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Chapter 51Electrical Components and WiringNATEF TasksN51001 Use wiring diagrams during the diagnosis (troubleshooting) of electrical/electronic circuit problems. (AST/MAST)N51002 Use wiring diagrams to trace electrical/electronic circuits. (MLR)N51003 Inspect, test, repair, and/or replace components, connectors, terminals, harnesses, and wiring in electrical/electronic systems (including solder repairs); determine needed action. (MLR/AST/MAST)N51004 Repair data bus wiring harness. (MAST)Knowledge ObjectivesAfter reading this chapter, you will be able to:K51001 Describe the function and purpose of electronic components.K51002 Describe wires and wire harnesses.K51003 Repair wiring harness.Skills ObjectivesThere are no Skills Objectives for this chapter.Readings and PreparationReview all instructional materials, including the chapter in Fundamentals of Automotive Technology: Principles and Practice, 2e, and all related presentation support materials.Support MaterialsLecture PowerPoint presentation including all Skill DrillsPre-LectureYou Are the Automotive TechnicianA progressive case study that encourages critical thinking skills.Direct students to read the “You Are the Automotive Technician” scenario found at the beginning of each chapter.Group Activity: Direct students to review the discussion questions at the end of the scenario and prepare a response to each question. Facilitate a class discussion centered on the questions.Homework Assignment: Ask students to turn in their comments on the questions.Teaching Tip: Explain to students how this material applies to the workplace. Provide an example of situation to make it relevant and meaningful. How does it fit into the broader picture? Is it building on something they already know? Will it help them master a skill? Students need to understand that what we are teaching is of importance on the job. This is especially critical in the soft skills areas. That is an area where students need to know that their future boss is going to expect them to communicate like a reasonable adult and show up on time.Lecture IntroductionElectrical components are used in a circuit to modify or manage the flow of currentTerminals are often numbered or marked with the connectionsElectrical components are connected together by wires in wire harnessesCircuits carry electrical signals and commands that are used in virtually every system on the vehicle Electrical ComponentsSwitchesA switch is an electrical device used to turn the current on and off in a circuitWhen turned off, switches open the circuit, stopping current flow; when turned on, they close the circuit, allowing current to flowThere are many different types and configurations of switches, including toggle switches, push-button switches, and specialty switchesA turn signal switch has three positions: center for off, moved down for the left turn signals, moved up for the right turn signalsCircuit or schematic diagrams typically show switches, their contacts, and the surrounding circuitsCircuit Protection DevicesFuses and circuit breakers are designed to protect electrical circuits by opening the circuit if the current flow is excessiveMost common kinds of circuit protection devices are fuses, fusible links, circuit breakers, and positive temperature coefficient (PTC) thermistor protection devicesFuses and circuit breakers are rated in ampsFuses come in a variety of configurations, from cylindrical glass cartridge fuses to plastic blade fusesBlade fuses also come in a variety of physical sizes including micro, mini, regular, and maxiFusible links are typically placed near the battery to protect the wiring harness between the battery and any fuse boxesCircuit breakers are not destroyed by excess current and can be reset, either automatically or manuallyPTC thermistors have very low resistance at room temperature, but increase in resistance as the temperature increasesPTCs generally reset once power is removed and they are allowed to coolFlasher Can/ControlThe flasher can is the control mechanism for the turn signal lights on the vehicleFlasher cans are mechanical devices whereas flasher controls are generally electronic devicesFlasher cans use a bimetallic strip to open and close the switch contactsElectronic flasher controls control the on/off function electronicallyIn newer vehicles, the flasher operation is activated by the body control moduleRelaysSwitches that are turned on and off by a small electrical currentIdeal for using a small current to control a larger currentMade up of an electromagnet, a set of switch contacts, terminals, and the caseUsually consist of three contacts: two fixed and one movableThe movable contact is fixed to a spring-loaded armature blade and held against one of the fixed contacts, which is called the normally closed (NC) contactWhen the relay coil is activated, the electromagnet pulls the movable armature blade contact away from the NC contact and against the normally open (NO) contactWhen the contact points are closed, current flows across the contact points and out through the electrical device to the rest of the circuitA solid-state relay acts like a mechanical relay but does not have any moving partsAutomotive relay terminals use one of two standard labeling systems: 85, 86, 30, 87a, and 87 