MODULE 3(1)(2), INTRODUCTION TO ELECTRICAL

Electricity is simply defined as a flow of electric charge.
For a charge to flow, there must be a source, a medium to allow the flow and the user of the charge.
This charges are also referred to as electron which is a component of matter. �Matter is anything that has weight and occupy space. It is composed of tiny particles called atom which is the smallest indivisible part of matter.
Electricity is simply defined as a flow of electric charge.
For a charge to flow, there must be a source, a medium to allow the flow and the user of the charge.
This charges are also referred to as electron which is a component of matter. �Matter is anything that has weight and occupy space. It is composed of tiny particles called atom which is the smallest indivisible part of matter.
Electricity is simply defined as a flow of electric charge.
For a charge to flow, there must be a source, a medium to allow the flow and the user of the charge.
This charges are also referred to as electron which is a component of matter. �Matter is anything that has weight and occupy space. It is composed of tiny particles called atom which is the smallest indivisible part of matter.Electricity is simply defined as a flow of electric charge.
For a charge to flow, there must be a source, a medium to allow the flow and the user of the charge.
This charges are also referred to as electron which is a component of matter. �Matter is anything that has weight and occupy space. It is composed of tiny particles called atom which is the smallest indivisible part of matter.
It consist of 3-sub particles namely�1. Proton (positively charged)� 2. Electron (negatively charged)
3.Neutron (neutral charged)�The proton and the neutron together form the nucleus of the atom with the electron revolving in its orbit held together by the attraction of positively charged nucleus.Depending on arrangement, atoms can gain electron from another atom or lose electron, making them positively / negatively charged.
An electric charge is formed when an electron break loose from its atom. This electron produces electricity when allowed to flow to and fro back to its source when a circuit is placed on it. Theoretically, electron moves from negative to positive but it is conventionally believed that current moves from positive to negative and this is what is widely used.�
INSULATORS : Are materials that inhibit the flow of electrons. It helps to prevent current passing through shorter route and also shield a conductor from interference. E.g plastic, rubber etc.
SEMICONDUCTORS: These are materials that has the ability to control the flow of electricity and are used in building electronics. It has the ability to act as conductor under certain condition and as an insulator in another e.g transistor, diode etc.
Electricity is usually measured by three variables .�1. The amount of currents flowing.�2. Voltage that moves the current �3. the resistance to the flow of electric current.
Current
it is a measure flow

1. MODULE 3 basic automotive electrical

2. objectives At the end of this module, you should be able to: Understand the basics of electricity. Understand the variables and their relationship. Understand the different types of circuits Know how to troubleshoot electrical system.

3. Unit 1 INTRODUCTION TO ELECTRICAL Electricity is simply defined as a flow of electric charge. For a charge to flow, there must be a source, a medium to allow the flow and the user of the charge. This charges are also referred to as electron which is a component of matter. Matter is anything that has weight and occupy space. It is composed of tiny particles called atom which is the smallest indivisible part of matter.

4. It consist of 3-sub particles namely 1. Proton (positively charged) 2. Electron (negatively charged) 3.Neutron (neutral charged) The proton and the neutron together forms the nucleus of the atom with the electron revolving in its orbit held together by the attraction of positively charged nucleus. Depending on arrangement, atoms can gain electron from another atom or lose electron, making them positively / negatively charged.

5. An electric charge is formed when an electron break loose from its atom. This electron produces electricity when allowed to flow to and fro back to its source when a circuit is placed on it. Theoretically, electron moves from negative to positive but it is conventionally believed that current moves from positive to negative and this is what is widely used.

6. Unit 2: cOnductors , insulator s and semiconductors CONDUCTOR : This refers to any material that allows current flow through it. It is used to carry electric current through a circuit. The electrical property of a conductor depends on the number of electron in the outer shell e.g copper.

7. INSULATORS : Are materials that inhibit the flow of electrons. It helps to prevent current passing through shorter route and also shield a conductor from interference. E.g plastic, rubber etc. SEMICONDUCTORS: These are materials that has the ability to control the flow of electricity and are used in building electronics. It has the ability to act as conductor under certain condition and as an insulator in another e.g transistor, diode etc.

8. Revision question 1. What is electricity? 2. Mention 5 types of conductors 3. Mention 5 types of insulators 4. Why is gold not popularly used as a conductor 5. What advantage does silver as a conductor over copper?

