Electric System Suzuki

EN05 Engine Auxiliary System I Starting system 1

Basic electrical

Electrical / Electronics Course code: GE02

Student training manual

Suzuki Online Training

GE02 Electrical/Electronics I Basic electrical 2

Foreword For many years, electrical technology has been used in the motor vehicle to power up important on-vehicle functions like headlights, engine ignition system, the radio, etc. It is very important for the automotive technician to understand basic electricity. In this course, we will study the fundamentals of electricity and electrical systems in a motor vehicle. Smart manuals Some sections of this training manual contain videos with detailed information on the topics you are studying. If you are studying this training manual on a PC, look out for the green play video symbol on any photo or picture in this manual, click on the green button to watch a video providing you with detailed information on that topic. Note: Internet connectionrequired.

Suzuki Technician curriculum This training manual is part of the Non Suzuki Technician to Suzuki Technician curriculum. The curriculum consists of the following modules: 1. GE01 Suzuki Introduction 2. GE02 Electrical / Electronics 3. Diagnostics 4. EN02 Engine Mechanical part I 5. En03 Engine Mechanical part II 6. EN04 Engine Mechanical part III 7. EN05 Engine Auxiliary systems 8. DS01 Driveshaft/Axle 9. DS02 Driveshaft/Axle transfer case 10. BR02 Brake control systems 11. Manual transmission / transaxle 12. CS02 Control system / body electrical 13. CS03 Communication / bus systems You are currently studying EN05 Engine Auxiliary Systems. This module consists of the following courses: Basic electrical Basic electronics

Click on the other training modules to view training contents.

This document is intended solely for training purposes only. All vehicle repairs and adjustments must be carried out according to the procedures stipulated in current service manuals and technical bulletins.

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Table of contents Page Fundamentals of electricity 4 Electricity 5 Current, Voltage and Resistance 6 Ohms law 7 Voltage ( DC and AC) 8 Resistance 9 Temperature and resistance 10 Connection of resistors in a circuit 11 Electromotive force 13 Effects of electric current 14 Heating effect 14 Chemical effect 15 Magnetic effect 16 Electromagnets 17 Magnetomotive force and Electromotive force 17 Electromotive force caused by conductor motion 19 Mutual induction 20 Principles of DC motors 20 Principles of AC motors 22 Power sources 26 Complete electric circuit 26 Power distribution 27 Fuse boxes 28 Fuses 29

Page Relays 31 Relay operation 32 Voltage spikes 33 Suzuki wiring diagrams 35 Wiring colors 36 How to read power supply diagram 37 How to read system circuit diagram 38 How to read ground circuit diagram 39 How to read connector codes & terminal numbers 40 Electric circuit inspections 44 Basic precautions for circuit inspection 44 Voltage measurements 47 Resistance measurements 49 Current measurements 51 Oscilloscope 53

GE02 Electrical/Electronics I Basic electrical

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Fundamentals of electricity Objectives At the end of this lesson, you will be able to: Explain the principles of electricity Describe voltage, resistance and current Define Ohms law Describe direct current voltage and alternating current

voltage Describe the qualities of good conductors, semiconductors

and non conductors Explain what is meant by a series circuit, parallel circuit and

mixed circuit. Describe the different effects of electrical current. Explain the operating principle of electromagnets Explain the operating principle of mutual induction Explain the operating principle of a DC motor Explain the operating principle of an AC motor

GE02 Electrical/Electronics I Basic electrical

GE02 Electrical / Electronics I Basic electrical 5

The atom All matter is made of atoms. The atom is the smallest part of any matter and it contains the following parts: Proton Neutron Electron

A nucleus is at the centre of the atom and it contains the Proton (Positively charged) and a nucleus (No electrical charge). The electrons orbit the nucleus. The maximum number of electrons found in the valence (outer) ring is 8 and this number depends on the type of material. An insulator for example, has 6 or more electrons in the valence ring, and a good conductor has 3 or less electrons in the valence ring.

Electricity Electricity is the movement of electrons from one atom to the next atom in a conductor such as a piece of wire. In electrolyte, the movement of ions also produces electricity. Only the FREE ELECTRONS in the outermost shell (Valance Ring) are free to move from atom to atom. This movement is called ELECTRON FLOW. These FREE ELECTRONS are loosely held and can easily be moved to another atom or ion. Because of their distance from the nucleus, free electrons have a weak magnetic attraction. Since this attraction is not as strong to the nucleus as the bound electrons on the inner orbits, the electrons move easily from atom to atom.

Figure 1 Atom [a] Proton [b] Electron [c] Nucleus [d] Neutron


Current, Voltage and Resistance We often hear that electricity flows, but we cannot directly see electricity. However, if we consider flow of electricity as flow of water, we can easily understand. If we connect two tanks of different heights with a hose and fill water in the higher tank, the water will flow from the higher tank to the lower tank through the hose, as shown in figure 2 below.

This is because by the action of the force of gravity the water flows from a higher level to a lower level. The water flows because there is a difference in levels. The difference of levels is called potential energy of water. Same is the case with electricity. Electricity flows from the positive side to negative side because there is a difference of potential similar to difference of water levels. The quantity corresponding to water level difference is called electric voltage and the quantity corresponding to flow of water is called electric current. With same difference of water levels, the wider the connecting hose, the easier it is for water to flow, and vice versa. This is because there is fluid friction between the hose and water which increases resistance. In case of electricity also, the thicker is the wire the easier it is for electricity to flow, and vice versa. The quantity that represents this difficulty of flow is called electric resistance.

