Automotive Electrical-Electronics Level-I PDF

Automotive Electrical-Electronics Level-I Apply Automotive Electrical System Fundamentals PREPARED BY:-FUAD.I  Unit one Identify and locate Electrical /electronic fundamentals Atomic Structure  An atom is the smallest part of...

Automotive Electrical-Electronics Level-I Apply Automotive Electrical System Fundamentals PREPARED BY:-FUAD.I  Unit one Identify and locate Electrical /electronic fundamentals Atomic Structure  An atom is the smallest part of a chemical element that still has all the characteristics of that element.  Atoms attempt to have the same number of electrons as there are protons in the nucleus.  A specific number of electrons are in each of the electron orbit paths. The outer orbit, or shell as it is sometimes called, is referred to as the valence ring.  For example, a copper atom contains 29 Electrons; 2 in the first orbit, 8 in the second, 18 in the third orbit, and 1 in the fourth  Electron Flow The number of electrons in the outer orbit (valence shell or ring) determines the atom's ability to conduct electricity. Electrons in the inner rings are closer to the core, strongly attracted to the protons, and are called bound electrons. Electrons can be freed by forces such as friction, heat, light, pressure, chemical action, or magnetic action. These freed electrons move away from one atom to the next. A stream of free electrons forms an electrical current. To have a continuous flow of electricity, three things must be present: An excess of electrons in one place, A lack of electrons in another place & A path between the two places.  Current Flow Theories There are two theories describe current flow.  The conventional theory: commonly used for automotive systems, says current flows from (+) to (-).  The electron theory: commonly used for electronics, says current flows from (-) to (+). While the direction of current flow makes a difference in the operation of some devices, such as diodes, the direction makes no difference to the three measurable units of electricity: voltage, current, and resistance   The three most commonly used instruments for measuring DC circuit values are: 1. Ammeter (a device for measuring current) 2. Voltmeter (a device for measuring voltage) and 3. Ohmmeter (a device for measuring resistance) Ammeter One of the problems with electricity is that we cannot see it. We have to rely on instruments to detect its presence, and to measure it. To measure current we need a "flow" meter  b. Voltmeter When current flows through a resistance some of the supply pressure (voltage) is lost across that resistance. There is a pressure difference across the resistance. Therefore a voltage difference is found across components. To measure it the voltmeter has to be connected across the component (i.e. in parallel with it).  C. Ohmmeter When measuring resistance the ohmmeter provides the voltage to pass a current through the components. From the current flowing, the meter works out the resistance. It is therefore important that there are no other currents flowing. The component to be measured must therefore be  Current Electric current is a flow of electrons and is measured in amps, (short for amperes). The amp is a measure of flow rate. In other words how much electricity is flowing per second. 1 amp = 6,240,000,000,000,000,000 electrons per second In electronic circuits a current of one amp is quite large, so often the milli-amp is used instead. A milli-amp (mA) is a thousandth of an amp (A).  Voltage Electricity does not flow through a wire unless it is pushed. There has to be an electrical pressure and this pressure is called voltage and is measured in volts. The symbol is V. It is also called electrical pressure, and electromotive force (emf). This pressure can be provided by a battery, or it can be produced by a generator. Resistance The rate that the electrons pass around the circuit (i.e. the amount of current) is dependent not only on the force (voltage) but also by how much resistance there is in the circuit. Resistance is measured in ohms (W). If the same voltage is used in a low resistance circuit as in a high resistance circuit, more current (amps) will flow in the low resistance circuit. Because in a car the same 12V battery powers all circuits, the only way that current can vary is by varying the resistance.  Ohm's Law In 1827, George ohm introduced simple mathematical formula, which relates voltage, current, and resistance. This formula is called ohm's law. Ohm's law says voltage is equal to current time’s resistance. A force of 1V is required to push a current of 1A through a resistance of 1W.  Sources of electricity There are several different devices that can supply the voltage necessary to generate an electric current The two most common sources are generators and electrolytic cells. Generator Generators use mechanical energy, such as water pouring through a dam or the motion of a turbine driven by steam, to produce electricity. The electric outlets on the walls of homes and other buildings, from which electricity to operate e lights and appliances is drawn are connected to generators located in electric power stations. The voltage between the terminals drives an electric current through the appliance that is plugged into the outlet.  