9. ELECTRICAL VARIABLES Electricity is usually measured by three variables . 1. The amount of currents flowing. 2. Voltage that moves the current 3. the resistance to the flow of electric current. Current it is a measure of flow of electron in a circuit. Think of current as the flow of water through a pipe. It is measured in ampere (A).Unlike voltage the current does not decrease, it is the same at the beginning to the end of the circuit.

10. VOLTAGE It is regarded as potential energy of electricity. It is the force behind the movement of current in a circuit, referred to as (E.M.F (Electron Moving Force). Think of a voltage as a full tank of water, it does not decrease if the tank is not opened but depletes when opened. It is measured in volts (v).

11. RESISTANCE It is the opposition to the flow of a current in a circuit. Every electrical circuit needs some form of resistance to work. It could be as simple as the conductor and as complex as the load in the circuit. It is measured in ohms ( Ω ).

12. Key electrical notes Voltage is created when an EMF is acting on a conductor. Electron flows only when a voltage difference exist between two points in the conductor The ground of a circuit is regarded as point of lowest voltage and the return path of the circuit. By convention, current flows to ground in an electric circuit. Resistance controls the amount of current passing through it. All resistance changes energy to heat to some extents.

13. OHM’S LAW Ohms law states that the current flowing through a conductor is directly proportional to the voltage across the end of the circuit provided that the variables like temperature are constant. V α I This law establishes the relationship between all electrical variables in that Resistance is the constant.

14. V= R I This simply means if there is an increase in voltage, and resistance remains the same, the current that would flow through the circuit also increase and vice versa. If the resistance of a material increases such as (corrosion build up), the current that passes through the circuit would reduce at constant voltage

15. power It is the rate at which an electrical work is done.

16. If for example the battery on a car (12V) is weak and now has (10V) on it, is used to power a bulb of about 20 Ω . The current that is supposed to flow through the bulb (0.6A) would reduced to (0.5A) and this could result in dim illumination from the bulb.

17. A circuit is a complete path for current when voltage is applied. There are some basic component that makes up a circuit, which are. 1. A power source 2. Protection 3. Conductor 4. Control devices 5. Load Unit 3 CIRCUITS

18. POWER SOURCE:- In automobile the primary power source is typically the battery. It has two heads, the positive and the negative head. The negative head is connected to the car body/chassis and referred to as ground . This means the body/chassis is serving as a return path for the circuit

19. The positive head is connected to the three major places, the starter motor, fuse box and the alternator. It then powers other electrical devices through the fuse box PROTECTION DEVICE:- They are devices used to guard against a damage to electrical device in the advent of electrical surge e.g. Fuses, fusible link and circuit breakers. They protect by opening up the circuit path.

20. CONTROL DEVICES:- They are devices that must be operated before an electrical device would work. The mode operation however is could be through physical activation or dependent on some measured factors e.g. Switch, relays, Transistors and ECUs. LOAD:- The load is any component that uses electricity to do work, e.g. Light, Coil, Horn, Radio etc.

21. TYPES OF CIRCUIT There are 3 types of circuit. 1. SERIES CIRCUIT:- A series circuit consist of two or more electrical loads connected in a way that same current flows through them. FEATURES An open, any where in the circuit affect others. The total resistance is the sum of all the resistance of the loads in the circuit.

22. The source voltage equals the sum of voltage drop across each loads.

23. PARALLEL CIRCUIT:- Parallel circuit has more than one path for current, each path operates independent of the other. FEATURE Total resistance is lower than the resistance of individual load. An open in a path would not affect other circuits . The total current equals the sum of individual current on paths . Voltage is constant through the circuits.

24. SERIESE-PARALLEL CIRCUIT :- This is the combination of the above two circuits. It would consist of a minimum of three loads. FEATURES Total voltages equals the sum of total voltage drop on parallel circuit plus the series circuit component. Total resistance will be equal to total parallel circuit resistance plus individual series circuit resistance. In series-parallel current flow through the series segment and split to flow through the parallel .

25. Circuit issues There are three major faults common to electrical circuits; they are Short circuit Open circuit High resistance SHORT CIRCUIT: this is the term used when an a circuit finds an alternative path different from what it was designed to be. It is not an intended circuit and could result serious electrical issues. It could exist as a short to ground, short to power or any other short aside from the two aforementioned

26. Short to positive Short to positive is similar but in this case involves a contact with a wire that carries positive charge.

