Lead terminals
Activity 9 – Reading Circuits

Take the following readings:
Voltage in a car battery
Resistance in your body
Resistance in a light bulb
Resistance in a windscreen wiper motor


6.4 Test Lamp
A test lamp also called test light or voltage tester is a http://www.ipdusa.com/newsletters/63/557/fuse-‐kit-‐test-‐light-‐disconnect-‐switch-‐battery-‐pal-‐battery-‐accessories
simple device used to determine the presence or

absence of an electric voltage in a piece of
equipment under test. One end is adapted to attach
to the battery or vehicle ground. The other end is a
probe that can be touched on any circuit that may be
faulty. If a voltage is detected the light illuminates.
These devices may attach with a clip. Some Test
Lamps work off induced current and only need to be
held near the circuit to detect voltage.
These devices can be used for safety testing either
in vehicles or in any other work that could involve a

dangerous electrical circuit. Telecommunications
workers use them extensively.
6.5 Battery Tester

The image shows a domestic battery charger with a built in tester with a power or charge level
indicator. There are two forms of test for batteries - load
test and conductance test
Load Test
A load tester puts a load on the battery and assesses how
the battery reacts. If after a load the battery charge level is
above 9.6 v it is serviceable and can be recharged and
used.
Conductance Test
Conductance is the ability of a battery to conduct current.
Testers use internal circuitry to determine this then report
to the user to:
• Return the battery to service

• Charge and retest the battery
• Replace the battery
The charger shown here is a small domestic charger which measures volts only.


6.6 Insulated hand tools
Electrocutions have often been a major cause of work related fatalities. Work on electrical
components and systems poses a high risk of
injury, especially when the tools you use are om/300seri/307serie.htm
good conductors.
All hand tools used on electrical components
should be insulated to reduce the risk and
consequences of an electrical contact.
The highest voltage that insulated tools can
withstand is 1000 volts AC and 1500 volts DC.
Working on motor vehicles this should be
enough to protect you. Insulated tools should
be in compliance with
• IEC 60900: Live working – Hand tools for
use up to 1000 V a.c. and 1500 V d.c.; or
• AS 3527.2: Hand-operated screwdrivers
and screwdriver bits – Insulated
screwdrivers.
Guidelines from the NSW Industry Steering

Safety Committee:
• Before use, insulated tools shall be
checked to ensure that there is no damage to or deterioration of the insulation.
• Insulating tools shall be routinely tested according to a testing regime that takes into account such
factors as the usage, handling and storage.
• Any low voltage insulated tool failing the above inspections/tests shall be removed from service as
a low voltage insulated tool.
Activity 10 – Failure to Insulate (Respond Online)

What are the potential consequences of not using insulated tools?


6.7 Computer interface – OBD Functions
A scan tool is a computerised device which can read
the information captured by on-board computer systems

(called Onboard Data or OBD) and operate components
on the car via those on-board systems. Scan tools are
used both in manufacturing vehicles and in maintaining
them.
A typical scenario for using a scan tool is when a
warning light comes. This means a fault has occurred
and a diagnostic trouble code (DTC) has been set on
the on-board computer. A scanner can be used to read
the code and begin a fault finding process. The normal
sequence of events is:
• Locate the data link connector (DLC) they are often
located under the dash
• Connect the scanner to the DLC
• Turn the ignition key to on (engine not running)
• Enter the vehicle identification number (VIN)
information requested
• Use the on screen options to read data and store data for printing
The last step will result in you having one or more DTCs to act on. Use a fault finding technique to
locate and repair the faults then test drive the car to ensure all problems have been repaired. If all is
working normally clear all DTC from the on-board computer and return the car to the customer.
This process makes fault finding much more efficient and accurate giving the customer better service
than has been possible in the past.
Activity 11 – OBD Interface (Respond Online)

Find the OBD interface on at least three vehicles – try
a car yard or family and friends. Where is each
interface located?