Figure 2 Electricity and water tank analogy [1] Water pressure [2] Thin pipe connecting tanks [3] Flow of water, resistance is small, water flow is low [4] Same water pressure as 1 [5] Thick pipe [6] Flow of water, resistance is small, water flow is large.


Units used for voltage, current and resistance

Ohms law Ohms law was discovered by a German physicist Ohm in 1826. Ohms law states that current flowing through a conductor is proportional to the voltage between those two points and inversely proportional to the resistance between them. This can be represented by the following formula: V(E) = I X R Example of Ohms law application: Question: What is the current flowing in a circuit that has a 12V power supply and a 10 resistor connected in series? I = V / R I = 12 / 10 I = 1.2 A

SI unit/symbol Conversion Instrument used to measure

Voltage (U ) V (Volt) 1V=1000mV 1kV=1000V

Voltmeter

Current (I) A (Ampere) 1A=1000mA Ammeter

Resistance (R) (Ohm) 1 = 1000m 1k=1000

Ohmmeter


Voltage Voltage is the pressure that is applied in a circuit to enable current flow and it is not dependent on current or voltage. There are two kinds of voltage and current namely direct current (DC) voltage and alternating (AC) voltage. DC (Direct Current) voltage In direct current (DC) the direction of flow is constant, but there are two types in one type the direction and size both are constant and in other type the direction is constant but the size changes (pulsates). A motor vehicle electrical system uses DC voltage.

Alternating current

On the contrary in alternating current (AC) both the direction and size always change. Direction and size of AC change with time, but generally it is a repetition of the waveform between A and B shown in figure 5. The 220 volt electricity supplied to houses and the electricity generated by a motor cars alternator are AC. Time required for repeating this one cycle is known as period T (in seconds) and number of repetitions per second is known as frequency, f (Hz).

Figure 3 - direction and size constant [v] Voltage [t] time

Figure 4- direction constant, size changes [v] Voltage [t] time

Figure 5 - Alternating current [T] Period in seconds [F] Frequency in Hz [1] Voltage [2] Time [Vo] Maximum value [Ve] Effective value [Vpp] Peak to peak value


Resistance Resistance is how easily current can flow through a conductor material. Conductors are classified into three categories namely, good conductors, semiconductors and non-conductors. Resistance is not affected by voltage or current in a circuit. It is either ok, too low or too high. When resistance is high, current flow will be low and when resistance is low, current flow will be high. Good conductors Substances which let electricity flow easily are called good conductors or simply conductors. Metals such as silver, copper, aluminum and iron, etc. are typical conductors and nonmetals like carbon or electrolyte of a battery, etc. are also conductors Non conductors Substances that do not let electricity flow easily are known as non-conductors. Rubber, glass, fiber, resin, etc. are non-conductors and are used as insulators by using their property of high electrical resistance. Semi-conductors The resistance of semiconductor changes when activated by electricity, heat, light or magnetic field. Semiconductors are being widely used in transistors, diodes, thermistors and CCD (charge-coupled devices).

Resistance according to shape of conductor Even in a wire of same material, electrical resistance differs according to the length and thickness of wire. It is directly proportional to the length and inversely proportional to the area of cross section of the wire.

Resistance Type Material

Large Non-conductor (Insulator)

Polystyrene

Rubber Glass Fiber

Semiconductor Silicon Selenium Germanium

Good conductor Graphite Nichrome Copper Iron Aluminum

Small Silver

Figure 5 R = L/A


Positive Temperature Coefficient (PTC) In PTC type materials like common metals, the resistance increases as temperature increases. Negative Temperature Coefficient (NTC) In NTC type materials such as semiconductors, the resistance decreases as temperature increases.

Contact resistance If resistance exists between contacting surfaces when connecting electric wires, not only that flow of electric current is oppressed but also the surfaces get oxidized due to generation of heat and their resistance increases. Resistance developed at contacting part in this manner is called contact resistance. Contact resistance can be decreased by removing the oxides from the contacting surfaces and by increasing the contact pressure or contact area. Therefore, polishing contact parts, soldering and increasing tightening force prove effective in decreasing contact resistance.

Temperature and Resistance Even if material and shape are constant, resistance of a substance changes with temperature. The change rate of resistivity for 1C rise in temperature is called temperature coefficient. Resistance of a metal increases with increase in temperature. This is because as temperature rises, thermal vibration of positive ions of metals atoms becomes severe and free electrons collide with the positive ions more frequently, resulting in speed down of electron. Resistance of semiconductors sharply decreases with rise in temperature. This is because when temperature is low, the electrons in semiconductor are bound to the atoms and there are less free electrons. But as temperature rises, free electrons increase by receiving thermal energy. Figure 6 Resistance vs. Temperature [a] Common metals (PTC) [b] Semiconductors (NTC) [R] Resistance [T] Temperature

Figure 7 Contact resistance is common between the battery post and cable.


Connection of resistors in a circuit Resistors in an electrical circuit can be connected to each other in the following ways: Series connection Parallel connection Mixed connection

Series connection In a series connection, the resistors are connected in line. Current passes through each resistor before it reaches ground. The resistors in the following circuit are connected in series. If connection to one of the loads is broken, the complete circuit is turned off. Most Christmas tree lights are connected is series.

Formulas for series connection NB: t= total Rt = R1 + R2 + R3 Vt = V1 + V2 + V3 It = I1 = I2 = I3

Voltage drop When more than one load exists in a circuit, the voltage divides and will be shared among the loads. The sum of the voltage drops equal source voltage. The higher the resistance the higher the voltage drop. Depending on the resistance, each load will have a different voltage drop.