or 1, 2, 3, 4, 5SolenoidsAn electromechanical device that coverts electrical energy into mechanical linear (back-and-forth) movementIn a simple solenoid, insulated wire is wound many times around a hollow tubeSolenoid design may incorporate return springs, multiple windings, electrical contacts, and mechanical connectionsFuel injectors and starter motor solenoids are two of the many solenoid-type components used in a motor vehicleA solenoid uses a magnetic field to create lateral movementThe metal core used by the electromagnet to strengthen the magnetic field is referred to as an armatureAnother device that uses a solenoid is a vehicle hornMotorsElectric motors use magnetic fields to create rotary movementMotors consist of two main components: the armature and the fieldThe armature contains electromagnetic coilsThe field contains either electromagnets or permanent magnetsThe interaction between the magnetic fields of the stationary field coils and the magnetic fields of the moveable armature coils causes the armature to rotateCommutator is a segmented component of the armatureThe commutator and brushes act as switches to control the current flow through the windings of the armatureIgnition Coils and TransformersOperate under the principles of electromagnetic inductionAn ignition coil can be described as a step-up transformerA primary winding is wound around a secondary windingThe primary coil typically has 200 to 300 turns of light-gauge wire and the secondary has approximately 30,000 to 60,000 turns of very fine wireTransformer action causes heat to be producedIn step-down transformers, the secondary coil has fewer turns than the primaryStep-down transformers provide a lower induced outputResistorsElectrical components that resist a current running through themA resistor in a circuit causes a drop in voltage across the resistor and also reduces the amperage in the circuitEach electrical component has its own resistanceMost high-wattage resistors contain a coil of high-resistance wire wound around a ceramic form to dissipate heatFixed ResistorA cylinder with connecting metal leads projecting along the axis of the cylinder at each endMost axial resistors are marked with a series of colored stripes to indicate their resistance and tolerance levelsFixed resistors can be built into integrated circuits with many other miniaturized componentsVariable ResistorsThe value of variable resistors can be altered by movement of a slide or by temperature changeThe three types of variable resistors are rheostats, potentiometers, and thermistorsVariable resistors can be linear or nonlinearRheostatsMechanical variable resistors with two connectionsConsist of a resistance wire wrapped in a loose coil connected to the supply at one end onlyA moveable wiper is connected to the other circuit connection and is made to move over the wire manuallyRheostats are commonly used in dash light dimmer circuits and some fuel gauge sender unitsPotentiometersMechanical variable resistors with three connections, two fixed and one moveableAct as voltage dividers and as such alter the voltage in a circuitA resistance wire is wrapped between two fixed connectionsThrottle position sensors are potentiometersThermistorsThermistors are conductors in which resistance value is affected by temperatureTwo types: negative temperature coefficient (NTC) and positive temperature coefficient (PTC)The resistance value of NTC thermistors is altered inversely to temperatureIn PTC thermistors, resistance value alters proportionally to temperatureResistor RatingsResistance is measured in ohms, ΩResistors are rated in ohms as well, to indicate how strongly they will oppose any current flowing through themThe resistor’s power rating is determined by its sizeTo identify their value, many resistors are marked with four or five colored bandsEach color represents a numeric resistance valueThe color bands are set close to each other and read from left to rightThe last band is the tolerance bandCapacitorsCan quickly store a small amount of electrical energyUsed for several purposes: voltage suppression and in delay circuits for timing purposesWhen the capacitor is charged, one surface is positively charged and the other is negatively chargedA capacitor’s capacitance (C) is a measure of the amount of charge (Q) stored on each plate for a given potential difference or voltage (V) that appears between the platesThe voltage rating of the capacitor is directly proportional to its physical size Electronic ComponentsK51001 Describe the function and purpose of electronic components.Electric components have no moving parts, such as diodes, transistors, and integrated circuitsEach component has a particular function and, when arranged in circuits, interacts with other components to control electrical and electronic functionsIndividual components may be mounted in a housing to operate as a sensorMany components can be arranged in circuits and mounted on circuit boards to perform various functionsSemiconductorsElectronics usually refers to devices in which electrons are conducted through a vacuum, gas, or semiconductorSemiconductors are very versatile substances and are widely used to make various electronic componentsA semiconductor’s electrical material has exactly four electrons in its valance ringA semiconductor’s conducting