Electrolytic cells Electrolytic cells use chemical energy to produce electricity. Chemical reactions within an electrolyte tic cell produce a potential difference between the cell’s terminals. An electric battery consists of a cell or group of cells connected together. Other sources There are many sources of electric current other than generators and electrolytic cells. Fuel cells produce electricity through chemical reactions, fuel cells do not store chemicals and therefore must be constantly refilled. Electricity produced directly by heating is called thermoelectricity. Some substances emit electrons when they are struck by light, Electricity produced in this way is called photo electricity. When pressure is applied to certain crystals, a potential difference Develops across them. Electricity thus produced is called piezoelectricity. The piezoelectric effect occurs in crystalline  Electronic component system Passive electronic components Passive components do not have gain or directionality. In the perspective of electrical technology, Passive components are known as electrical components or elements. Passive components are capacitors, inductors, resistors and diodes. Active electronic components Active components have their own gain or directionality. Semiconductor devices (various Types of transistors) and vacuum tubes come under active components.   Multi-meter Most meters used for measuring DC circuit values by technicians are multipurpose meters or multi-meters. They are generally designed to measure voltage, resistance, and current. Therefore, a multi-meter is often called a volt-ohm-ampere-ammeter, or VOM, because it can measure volts, ohms, and amperes.  A multimeter can be one of two types: 1. Analog - display uses a needle to point to a measured value on a scale. 2. Digital - display shows measured value in actual numbers (digits).  1. Analog Multimeters Analog meters use a mechanical movement and are not suitable for measurements in circuits with sensitive electronic components.  Use a mechanical movement to drive a pointer.  Display a measured value where the pointer intersects a calibrated scale.  Are not suitable for measurements in circuits with sensitive electronic components (such as ECUs).  Are more susceptible to damage from mechanical shock than are digital multimeters.  2. Digital Multimeters Digital multimeters display the actual measured value and are suitable for measurements in circuits with sensitive electronic components.  Use a digital display.  Display a measured value in actual numbers.  Are suitable for measurements in circuits with sensitive electronic components (such as ECUs).  Are less susceptible to damage from mechanical shock than are analog multimeters.  Have a longer battery life.  Have a higher internal resistance. The main components found on the front panel of a typical digital Multimeter (DMM) are …  Digital display  Range selector  Mode selector  Input jacks This figure shows the main components of a typical digital Multimeter. The mode selector knob lets you set the meter for the type of test you want to perform Use the mode selector to set the meter for the type of test to be performed. These are the modes available on a Fluke 87 DMM:  Off - Turns the meter off. Turning the mode selector to any other setting turns the meter on.  Volts AC - Use to measure voltage in alternating current (AC) circuits.  Volts DC - Use to measure voltage in direct current (DC) circuits.  Millivolts DC (mV) DC - Use to measure very low voltage in direct current (DC) circuits.  Resistance/Continuity (ohms) - Use to measure resistance and check continuity.  Diode Check - Use to check the operation of a diode (meter sendsa small current through the diode).  Amps or Milliamps AC/DC - Use to measure current in a circuit.  Microamps (AC/DC) - Use to measure very small current in a circuit.  Test Light A test light, test lamp, voltage tester, or mains tester is a piece of electronic test equipment used to determine the presence of electricity in a piece of equipment under test.  Soldering Equipment A. Soldering iron: A soldering iron is a hand tool used in soldering. It supplies heat to melt solder so that it can flow into the joint between two work pieces. A soldering iron is composed of a heated metal tip and an insulated handle. Soldering Gun: A soldering gun is an approximately pistol- shaped, electrically powered tool for soldering metals using tin- based solder to achieve a strong mechanical bond with good electrical contact.  Diagonal Cutters Diagonal cutters often used for cutting the end of cable ties flush to cutting wire. Wire Crimpers A crimping tool is any tool that is designed to “crimp” a connector onto the end of a length of wire.   AC Circuit A circuit containing an AC supply source of voltage is known as AC circuits. The supply sources for example are alternator and synchronous generators.  