Figure 9 Series connection


Parallel connection In a parallel connection, the resistors are connected as shown in figure 10. If connection to one of the resistors is broken, the other resistors continue to function. Electrical loads in the motor vehicle are connected in parallel. In a parallel circuit, Vt = V1 = V2 = V3 This means that the voltage measured at any part of the circuit is equivalent to the supply voltage, It = I1 + I2 + I3 (Kirchhoffs fist law) 1

= 1

1 + 1

2 + 1

3 or Rt = (1 2 3)(1 + 2 + 3)

Kirchhoffs laws First law: Current law The sum of currents flowing into each junction is equal to the sum of currents flowing out of that junction. Mixed circuits (series-parallel circuits) When performing calculations on the mixed circuit, first calculate the total resistance of the parallel circuit, then add this to the resistance of the series resistor. Activity: considering figure 11, calculate the total resistance of the circuit if the resistance of the variable resistor was at 100 and the bulbs were 10 and 12 respectively.

Figure 10 Parallel connection

Figure 11 Mixed circuit


Electromotive Force and Internal resistance of electric source A device, such as a battery, that applies voltage to a circuit and causes current to flow is called an electric source. In other words an electric source can be regarded as a device that acts to raise electric charge inside the device to a high potential. Voltage between both terminals of an electric source when no current is flowing is called electromotive force. When drawing current by connecting a variable resistance R to an electric source of electromotive force E as shown in the figure below, it seems that the current can be increased to any extent by decreasing R, but it does not happen because the electric source also possesses resistance. Resistance of an electric source is called internal resistance. When there is internal resistance, the voltage (terminal voltage) between both terminals of electric source decreases from electromotive force by an amount equal to the voltage drop due to internal resistance. In the lead storage battery used in motor vehicles, the internal resistance is the sum of the electrical resistances of the plates, electrolyte and connectors, etc.


Effects of electric current Electric current has the following effects in a circuit: Heating effect (Electric bulb, cigarette lighter, fuse) Chemical effect (Electric plating, electric polishing) Magnetic effect (electric motor, generator, horn)

Heating effect Heat is generated when an electric current flows through a conductor. The amount of generated heat is directly proportional to the product of the square of the current flowing through the conductor and the resistance of the conductor. This relationship is shown by the following equation:

Joules law (Reference) 1 W s (watt-second) = 1 J 1 kg . m = 9.8 J This is known as the Joules law. The Joules law was experimentally discovered by an English physicist Joule in 1840. The amount of heat generated Q is the amount of work done by the electric energy in the form of heat energy and therefore it is equal to the amount of electric energy. This electric energy is called electric power. Not only work done in the form of heat energy, but total amount of work done by electricity is called electric power and is represented by watt-second (Ws) or kilowatt-hour (kWh) unit. Generally capacity of electric devices such as brightness of an electric bulb or capacity of an electric motor is represented in terms of watts (W). This unit represents the amount of work done by electricity in 1 second, that is, it represents electric power. Example: A 12V 70W bulb (figure 13) means [70W brightness], but actually it means that, when connected to an electric source of specified voltage, it converts 70W of electric power to light and heat.

Figure 12 Heat effect equation : Q = IRt Q (J) : Heat generated R (ohm) : Resistance I (A) : Current t (sec) : Time

Figure 13 Headlight bulb


Specified voltage is different for different bulbs. Even if rated voltage is 12V, specified voltage is not strictly 12V. P = I E = I x I x R = Q/t P (W) : Electric power (watt W) E (V) : Voltage (V) I (A) : Current (A) (Reference) 1PS (horse power) = 0.7355 KW 1kgf.m/sec = 9.8 W 1PS is equivalent to the amount of work needed to raise a 75kg object by 1m.

Chemical Effect When an electric current flows in water or an electrolyte, it produces chemical effect. A substance that undergoes chemical effect by means of an electric current is called an electrolyte. Electrolysis means electric decomposition, that is decomposition of an electrolyte into molecules or atoms by means of electricity. This phenomenon is called electrolytic dissociation or ionization and the dissociated molecules and atoms are called anions and cautions respectively.

When an electric current flows through a dilute solution of sulfuric acid (4), oxygen gas is produced at the (+) electrode and hydrogen at the (-) electrode. This is because the sulfuric acid (4) in the liquid splits into hydrogen ion (2) and sulfate ion (1), the hydrogen ion releases its (+) charge at the electrode and becomes hydrogen gas and the sulfate ion releases its (-) charge by reacting with water and becomes oxygen gas and sulfuric acid. This electrolysis is used for making oxygen and hydrogen. It is also widely used for electric plating and electric polishing in industry.

Figure 14 Chemical effect [1] Sulfate ion [2] Hydrogen ion [3] Current [4] Dilute sulfuric acid (H2SO4) [Pt] Platinum


Magnetic Effects When electricity flows through a wire of conductor, a magnetic phenomenon appears around the wire. For example, when we place a magnetic compass under a wire and apply electric current to the wire, the needle of the compass moves, as shown in the figure below. Or, as shown in the below figure below, iron powder gets arranged along the magnetic field, showing that a magnetic field has been produced. The direction of this magnetic field is clockwise with regard to the direction of flow of the current as shown in the figure. This is called right hand screw rule or right hand thumb rule.

Magnetic field produced by coil To effectively use the magnetic field produced by a single wire, it is better to make a coil by bending the wire in the form of circle. This produces a magnetic field as shown in the figure below. In this case if we regard the direction of flow of current as the direction of rotation of screw, the magnetic field is produced in the direction of advance of right hand screw. A circular current like this can be regarded as a collection of DC currents gradually changing the direction. Since the lines of magnetic force produced by each of these DC currents are in the same direction inside the coil, a strong magnetic field can be produced inside the coil. The larger the number of turns of the coil, the stronger the magnetic field because each turn of the coil produces same magnetic field which combine together inside the coil to form a strong magnetic filed.