27. Open circuit Open circuit: This is a broken circuit which would stop the flow of current across a circuit thereby making the load to be in operative The open could be anywhere in a circuit, it could be on the feed side or ground side of the circuit and as well as in the load. Major suspect on the feed side is the fuse, however an open could also be on the conductor A major culprit on the ground side is a loose ground.

28. High resistance It is caused by the presence of an unwanted resistance in a circuit. These could e due to corrosion build up, loose connections, wrong wire size or breakage of wire strands This is a problem that causes an excessive voltage drop at some point before the load in the circuit or after it. It is different from an open circuit fault in that current still flows in the circuits. An open voltage check might measure source voltage. A voltage drop test is the easiest method of determining high resistance fault

29. Revision question What appropriate fuse rating would be good for a circuit that has two load of 20W and 15W connected in parallel? What is the effect of an open circuit on a circuit? What is the effect of a short to ground on a circuit?

30. Unit 4 Electrical measuring tools A good electrical components most time might not be known through physical appearance, so a there is a need for electrical tools that could measure certain variables to know if the component or connection is right. Tools commonly used for electrical troubleshooting are test lamps, multimeter , scan tools, oscilloscope, cutters, and jumper wire among others.

31. Test lamp this is a good tool to know if the prerequisite for a load to work gets to the load. It consist of a bulb(a low wattage), a probe and a wire connected to a clip. It uses the principle of a closed circuit to determine if positive or negative needed by the load is present at the load. It however restricted to a 12v system as it cannot measure effectively voltage lower than this and does not display the voltage available.

32. How to use a test lamp The following steps describes how to use a test lamp in an electrical diagnosis Test the test lamp operation by placing the probe end and the clip end to a positive and negative respectively to confirm a good circuit on the tester Determine what is to be checked, Study the operation of the faulty circuits and identify its proper operation conditions If it is a positive for example, place the clip end of the test lamp to a negative source (best at negative battery terminal) probe the circuit to be checked one after the other. Any one that lit the bulb after been probed carries a positive. If the bulb does not lit, then check fuses or use wiring diagram to determine circuit path for further troubleshooting.

33. Multimeter this is a meter that could be used for many electrical variable measurement. It comes in analog or digital form Digital are mostly used in automotive repair in that it has a high impedance and draws a little or no current form measuring device thereby reducing the chances of causing a damage to vehicle computers It is powered by a battery and consist of a pair of probe or more in the case of insulation tester It has a Voltmeter that helps to measure voltages of different ranges, ohms meter that is used to determine the resistance of a material, a continuity function that helps determine the integrity of a conductor ammeter which helps to measure current through a circuit etc

34. MULTIMETER

35. Feature of a multimeter A simple multimeter consist of A jack A dial Function button probe

36. jACK This is the hole that the probes are fixed on The number of jacks depends on the manufacturer. It could 2, 3 0r 4 Each of the jack are labelled with the parameter it is used to measure The com jack is where the black probe Other possible jack are the v/ohms, milliamp, amp and insulation. Careful selection of the jack is necessary for correct reading and to avoid a damage to the meter.

37. Dial It is used to select the necessary parameter to be measured, they are Voltmeter: it is a function used to measure the voltage potential of at any point in a circuit or passing through a conductor. It is denoted with a V with a straight line on it denoting DC voltage or with a sinusoidal line denoting AC voltage.

38. Ohms meter It is used to measure the resistance of a circuit or component. It allows for comparism with manufacturer’s specific resistance. The device being tested should be powered down to have an accurate reading.

39. amperage This is used to measure of the amount current passing through a circuit. It is connected in series to a circuit except in a case of inductive amp probe. It could be measured in either AC current or DC just like voltage. Careful selection of range is important before connection.

40. Continuity and diode Used to know the integrity of a conductor It buzzes when the probe is used on the two ends of a good conductor Diode function is used to test the integrity of a diode.

41. Function buttons Most multimeters have buttons on them that is meant to switch certain functions on the meter, they are On/off Auto range/range selection Min/max Insulation test Hold

42. Jumper cable It is used to bypass a side or both side of a circuits. It is usually fused and the type used on a circuit should depend on the amps rating of the device. The proper wire nomenclature should be known before jumping

43. Scan tools Scan tool is a tool used to interact with vehicle computers It is a bidirectional tools that could send and receive information from vehicle computers it fixes on to the car through the Data link connector. Most are not self powered, hence are powered through the dlc . A typical dlc port would consist of battery positive, ground and at least a communication line

44. A typical OBD2 dlc consist of 16 pins Pin 4 is chassis ground, 5 is signal ground and 16 is battery positive Other pins represent a communication line or manufacturers digression.