Under0dask OBD Port
Vehicle Type OBD Location


6.8 Fault Finding Technique
Fault finding in automotive electrical systems is one form of problem solving. There are many ways to
solve a problem but they all have a lot in common when you look at them closely. Automotive fault
finding is usually done with a DMM in your hand. You will be looking for current flow or high resistance
levels in circuits that are not functioning properly. It is important that you have a pattern to follow so
that you find the fault as efficiently as
possible. One well used method is called
the 5 point process.
What is the five point process for fault
finding technique?
1. Learn the system
2. Consult the customer
3. Locate the fault
4. Repair the fault and re-test the system
5. Determine the cause
Each of these deserves closer attention
1. Learn the system - if you are not familiar
with it. You will need to trace the circuits
that make up each system to begin the process of finding where the fault is occurring
2. Consult the customer – ask the customer what happened when the fault occurred? Which indicator
lights came on or went off? What else can they tell you that might help locate the fault?
3. Locate the fault - by testing each section of the circuit. This will be spelt out in more detail below
4. Repair the fault - and re-test the system. The repair might be replacing a fuse or rewiring a section
of circuit. Be sure that once you’ve repaired the fault it is not reoccurring.
5. Determine the cause - and take steps to prevent it occurring again if your repair hasn’t done this
already.
Point 3 – In detail
This is the ‘real’ fault finding process. Here is a simple process that uses a DMM (Digital Multimeter):
1. Make a simple circuit diagram for the faulty system/circuit to ensure you know what you’re testing
(or obtain a circuit diagram from the internet)
2. Set you DMM for Ohm readings
3. Turn off the system so that no current is flowing
4. Connect one lead of the DDM to the load side of any circuit fuses - having checked that the fuse is
not the problem
5. Follow the first wire in the circuit and test it for resistance
6. A good circuit will read 0 (zero)
7. Continue down each branch of the circuit until you find a positive reading for resistance – this
indicates a fault; probably a faulty motor or light
Here you can return to the five step process to complete the fault finding.
6.9 Extra Information

There are some excellent sources of general information and the process of fault finding. The video
listed here is a starting point for your own search.


Dan Sullivan – How to use your multimeter voltmeter: Voltmeter trouble Shooting
http://www.youtube.com/watch?v=b-4Up4Jskdc
Online Diagnostic Flow Charts

Manufacturers supply diagnostic flow charts via the internet. These can be used to quickly and
accurately find and rectify faults. Here are some URLs.
http://www.electrosport.com/technical-resources/library/diagnosis/pdf/fault-finding-diagram.pdf


6.10 Common Faults
There is a saying that, in life and in business, whatever can go wrong will go wrong. Whether this is
true on or not there certainly are a lot of things that can go wrong in a typical modern vehicle. Here
are some common faults. In the first two cases we have suggested fault finding actions. In the last
three you can suggest fault finding actions. We would be looking for tests that involve electrical testing
but might also include physical examination.
Battery failure
Source of Failure/Cause Test Action
• Battery failure due to age • Use a DMM to test the • Recharge or replace battery
battery.
• Alternator failure • Use a DMM to measure • Remove corrosion on wires
voltage output from & at junctions
generator • Replace alternator
• Current leakage • Measure for current flow in • Trace leakage and repair
vehicle with all systems off.
No ignition
• Are there OBD fault codes? • Use an OBD scanner and • If there are active faults
check for fault codes. take the relevant action
• Is it the starter motor? • Check for mechanical • Remove corrosion on wires
operation & at junctions
• Check for voltage drop • Replace starter motor
using a DMM
• Check for resistance
• Is it the coil? • Check for voltage drop • Remove corrosion on wires
• Check for resistance & at junctions
• Replace coil
Windscreen wiper failure

• Motor • •
• Wiring • •
• Switch
Indicator light failure

Dimming headlights


Topic 7 – Identify and Locate Electrical Systems
In this part of the Study you will identify each electrical system in a motor vehicle and their component
parts, determine how each system operates and explain how this contributes to the overall operation
of the vehicle. To take some of the guess work out of it we have listed all the electrical systems found
in a motor vehicle below.
Activity 12 - Electrical Systems and Components (Respond Online)

We have completed the first three ‘common faults’ examples for you. Either by your own research or
in your interview with a mechanic in Topic 6 identify the other seven common faults.
System Traditional Modern Operations Common Faults

Components Components
Ignition • Ignition Coil • Sensors – • Spark plugs • Sparkplugs
• Distributor CKP and CMP ignite fuel in the oxidising and
• Spark Plugs • Ignition control cylinders failing to
module (ICM) • The coil converts spark
• Spark Plugs 12V from the
battery to 5,000
to 40,000 V at
the spark plugs-
• Distributor or
Ignition Control
times the firing of
the spark plug
Charging • Alternator • Alternator • The alternator or • Alternator
• Battery • Battery generator is wear causing
driven by a drive poor charging
belt of the battery
• The alternator • Flat battery
generates current
which recharges
the battery
Starting • Starter motor • Starter motor • The battery • Starter drive
(Cranking) • Battery • Battery provides a burst fails to
• Starter • Starter of current to the engage with
solenoid solenoid starter motor fly wheel
• Starter Drive which rotates the
• Starter Drive
• Ignition Switch engine crank
• Ignition
shaft helping to
Switch
start ignition in
the motor
• The solenoid
controls the flow
of current into the
starter motor
• The starter drive
connects the
starter to the
engine fly wheel
to rotate the
engine.
• Ignition switch
controls the
starter process