Figure 15 [1] Right hand thumb rule [2] Right hand screw rule [3] Current [4] Battery [5] Iron powder [6] Conductor

Figure 17 magnetic field produced by a coil


Electromagnets The lines of magnetic force produced by a coil are similar to the lines of force produced by a bar magnet. The magnetic field produced by the current flowing in the coil has no polarity but it is only an aggregate of lines of force inside the coil. Therefore we can imagine that there are virtual magnetic poles at both ends of the coil. As shown in figure 16 below, a magnetic force strong enough to pull the piece of iron does not develop by applying current to the coil. But if we insert an iron core into the coil, the magnetic field produced by the current magnetizes the iron core. The magnetic flux (lines of magnetic force form a flux) increases. The iron core becomes a strong magnet and pulls the piece of iron, as shown in the figure below on the right. Such magnets are called electromagnets (solenoid).

Example: The principle of electromagnets is used in relays Magnetomotive force and electromotive force If we form the iron core in frame shape and wind a coil on it, as shown in figure 18(A), and let an electric current flow through the coil, most of the generated magnetic flux passes through the iron core because it is easier for magnetic flux to pass through iron core than through air. Such route of magnetic flux is called a magnetic circuit. Many magnetic fluxes pass through this magnetic circuit and strongly magnetize the circuit, but magnetic poles can not be produced. But if we make a gap in the core as shown in the figure 18(B) below, magnetic poles appear at this part and lines of magnetic force proportional to the magnetic flux in the core are produced in the gap.

Figure 17 Relay

Figure 16 [1] Magnetic flux [2] Current flow [3] Iron piece [4] Iron core


The strength of magnetic flux produced in magnetic circuits is determined by the current flowing in the coil and the number of turns of the coil. The force that produces this flux is called magnetomotive force. If we place a piece of wire in between the magnetic poles so that it can easily move, as shown in the figure 18(C) below, and let a current flow through it, a force acts on the wire and the wire moves. If we reverse the direction of the current, the wire also moves in opposite direction. The force that moves the wire in this case is called electromagnetic force.

Cause of generation of Electromagnetic Force The magnetic field produced between magnetic poles is a uniform field, as shown in figure 19(a) below. If we place in this magnetic field (see figure 19(c) below) a wire producing a circular magnetic field (see figure 19(b) below), the magnetic field on the left side of the wire becomes stronger because the two magnetic fields are in same direction and the magnetic flux becomes denser, but on the right side of the wire the flux becomes weaker because the two magnetic fields cancel each other. Since magnetic flux always tends to be uniform, the wire receives a force in right direction as shown in figure 19(d) below.

Figure 18 Magnetomotive force and electromotive force [a] Current flow [b] Gap [c] Electromagnetic force

Figure 19 [1] Magnetic flux is strengthened and becomes dense [2] Magnetic flux is weakened and becomes coarse


Electromotive Force caused by motion of conductor If we connect a galvanometer (very sensitive ammeter) to the conductor and move this conductor in between the magnetic poles, an electric current is generated in the conductor and the galvanometer shows deflection. This experiment reveals the following facts. The galvanometer deflects by moving the conductor as well

as by moving the magnet. Deflection of galvanometer stops by stopping the movement. The direction of deflection in galvanometer changes by

changing the direction of movement. The faster the movement, the larger the deflection of

galvanometer. In this manner, when a conductor cuts a magnetic flux by any method, an electromotive force is generated in the conductor. Moreover, the size of electromotive force is proportional to the rate of cutting lines of magnetic force (lines of magnetic force cut in one hour).

Electromagnetic Force caused by change of magnetic flux Self induction Change of magnetic flux around a coil of wire produces current. In figure 21 below, if we move the magnet in and out of the coil, the galvanometer needle moves indicating an electromotive force.

Figure 20 [1] Galvanometer (measures current flow) [2] Electromotive force caused by movement of conductor

Figure 21 [3] Galvanometer [B] Permanent magnet


Mutual induction If we wind two coils (primary coil and secondary coil) on the same iron core as shown in figure 22, a magnetic flux is generated around the primary coil when power is supplied to the coil. When the power is cut-off, the magnetic flux collapses and cuts through the secondary coil. An electromotive force is then induced in the secondary coil. This principle is used in the ignition coil of an igniter in which the current of primary coil is interrupted by means of transistor or contact point and the electromotive force produced in the secondary coil is used for producing a spark.

Principles of DC Motors When a coil of wire is connected to a battery, as shown in the figure 23(1) below, the current flows into the coil through the brush. Composite lines of magnetic force are generated according to the right hand rule as shown in figure 23(2). The coil on north pole side received a force in left direction. The coil on south pole side received a force in right direction and in this way a rotating torque is generated. The direction of this torque coincides with the direction determined by the Flemings left hand rule.

Figure 22 Mutual induction [1] Primary coil [2] Secondary coil [3] Galvanometer

Figure 23 Principles of DC motor [a] Commutator [b] Current flow [c] Battery [d] Turning force [e] Coil in line of magnetic force


However, if the direction of current flowing through the wire is always constant, it cannot rotate more than 90 degrees from the position shown in the figure below. By reversing the direction of current after every half rotation by using a commutator, as shown in the figure 24 below, the direction of current flowing in the wire can be kept constant in the vicinity of magnetic poles and thus rotation can be continued. This is the principle of operation of an electric motor.