DC Circuit A circuit containing a DC supply source of voltage is known as DC circuits. The supply sources for example are batteries and DC generators.   Integrated circuits An integrated circuit (ICs) is an electronic device comprising numerousfunctional elements such as transistors, resistors, condensers, etc. on a piece of silicon semiconductor substrate, and is sealed inside a package with multiple terminals.  UNIT TWO Determine Electric Circuit System  Electrical test equipment Various electrical tests and testing devices are used by an automotive technician Jumper Wire  Handy for testing switches, relays, solenoids, wires, and other components  Jumper can be substituted for a component such as a switch If the circuit begins to function with the jumper in place, the component being bypassed is defective Test Light Used to quickly check a circuit for power To use a test light:  connect the alligator clip to ground  touch the pointed tip to the test point in the circuit  if power is present, the light will illuminate Self-Powered Test Light  Used to check for a complete electrical path  To use a self-powered test light:  disconnect the circuit power source  connect the test light leads across the desired part of the circuit  if the light illuminates, the circuit or part has continuity Voltmeter, Ammeter, Ohmmeter and Multi-meter are also electrical tests and testing devices used by an automotive technician.  Types of electrical circuits and ohms laws Circuit is a complete path that electrons travel from a power source (such as a battery) through a load such as a light bulb and back to the power source.  The current must start and finish at the same place (power source). in five basic parts Most automotive circuits contain. 1. Power source - such as a generator or battery. 2. Conductors - wires that provide a path for current flow and insulators - keep electricity in the conductors and load 3. load - a device that changes the electrical energy to usable form of energy such as mechanical, light, sound, magnetism or heat. 4. Controllers - such as switches or relays, that control or direct the flow of electrons 5. Circuit protection – devices such as fuses and circuit breakers  Series circuits In a series circuit, there is only one current path. The same battery current flows through Each component. A breakage in the path would Cease the function of all the equipment's The total resistance in a series circuit is the sum of the individual resistors. This is written as: R =R+R+R total 1 2 3 Electrical loads or resistance connected in series Behave following series circuit laws. LAW 1 The total resistance in a series circuit is the sum total of the individual resistances. LAW 2 The current is the same throughout the entire circuit. LAW 3 Although the current (in amperes) is constant, the voltage drops across each resistance in the ci Parallel circuits In a parallel circuit, there is more than one current path. The current splits up, with the greater current flowing through the smallest resistance. A breakage in any one path would not interfere with the operation of the remainder of the units in the circuit. The total resistance in a parallel circuit is found by using the formula: A typical parallel circuit used in vehicles includes many of the interior and exterior lights LAW 1 :The total resistance of a parallel circuit is always less than that of the smallest-resistance leg. LAW 2 :The voltage is the same for each leg of a parallel circuit. LAW 3 :The sum of the individual currents in each leg will equal the total current. Series-parallel circuits. A circuit is an endless path formed by a conductor from a source of electrical supply to the control, through the load, and back to the source. There are various types of electrical circuits used in the modern automobile, among them the series, and parallel circuits  Most common electrical circuit problems Open Circuits An open circuit is any circuit that is not complete, or that lacks continuity, such as a broken wire, therefore no current can flow.  Short Circuit A short circuit: Is a complete circuit in Which the current bypasses some or all of the resistance in the circuit. Involves the power side of the circuit. Involves a copper-to-copper connection. Is also called a short-to-voltage. May or may not blow a fuse. A fuse or circuit breaker opens the circuit to prevent possible overheating damage in the event of a short circuit. High Resistance circuit High resistance can be caused by any of the following: Corroded connections Loose terminals in a connector Loose ground connection  UNIT THREE Carry out Test and measurements of electrical/electronic systems Test and measurements of electrical/electronic systems components Requirements of Workplace Health and Safety (WHS) Work shop Safety  Floors and work areas should be kept clean and organized.  Keep all tools and equipment clean, dressed, and organized.  Memorize the location of all safety and first aid equipment  Deactivate the high voltage system before any service is performed.  