Engine • Pre-set • Electronic • The ECU reads
Management controls in the Control Unit or values from
carburettor ECU sensors within
the engine bay,
• It interprets data
using
multidimensional
performance
MAPs,
• Actuators on the
engine adjust to
ensure optimal
engine
performance.
Lighting • Brake lights • Brake lights • Brake lights
• Courtesy • Courtesy lights illuminate when
lights • Headlights the brake pedal
• Headlights • Turning is depressed and
indicators the brake light
• Turning
• Interior lights switch is closed.
indicators and
hazard • LED Display • Courtesy lights
indicators lights and interior lights
are operated by
• Interior lights
the passenger to
complete the
circuit for the light
• Indicator and
hazard lights are
activated by the
indicator leaver
and a flasher unit
in the circuit
switches the
lights on and off.
• LED display
lights usually
signal a warning
based on a
reading from a
sensor
Remote Door Not found on • Control unit – • Control unit
locks, older vehicles usually sends RF signal
Windows and integrated with to car
Boot Release ignition key • Sensors on the
• Servo-motors vehicle receive
to operate signals
locks • Sensors activate
• Sensors to servo-motor to
receive signals open or close the
door, window or
boot


Electronic Not found on • Sensors • Engine mounted
dashboard older vehicles • Control unit to sensors and
gauges process other sensors
sensor changes in
information vehicle status–
• Dash mounted e.g. seat belts
gauges not applied or oil
level drop
• Control unit
processes sensor
information
• Dash mounted
gauges are
illuminated to
report status
change
Wiper/washer • Control switch • Control switch • Vehicle operator
• Motor and • Variable switches on
sweep arms sweep control wipers
• Wiper arms • Motor and • Wiper speed set
and rubber sweep arms by operator
blade • Wiper arms • Wiper motor
and rubber drives wipers
blade • Some current
vehicles have
automatic rain
detection and
wiper speed
setting.
Entertainment • Radio • Radio • Modern cars
• CD Player have an audio
• iPod port system
• DVD player integrated into
the vehicles
electronics
network.
• Details are
beyond the
scope of this
Study.
Wiring Loom • Fuse block • Multiple • A wire harness
and under dash bundles of is an assembly of
Fuses/Circuit • Electrical wires with wires which
Breakers wiring common path transmit signals
coordinated and/or or electrical
from this purpose power.
point • Replaceable • The cables are
• Replaceable fuses or trip bound together
fuses switches • Binding the many
wires into a cable
harness, the
wires can be
better secured


Activity 13 – Researching System Functions
Objective:
To build a portfolio of information about electrical components in motor vehicles.
Method:
What is your favourite make and model of car? Imagine you are left a run down version of this car by
a rich old grandparent on the condition that you restore it to perfect condition on your own. The first
step would be to collect information about each system in the car from sources such as:
• Manufacturer’s website
• Part supplier’s website
• Notice boards and Blogs
• Owner’s manual
• Car Club
• Any other source you can think of – including speaking to people who have information on your
car.
When you find these information sources print or photocopy one or two pages of the information that
is relevant to an electrical system. Some information sources may have information for more than
one system – that’s OK. You must find at least eight information sources.
Put all your collected information into a portfolio. Make a list below of the titles of each source you
have found and the electrical system it applies to.
This may make up an important part of your assessment. You will submit:
The table on the next page completed with information for each system
Sample pages from your information sources
Your instructor/assessor/teacher will observe you as you identify the location of each system on a
modern vehicle.


Sources of Electrical Systems
Information
Fuses/Circuit Breakers
Engine Management
Entertainment
Wiper/washer
Boot Release
Wiring Loom
Door locks
Charging
Windows
Lighting
Starting
Ignition
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.


Sources of Electrical Systems
Information
Fuses/Circuit Breakers
Engine Management
Entertainment
Wiper/washer
Boot Release
Wiring Loom
Door locks
Charging
Windows
Lighting
Starting
Ignition
14.
15.
16.