Actuator motor In an actual motor, many commutators and coils are used in order to eliminate non-uniformity of rotation and achieve constant and uniform rotation, but the basic principle is the same. The direction of rotation of a DC motor is determined by the direction of magnetic field and the direction of current flowing in the armature coil according to Flemings left hand rule. Therefore, the direction of rotation of motor can be reversed by keeping the direction of magnetic field as it is and changing the direction of armature current or by keeping the direction of armature current constant and changing the direction of magnetic field.

Figure 24 Principles of DC motor

Figure 25 Actuator motor armature [1] Coils [2] Commutator

1

2


The principle that when a current flows in a wire placed in a magnetic field, the wire receives a force is used in electric motors. In small motors (such as wiper motor, electrical window motor, etc.) a permanent magnet is used to produce the magnetic field. However, since it is difficult to make large size permanent magnets and use of such magnet will increase the cost, in starter motor the coil is wound on an iron core and it is used as an electromagnet by applying current to it. This coil is called field coil and its iron core is called field core. The following methods of connection of field coil and armature coil are used. The starter motors of a motor vehicle uses the series motor. Series motor (a) Shunt motor (b) Compound motor (c)

Principles of AC motor (Alternator) Principle of electric generation Since magnetic flux is cut by moving either the coil or the magnet in a combination of a magnet and coil, an electromotive force is generated in the coil by the effect of electromagnetic induction, as shown in the figure 27[a] below. In an alternator the electromotive force is generated by rotating the magnet as shown in the figure [b] below. The rotor uses electromagnet achieved by winding a coil on iron core and applying a current to it. The coil used to produce the magnetic field is called rotor coil and the fixed coil that generates electricity is called stator coil.

Figure 26 Field coil, armature connection

Figure 27 Principles of AC motors [a] Principles of AC generator [b] Principles of Alternator [1] Coil [2] Rotation of magnet [3] Rotation of coil [4] Rotor [5] Slip rings [6] AC output [7] Stator


Change of electromagnetic force generated in Coil In an electric generator electromotive force is generated by rotating the coil or magnet. At this time the direction and angle by which the coil cuts the magnetic flux always change resulting in change in the following variables: Change of Direction of Electromotive force Change of Size of Electromotive Force If we represent this with a graph, we find that it is an AC electromotive force of the shape of a sine curve as shown in the figure 28 below.

Figure 28 Sine wave produced by AC electromotive force [E] Electromotive force [X] Angle of rotation of rotor (6 = 180, 12 = 360)


Summary Electric current is the movement of electrons from one atom

to the other in a conductor. It takes on volt to push one amp through a one ohm resistor Ohms law states that current in a circuit is directly

proportional to the voltage in the circuit and inversely proportional to the resistance in the circuit.

Conductors are grouped in to three categories namely, good conductors, non conductors and semiconductors

In NTC type materials, the resistance increases when the temperature decreases and in PTC type materials, the resistance increases when temperature increases.

The principle of electromagnets is used in a relay. The principle of mutual induction is used in ignition coils The principle of AC motors is used in motor vehicle

alternators. The principle of DC motors is used in motor vehicle starter

motors.


Electrical circuits Objectives At the end of this lesson, you will be able to: Describe the basic components of an electric circuit. Describe the power source, system and ground circuit. Describe the function of fuse boxes Describe the tasks and functions of fuses and relays. Read and interpret Suzuki wiring diagrams Describe the basic precautions that must be adhered to

when performing electrical circuit measuring and repair. Describe the procedures to perform voltage, resistance and

current measurements using a digital multimeter.


Power sources In a motor vehicle, the alternator and the battery are the power sources of the electrical system. When the engine is not running, the battery is the power source for all electrical loads and if the engine is running, the alternator generates the electrical energy to supply to the electrical loads and to charge the battery.

Complete electric circuit An electric circuit of a motor vehicle is generally configured as shown in figure 3. The current from the positive terminal of electric source battery passes through fuse or circuit breaker used for protecting the circuit, then a switch used to control the circuit, then through the load and then returns to the negative terminal of the battery via the vehicle body. Figure 3 - Electrical circuit

Figure 1 Alternator An alternator uses the principle of AC motors to generate electrical energy for the electrical loads and recharging the battery

Figure 2 Battery The battery produces electricity through a chemical reaction and also stores electricity supplied by the alternator or a battery charger

sandilemTypewritten Text


Power distribution There are many loads that operate on the battery voltage and the loads are connected in parallel with the electric source as shown in figure 4. The main current distributors are the fuse boxes., The circuit from electric source plus terminal to the fuse and up to the switch is called the power source circuit. The circuit from the switch to the load is called system circuit and the return circuit from the load to the negative terminal of the battery is called ground circuit. In this manner electric circuit of a motor vehicle can be divided into power source circuit, system circuit and earth circuit. In order to efficiently perform work, electric wiring diagram showing colors of wiring, locations of electric devices or harness, earth point, locations of connector terminals, etc. is used in addition to electric circuit diagram when conducting inspection and repair of electric devices of motor vehicles

Figure 4 - Power supply circuit

Battery Main fuse box

Individual circuit

fuse box No.1

Ignition switch


Main fuse box A main fuse box is used in Suzuki vehicles. This fuse box is the first power distribution point in the vehicle and it is connected to the battery positive terminal. The individual circuit fuse box No. 1, the alternator and the ignition switch are all connected to the main junction box. These circuits are protected by high current fusible links.

Individual circuit fuse box The individual circuit fuse box contains lots of fuses used to protect different circuits in the motor vehicle. The individual circuit fuse box can be located in the engine compartment and also inside the vehicle. It also houses relays for control of some circuits. The allocation of each fuse and relay in the fuse box is printed in the cover of the fuse box. Always replace a fuse with a fuse of the same rating.