45. oscilloscope

46. Unit 5 Electrical troubleshooting When an electrical faults happens, certain processes is needed to be followed to get to know trouble area and solution to the problem. Before proceeding on electrical troubleshooting, it is necessary to examine the source of electricity i.e the Battery and the charging system.

47. Battery Battery is an electromechanical device that uses chemical energy( sponge lead, lead oxide and sulfuric acid react chemically) to electrical energy (allows the flows of current) This is the primary source of electrical power, it helps to power up electrical devices when engine is not running, filter off ripples from the charging system there by making a neat dc voltage available for the load it also support the charging system at low engine speed when electrical demand is high.

48. Battery testing There are three different methods of testing the battery State of charge of the battery Performance of the battery Physical appearance STATE OF CHARGE: this could be tested using hydrometer to check for the specific gravity of the electrolyte, a charge indicator on the battery or checking for the open circuit voltage of the battery using a multimeter .

49. the hydrometer test can not be used on sealed and maintenance free battery while the charge indicator type shows the condition of just one of the cells of the battery. Open circuit voltage State of charge 12.6V 100% 12.4V 75% 12.2V 50% 12.0V 25% 11.8V 0%

50. Open Circuit Voltage (OCV) Test  An OCV test may be performed with a multi meter. To determine the voltage on the battery, turn off all electrical loads on the car.  Put on the full light for 30seconds to remove surface charge.  Select the dc volt function and a 20V range on 12V system or 40V range on a 24V system. Connect the probes to the positive and negative terminals and measure the terminal post voltage with no loads on.  Allow the reading to stabilize and compare the value on the meter to the table above.

51. Open circuit voltage

52. Performance Load Test: This helps to determine if a battery can or can no longer hold charge. It is a more accurate way to test the health of the battery. A load tester is used and this help places a load on the battery and see if the battery could hold charge.

53. Physical checks Visually check the battery and observe Foul smell Broken terminal Bulge or bump in the case Crack or rupture on the battery case Excessive fluid leak These are tell tale signs of a bad battery.

54. charging system The electrical and electronic devices of an automobile require a source of power for operation. Typically, the battery provides power to keep these components running but without charging the battery it will run down within a short time. The charging system charges the battery when the engine is running and also supplies power to the vehicle components. The system consists of the following: Charge indicator (battery light on the dashboard or instrument cluster): used for warning the driver/vehicle operator of a charging system problem (poor charge or no charge). Alternator: an ac voltage generator that has an inbuilt rectifier (converts ac voltage to dc voltage) and regulator . Battery: an electrical storage for electrical power or energy.

55. Charging system test The charging system test is mainly used to know the health of the charging system Get a functional multi meter and set it on a dc voltage range a bit higher than the operating voltage on a vehicle (14V) Put on the multi meter and fix the probes to the appropriate port on the meter and fix the red probe on the positive terminal and the negative probe on the negative terminal Check the voltage reading on the battery Start the car and allow the rpm of the car to drop below 1000 Check reading on meter and note it Put on the electrical loads on the car Observe the voltage reading once more

56. For a good charging system, the expected value 0.5v above battery voltage and about 2V above. A n undercharging system results with a voltage below 13.2.

57. Diagnostic steps Skills, know-how of how system works and logical reasoning is needed to successfully fix .the problem. A general fault finding step should also be deployed. they are Verify the complaint: verify the complaint of the vehicle’s operator by operating the system or taking a test drive to see if the complaint is really a problem.

58. 2. Determine the symptoms: check for the symptoms of the complaint and observe abnormalities in the vehicle’s operation. 3. Analyze the symptoms: all abnormalities should be well looked into for causes of such abnormal operation. 4. Isolate the troubled area: good analyses of a system can lead a technician to the affected area of the vehicle. When discovered, isolate the area and work on it. 5. Correct the trouble: the real fault in a troubled area can range from a faulty and/or worn-out part/s, poor adjustment or a bad circuitry to a particular component. This should be corrected or repaired. 6. Check for proper operation: after repairing a fault, the system should be tested properly for efficient operation

59. task Record a video showing you doing a charging system test on a car. record a video showing you checking the fuses 0n a car using either a test lamp or multi meter.