Topic 8 – Field Work
It is said that mechanical faults often take little time to find but hours to repair while electrical faults
take hours to find and minutes to repair. How true is this?
You can use it as part of this training activity – a way
to start a conversation with the mechanic you
interview.
And, yes, this is a lot like the task in Vehicle Systems.
Activity 14 – Whose fault is it?
Purpose:
Investigate the electrical faults found in motor vehicles
Method:
• Interview a working mechanic or car enthusiast
• Alternatively, look at range of internet forums
• Identify a type of vehicle the mechanic is familiar with
• Discuss and note the common electrical faults for that type of vehicle
• Discuss and note some common solutions to those faults
• Present this information to your instructor and/or your training group



Appendix I - Answers
Learning Check for Electric Principles
1. One or two electrons
2. Negative
3 The symbol for current is - I
4. Ohm’s law is - V = I R
5. Electricity made by rubbing two objects together is called Static
6. The three parts of an atom are – proton, neutron, electron
7. The force component of an electric current is called the voltage or electromotive force or EMF
Knowledge Check for Electrical Safety

1. Loss of control of nerves and muscles.
2. Overheating and burning of body tissues
3. b. Current
4. d. Are below the threshold for feeling
5. a. Can cause death
6. b. 1000 ohm
7. Use the formula V/R = I 240 V/1000 Ω = 0.24 Amp or 240 milliAmp
8. A shock causing heart failure (fibrillation) and possibly death.
Types of Electricity
• Static electricity - Walking on synthetic carpet then touching metal
• Current electricity - Electricity as we know it
• Photovoltaic electricity - Solar Panels
• Piezoelectricity - Barbeque lighter
• Chemical – Car or torch battery
• Mechanical –Generator
• Alternating current – normal wall socket power
• Direct current – car or torch battery


Appendix 2 – Circuit Diagrams
1. A series circuit with one load – an interior lamp for a car. The power supply is 12 volt and the load
imposes a resistance of 1.2 ohm
2. A series circuit with two loads – two wind screen wiper motors. The power supply is 12 volt and
each motor imposes a resistance of 6 ohm
3. A parallel circuit with a parking light of 1.2 ohm resistance and a dashboard indicator lamp of 2.4
ohm
1. I = V / R, so
I = 12 v / 1.2
I = 10 / 1 = 10 Amp
V = 12v 1.2 ohm
Vehicle Body
2. I = V / R, so
for both loads
M
I = 12 / 6
V = 12v I = 2 / 1 = 2 Amp
M
Vehicle Body
3. I = V / R, so
for the parking light
I = 12/1.2 =
10 Amp
For the dash light
V = 12v 1.2 ohm 2.4 ohm I = 12 / 2.4 = 5 Amp
Vehicle Body


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Electrical

This learner workbook AURETR003 Apply

This publication has been produced with the assistance of

• Basic electrical principles

Special Note - Mechanic Interview

http://www.aboutmyplanet.com/science-­‐technology http://cleanfuelconnectionnews.com/electric-­‐vehicles/ http://www.mnn.com/green-­‐tech/transportation/

2.1 Hazard Control

Activity 1 – Electrical Controls (Respond Online)

Trace circuits through a vehicle

Test circuits for voltage, current or resistance

Replace parts in electrical systems

Activity 2 - Electrical ...or Not? (Respond Online)

Make two lists:

Six things that don’t need electricity to work.

Are there any features on a vehicle that don’t use electricity?

Atoms Atoms Atoms Atoms

Electrons Protons Neutrons

3.3 Electrical Current: Conventional vs Electron

Electron Flow Conventional Current Flow

Current (Symbol ‘I’)*

Force (Symbol ‘V’)*

Resistance (Symbol ‘R’)*

3.6 Types of Electricity – Variations on a Theme

2. A conventional electric current flows towards which electrode?

7. What is the force component of an electric current called?

4.1 Electrical Hazards - The Science of Electric Shock

4.3 Shock Physiological Effects

100-300 mA Ventricular fibrillation, fatal if 10000 V 100 V

6A Sustained ventricular 600000 V 6000 V

• A faulty switch or appliance cord

When it is safe to approach the victim of an electrical

1. At low levels electric shock results in….?

m. Can cause death

e. Voltage o. Gives a tingling sensation

f. Current p. Is below the threshold for feeling

l. Are below the threshold for feeling

• What should he be wearing?

Locate the safety equipment mentioned in your workshop.

5.1 Components of a Circuit

Activity 5 - Electrical Loads (Respond Online)

5.3 Ohms Law

Current = Voltage / Resistance or I=V/R

Voltage = Current x Resistance or V=I x R

Applying the Theory

V = 12v If you were doing fault finding on this vehicle

Activity 6 – Series and Parallel Circuits

Two relays (R6) which complete

BCM with switches to grounds

All the lamps are grounded

Where Watts come from – In Life

High & Low Beam Headlights

Revisiting Ohms Law

The Power Equation

Activity 8 – Power Calculation

What is the resistance of the device?

The Future in Electricity

6.1 Testing Equipment

Test Lead terminals

Activity 9 – Reading Circuits

Resistance in your body

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