Figure 5 Main fuse box

Figure 6 Individual circuit fuse box (Suzuki Swift)


Circuit protection devices Fuses, fuse elements, fusible links, and circuit breakers are used as circuit protection devices. Circuit protection devices are available in a variety of types, shapes, and specific current ratings.

Fuses Fuses are the main common circuit protection device. A fuse is placed in series in a circuit so that when current supply to a load exceeds the rating of a fuse, it melts and breaks the circuit to the load to protect the load.

Fuse types

Figure 7 Blade type fuses [a] Standard auto fuse [b] Maxi fuse [3] Mini fuse

a b c

Figure 8 Fuse element cartridge

Figure 9 Main fuse box fusible links

Figure 6 Fuse


Color coding for standard and mini fuses Color coding for maxi fuses

Color coding for fuse element type Identification color Fuse Amp rating

Pink 30 A

Green 40 A

Red 50 A

Yellow 60 A

Black 80 A

Blue 100 A

Identification color Fuse Amp rating

Yellow 20 A

Green 30 A

Amber 40 A

Red 50 A

Blue 60 A

Brown 70 A

Colorless 80A

Identification color Fuse Amp rating

Violet 3 A

Tan 5 A

Brown 7.5 A

Red 10 A

Blue 15 A

Yellow 20 A

Colorless 25 A

Green 30 A


Relays Relays are used to control circuit to particular loads (e.g. Headlights, horn, etc.) Relays allow a small current flow to control a large current flow. Relays can be switched on via contact switches or by transistors in control modules like the ECM. A relay is made by winding a coil of wire around a soft iron core. When current is supplied to the coil of wire, a magnetic field is formed around the coil attracting a contact switch. The contact switch closes or opens the circuit depending on the design of the relay.

Types of relays

Horn switch

Contact coil

Horn relay

Figure 10 Suzuki Alto Horn circuit


Relay operation A 4 pin relay has 4 electrical connections to it. These connections are usually labeled 30, 85, 86 & 87. The pins of some 4 relays are labeled 1, 2, 3 & 4. In most relays, the circuit diagram of the relay is printed on the relay housing for easy reference. Considering the horn circuit in figure 10, when the horn switch is closed, current flows from fuse 31 to the relay solenoid. This causes a magnetic flux to form around the solenoid which attracts the contact switch and closes the circuit. This enables current to flow from the fuse to the horn, then to ground and the horn will operate.

Relay pin Designation

30 or 3 From power source to relay switch

87 or 4 From relay switch to electrical load

85 or 2 Power supply to solenoid

86 or 1 Solenoid ground


Voltage spikes When a relay solenoid circuit is closed, current flows through the relay and creates a magnetic field around the solenoid. When the circuit to the relay is open, current stops flowing through the relay solenoid. This causes the magnetic field around the solenoid to collapse. When magnetic field collapses around the solenoid coil, voltage that can be as high as 200 volts is momentarily induced in the coil. This is called voltage spike and it can damage sensitive electronic control units.

Voltage suppression relays Relays controlled by electronic control units require protection from voltage spikes. To achieve this, a diode or resistor is connected across the solenoid to suppress the voltage spike. In the relay with a de-spiking diode, a diode is connected across the solenoid as shown in the figure below. When the voltage increases above 7 V, the diode becomes forward bias and allows current to flow through it, allowing the current to flow to the back of the coil. The current flows around in the diode and coil circuit until the voltage is dissipated.

Figure 11 Voltage spike

Figure 12 Relay with de-spiking diode


A high ohm resistor can also be used in place of the diode. In this relay, the resistor is positioned as shown in figure 13. A resistor is more durable than the diode but are not quite as efficient at suppressing a voltage spike as diodes.

Figure 13 Relay with de-spiking resistor


How to read Suzuki wiring diagrams Suzuki wiring diagrams are designed in this format and must be read from the top of the page to the bottom of the page. The power source circuit (a) is at the top of the page The system circuit (b) is in the centre of the page and The ground circuit (c) is at the bottom of the page.

a

b

c


Wiring colors The following wiring color symbols are used in Suzuki vehicles. There are two types of wire color used. One is the single colored type and the other is the dual colored (striped) type. The single colored type uses only one color or symbol. The dual type color uses two color symbols (i.e. GRN/BLK in the figure below ). The first symbol represents the base color of the wire (GRN in the figure below) and the second symbol represents the color of the stripe (BLK, in the figure below)


How to read power supply diagram


How to read system circuit diagram [A] Fuse No. [B] Circuit jumping page / direction [C] Circuit jumping point / direction [D] Terminals in-one-connector [E] Wire color [F] Shield color [G] Ground point [H] From or To with ID letter(s) [I] Specification variation [J] From [K] To [L] Connector code [M] Terminal No. [N] Symbol mark [O] See mark


How to read ground circuit diagram


How to read connector layout diagram (Refer to figure 14 in the next page) [A-1] : Harness symbol and corresponding harness name A: Battery cable B: A/C harness C: Engine harness D: Injector harness, Oil pressure switch wire E: Main harness, Power steering wire F: Console wire G: Instrument panel harness, Instrument panel antenna wire J: Side door wire (incl. P/W related wires) K: Interior light harness, Roof wire, Roof radio antenna wire, Rear speaker wire L: Floor harness, Floor antenna wire, Coupling harness, Accessory socket wire, G sensor wire M: Rear bumper harness O: Rear end area harness/wires (except Rear bumper harness) Q: Side curtain-air bag wire, Side-air bag harness, Pretensioner harness R: Fuel pump wire S: Contact coil [A-2] : Connector Number [B] : Ground point No.