Follow all manufacturer’s warnings and procedures.  Personal Safety  Wear appropriate clothes, shoe...  Ensure the work shop hazard free  The vehicle must park on straight surface  The area must be clean Precautions:-  Ensure work area hazard free.  Keep yourself from electric shock  Keep yourself from danger & injury workings. may be the safety &hydraulic jack will be slept by it self  know and implement the correct procedures  apply wearing of protective cloths  Testing electrical/electronic system and components Electronic system components In electronic systems, the components are solid state and do not have moving parts Solid state circuits use semiconductors Semiconductor  Substance capable of acting as both a conductor and an insulator  this enables semiconductor devices to control current without mechanical points  Semiconductor devices include:  Diodes  transistors  integrated circuits  Diodes An “electronic check valve” that allows current to flow in only one direction  when a diode is forward biased, it acts as a conductor  when a diode is reverse biased, it acts as an insulator  Transistor Allows the control of a high current circuit with a low current circuit  performs the same basic function as a relay  Acts as a remote switch or current amplifier  Operates more quickly than a mechanical device can  Has no moving parts to wear or deteriorate  Transistor Operation  Small base current energizes the semiconductor material, changing it from an insulator to a conductor  Higher current can pass through the collector and emitter terminals  Capacitors  Devices used to absorb unwanted electrical pulses, such as voltage fluctuations  Used in various types of electrical and electronic circuits  Connected to the supply wires for the car radio Circuit tester Using Jumper Cable is used to check (diagnose) a circuit by bypassing The switch or to provide a power Using Test lamp checking fuse, Used to quickly check a circuit for power To use a test light:  Connect the alligator clip to ground  Touch the pointed tip to the test point in the circuit, if power is present, the light will illuminate Self-Powered Test Light Used to check for a complete electrical path To use a self- powered test light:  Disconnect the circuit power source  Connect the test light leads across the desired part of the circuit  If the light illuminates, the circuit or part has continuity   Circuit Protective Devices Fuses: There are three basic types of fuses in use automotive: cartridge, blade, and ceramic. The cartridge fuse is found on older domestic cars and a few imports. Late-model domestic vehicles and many imports use blade or spade fuses. The ceramic fuse was used on many European imports. The core is a ceramic insulator with a conductive metal strip along one side. Fuse Links: Fuse or fusible links are used in circuits when limiting the maximum current is not extremely critical. They are often installed in the positive battery lead to the ignition switch and other circuits that have power with the key off. Fusible links are normally found in the engine compartment near the battery. Fusible links are also used when it would be awkward to run wiring from the battery to the fuse panel and back to the load. Relays: A relay is an electric switch that allows a small amount of current to control a high-current circuit.  When the control circuit switch is open, no current flows to the coil of the relay, so the windings are de-energized.  When the switch is closed, the coil is energized, turning the soft iron core into an electromagnet and drawing the armature down.  This closes the power circuit contacts, connecting power to the load circuit   Vehicle lighting systems The lighting system of a motor vehicle consists of lighting and signalling devices mounted or integrated at the front, rear, sides, and in some cases the top of a motor vehicle. They illuminate the roadway ahead for the driver and increase the vehicle's visibility, allowing other drivers and pedestrians to see its presence, position, size, and direction of travel, and its driver's intentions. The lighting systems can categorizes in to two ways Exterior lights:-lights which are found out of the vehicle. Such as  Head light  Tail light  Parking light  Number plate light. Etc Interior light: - these lights are found the interior part of the vehicle.  Instrument panel light  Luggage compartment light  Hood panel light, Courtesy light. Etc.  Vehicle Instrumentation Systems  Vehicle instrumentation systems monitor the various vehicle operating systems and provide information to the driver about their correct operation.  Warning devices also provide information to the driver; however, they are usually associated with an audible signal. Some vehicles use a voice module to alert the driver to certain conditions.  1. Body Electrical The body electrical components consist of electrical parts that are attached to the vehicle body 1. Wire harness 2. Switches and relays 3. Lighting system 4. Combination meter and gauges