Figure 14 Connector layout


How to read connector codes and terminal numbers 1) Connector code/Terminal No./Terminal layout The connector shape and terminal layout shown in the wiring are those when viewed from Z in the illustration.

2) Connector types i) Male connector plugged directly on component

ii) Male to female connector on a component pigtail harness

iii) Male to female connector


3) Terminals in one connector (Broken line) (B15) Terminals in different connectors (B14, B16) 4) Joint connector (J/C) Several different wires with the same wire color are joined at

a part of J/C.

5) Weld splice (W/S) Several different wires with the same wire color are joined

by welding at a W/S

6)Junction block (J/B)


Electric circuit inspection The digital multimeter is the most common tool used for circuit measurements. Depending on the type of digital multimeter being used, most common multimeters will have these basic functions. For detailed information of how to use your digital multimeter, refer to its owners manual. Voltage Resistance Current Diodes Temperature Frequency Other functions, depending on the model

Basic precautions for circuit inspection Precautions when using the digital multimeter Never connect any tester (voltmeter, ohmmeter or

whatever) to terminals of an electronic control unit when its connector is disconnected. Doing so may cause damage to the electronic control unit.

Never connect an ohmmeter to an electronic control unit with its connector connected to it. Doing so may cause damage to electronic control unit and sensors.

Be sure to use only the specified voltmeter / ohmmeter. Otherwise, accurate measurements may not be obtained or personal injury may result. Where no voltmeter type is specified, use a voltmeter with high impedance (M /V minimum) or a digital type voltmeter.

Always connect the multimeter is SERIES to the circuit when measuring CURRENT (A).

Always move the RED probe to the CURRENT port on the multimeter before measuring current.

Always observe the MAX current the multimeter can measure. Connecting the multimeter to a circuit with current exceeding the MAX current will damage the multimeter.

Always connect the multimeter in PARALLEL when measuring VOLTS or OHMS.

When measuring resistance, always disconnect any power supply to that circuit.

Replace the multimeter batteries when they are flat. Using a multimeter with flat batteries results in inaccurate readings.

Figure 15 Digital multimeter (Major Tech MT21 model shown)


Electrical circuits inspection method It is important that the technical follows a logical and methodical method to diagnose and repair a fault in the electrical system of a motor vehicle. Whilst there is no single way of diagnosing and repairing of electrical circuit, the following method is a guideline to ensure the diagnosis is reduced and improve Fix Right First Time

Step 1 : Verify Before you can successfully diagnose any electrical faults, you need to verify and make sure you understand the existing fault.

Step 2: Isolate After verifying the fault, you can then begin with the isolation procedures. The troubleshooting section of the service manuals must be followed when isolating and this includes the following: Checking of power supply circuit, fuses and relays (1) Checking of the circuit controls and switches (2) Checking of the system circuit (3) Checking the electrical load (4) Checking the ground circuit (5)

Step 3: Repair Repair or replace faulty components and wiring

Step 4: Recheck After repairing or replacing any components, ensure that you recheck the system to ensure it functions correctly.

1

2

3

4

5


Replacing fuses When replacing a fuse, make sure to use a fuse of the specified capacity. Use of a fuse with a larger capacity will cause a damage to electrical parts and a fire. Disconnecting electrical connectors Before disconnecting or connecting connectors, be sure to do either of the following depending on the type of power supply. Otherwise, the electrical parts to which the power is supplied may be damaged. Continuous power supply: Disconnect the negative cable

from the battery. Ignition power supply: Push engine switch to change the

ignition mode to OFF.

When disconnecting connectors, never pull on the wiring harness (Figure 17). Unlock the connector lock first and then pull the male and female connectors apart by holding them.

When connecting male and female connectors (figure 18), also hold connectors and put them together until they lock securely (a click is heard).

When installing a wiring harness (figure 19), secure it with clamps so that no slack is left.

When installing vehicle parts (figure 20), make sure so that they do not interfere with any wiring harness and they do not catch any wiring harness under them.

Figure 16 Fuse replacement example

Figure 17 Figure 18

Figure 19 Figure 20


Protect the part of harness which may touch any edge by wrapping it with tape or the like (figure 21).

Be careful not to touch the electrical terminals of parts which use microcomputers (e.g. electronic control unit like as ECM, PCM, P/S control module, etc.). The static electricity from your body can damage these parts. (Figure 22)

When taking measurements at electrical connectors using a tester probe, be sure to insert the probe (2) from the wire harness side (backside) of the connector (1)

When it is impossible to insert a tester probe from the

harness side of connector, insert a properly sized male terminal with a lead into the connector and connect the tester probe to the lead as shown. Do not insert the probe directly into the connector, or the female terminal may be deformed.

When checking connection of terminals, check male

terminals for bend, female terminals for excessive opening, and both for locking (looseness), corrosion, dust, etc.

Figure 21

Figure 22

Figure 23

Figure 24


Before measuring voltage at each terminal, make sure that battery voltage is 11 V or higher. Terminal voltage check at low battery voltage will lead to erroneous results

Voltage measurements For voltage measurements, the dial must be adjusted to the Direct Current (DC) Volts function. In this multimeter, a suitable scale must be selected depending on the size of voltage to be measured. As a general rule, when working on the motor vehicle, use the 20 V range because the system voltage is less than 20V. Some digital multimeters have an automatic range function. The voltage function can be used to measure system voltages, supply voltages, voltage drops, etc.

Figure 25 Multimeter (Major Tech, MT21 model shwon) [1] DC Voltage range [2] Insert black probe on COM port and red probe on the VmA port

2

1


If the circuit being checked is under voltage, voltage check can be used to check the circuit. 1) With all connectors connected and voltage applied to the

circuit being checked, measure voltage between each terminal and ground.

a) Example 1 : Open circuit If measurements are taken as shown in the figure 24 and results are as listed below, it means that the circuit is open between terminals B-1 and A-1. Voltage between C-1 and ground: Approx. 5 V B-1 and ground: Approx. 5 V A-1 and ground: 0 V

b) Example 2: High resistance If measurements are as listed below, it means that there is an abnormally high resistance causing the indicated voltage drop in the circuit between terminals A-1 and B-1. Voltage between C-1 and ground: Approx. 5 V B-1 and ground: Approx. 5 V A-1 and ground: Approx. 3 V

Figure 27

Figure 26


Resistance measurements The setting of the multimeter must be used to measure resistance of components and it can also be used to check continuity of wiring. During a resistance test, the digital multimeter uses t internal battery as an electric source therefore do not measure a circuit with has current flowing in it. Before measuring the circuit for continuity or resistance, short circuit the multimeter probes as shown below. The multimeter must display a very low reading, approximately 0 . Interpretation of resistance measurements The following table can be used a guideline to interpreting resistance measurements.

Reading Meaning

OL or 1 No continuity, Infinity

0 Indicates continuity, displays resistance value

1

Figure 28 Digital multimeter (Major Tech, MT21 model shown) [1] Resistance range [2] Insert black probe on the COM port and red probe on the V, ,mA port

2


Example 1) Disconnect negative () cable at battery (figure 27) 2) Disconnect connectors at both ends of the circuit to be checked 3) As illustrated in figure 26, measure resistance between the terminal at one end of the circuit (A-1 terminal in the figure) and ground. If continuity is indicated, it means that the circuit is shorted to ground between terminals A-1 and C-1.

4) Disconnect the connector included in circuit (connector-B) and measure resistance between A-1 and ground. If continuity is indicated, the circuit is shorted to ground between terminals A-1 and B-1.

Figure 26

Figure 26


Current measurements Each electrical load connected to a circuit uses current. As seen in Ohms law, current is directly proportional to the voltage in the circuit. The DC A range is used to measure current being used by each electrical load.

Connection of multimeter and inductive type amp clamp To measure current flowing in a circuit, the current measuring tool e.g. digital multimeter, must be connected in series to the circuit as shown in figure 30 below. An inductive type amp clamp can also be used to measure current without disconnecting the circuit and connecting the multimeter in series to the circuit. Simply clip the clamp around the circuit to or from the load as shown in figure 31. The current flowing to an electrical load is the same as the current that flows out of that electrical load.

Figure 30 Digital multimeter connected in series. [1] Battery [2] Multimeter connected in series

Figure 28 Inductive amp clam type multimeter

1

2

Figure 29 Digital multimeter (Major Tech, MT21 model shown) [1] DC Amps range [2] Insert black probe on the COM port & red probe on the 10A port


Oscilloscope An oscilloscope is a graphic voltmeter. The oscilloscope displays voltage and time as a line on the display screen. An oscilloscope is used to analyze rapidly changing voltage values. Some oscilloscopes can perform multiple measurements at the same time. The SDT (Suzuki Diagnostic Tool) also has an oscilloscope function built-in. Please refer to the course SDT operators manual in GE01 Suzuki Introduction for more details.

Figure 30 Oscilloscope function of the SDT


Summary The alternator and the battery are the main electrical power

sources in the motor vehicle. The electrical circuit in the motor vehicle can be broken

down into power circuit, system circuit and ground circuit. The fusible links in the main fuse box are designed to

protect the entire electrical circuit from excessive current. Relays operate using the principles of electromagnets and

are used to remotely control electrical loads. Small current is used to control large current.

A diode or a resistor is normally used to suppress voltage spikes in voltage suppression relays.

It is important to observe safety precautions when using the digital multimeter to avoid damage to the multimeter and to the vehicles electrical circuit.

When measuring voltage, the multimeter must be connected in parallel.

When measuring current, the multimeter must be connected in series

When measuring resistance, the power supply to the circuit or electrical load must be OFF.

An oscilloscope is a graphic voltmeter that is used when measuring rapidly changing voltage values. These are then displayed in graph form on the oscilloscope display screen.

The SDT has an integrated oscilloscope function. The 4 steps in the electrical circuit diagnosis process are:

Verify, isolate, repair and recheck.


ReferenceElectrical symbols and marks used in Suzuki wiring diagrams


Symbols and marks continued


Electrical symbols and marks continued

Well done, you have now completed the Basic Electrical training course!

sandilemTypewritten Text Please complete the online exam





Basic ElectricalForewordTable of contentsFundamentals of electricityThe Atom, ElectricityCurrent, voltage & resistanceSlide Number 7VoltageDC voltageAC voltage

ResistanceTemperature and ResistanceContact resistanceCircuitsSeries connectionParallel connectionMixed circuits

Internal resistanceEffects of electric currentHeating effectJoule's lawChemical effectMagnetic effectsElectromagnetsMagnetomotive force and electromotive forceElectromotive forceMutual inductionPrinciple of DC motorsPrinciple of AC motor

Electrical circuitsPower sourcesComplete circuitPower distributionMain fuse boxFusesRelaysVoltage spikes

How to read Suzuki wiring diagramsWiring colorsHow to read power supply diagramHow to read system circuit diagramHow to read ground circuit diagramHow to read connector layout diagramConnector codes and terminal numbers

Electric circuit inspectionVoltage measurementsResistance measurementsCurrent measurementsOscilloscope

Electric System Suzuki

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