ability depends on two kinds of charge carriers:The negative electronThe holeThe number of charge carriers can be altered by dopingDoping adds very small quantities of impurities to a semiconductor materialN-type semiconductors have excess electronsP-type semiconductors have excess holesSilicon is the most widely used semiconductor material because it has a useful temperature range and is abundant, cheap, and easy to manufactureGermanium was among the first semiconductor materials to be developedHigh-speed semiconductors widely use gallium-arsenideSilicon carbide has been used to create blue light-emitting diodesSemiconductor OperationP–N junction is the point where P-type and N-type semiconductors joinIn a depletion layer, some electrons and holes cancel each other out and few charge carriers are presentThe P–N junction creates a depletion area that changes its charge carrying ability based on polarityA diode is one P-type semiconductor material joined to one N-type materialA Zener diode is designed to block current flow through it, but if the voltage is large enough, it can force current to flow through the diodeAs breakdown voltage is reached, the Zener diode’s resistance suddenly collapsesTransistorsSemiconductor devices used as a switch and to amplify currentsMade up of three sections of semiconductor materials: two of one polarity and one of the opposite polarityThe NP–N transistor has a P-type semiconductor between two N-type semiconductorsA P–NP transistor has an N-type semiconductor between two P-typesOn a bipolar transistor, the center region is always called the base; the outer regions are the collector and the emitterIn a circuit, transistors can act as an electronic switchIn the case of an NP–N transistor, positive current through a resistor is applied to the baseIn a P–NP transistor, a ground is applied to the baseControl ModulesAn electronic unit that controls one or more electrical systems in the vehicleMonitor a number of inputs from sensors and circuits, process those data, and send output commandsA data bus is a common set of wires that connect the modules together so that information or data can be shared across the networkMicroprocessors, Sensors, and Voltage-Generating DevicesProgrammable devicesMicroprocessors control and monitor most electrical systems on the modern vehicleModern diagnostic equipment connects into the microprocessors on the vehicle via a data link connectorMicroprocessors require programming updatesMany different types of sensors are installed into the modern vehicle and are used to provide information to the microprocessors on the vehicleA sensor essentially converts a mechanical action into electrical signals that can be read by the microprocessorsDelay CircuitsAdded to vehicles to build in specific time delays in turning electrical devices on or offCan be constructed from electronic components, or it can be programmed into an ECU that controls the circuitModern vehicles are increasingly using ECUs with programmed timers to perform time-delay functionsSpeed Control CircuitsUsed on the vehicle to control the speed of motors or accessoriesOne common use is to control the fan speed in the vehicle’s HVAC system and the electric radiator fanMost speed control systems use a form of pulse width modulationDuty cycle refers to the percentage of time a circuit is fully on versus fully offSpeed control circuits are constructed from electronic components that can be in dedicated modulesPrinted/Integrated CircuitsInsulated boards designed to hold electronic components such as microprocessors and their associated componentsConductive tracks on the surface of the printed circuits connect the leads of the electronic components to each other to form complex circuitsMany boards have more than one layer of conductive tracks Wires and Wiring HarnessesK51002 Describe wires and wire harnesses.Need to be kept in good condition, free of any damage or corrosionCarry the electrical power and signals through the vehicleAlthough wireless communication is being used nowadays, wires are still the dominant signal carriers in a vehicleTo keep the wires organized, they are bundled together in a wiring harnessWiresUsed to conduct current around the vehicleCommonly a multi-stranded copper core wrapped with seamless plastic insulationCopper offers low electrical resistance and remains flexible even after years of useRibbon cable is a series of wires that are formed side by side and joined along the wire insulationRibbon cable is often found inside computers and other electronic componentsWire SizesWire size is very important for the correct operation of electrical circuitsThe diameter of a wire affects its resistance and therefore how much current it can carryThe resistance of a wire is determined by its length, diameter, construction material, and temperatureTwo scales are used to measure the sizes of wires: the metric wire gauge and the American wire gauge (AWG)The metric wire gauge measures the cross-sectional area of the conductor in square millimetersThe AWG system uses a rating number; the larger the rating number, the smaller the wire and the lower its current-carrying capabilitySome American manufacturers use AWG, while others use the metric scaleThe correct wire size for an application can be looked up on a wire size chartTerminals and ConnectorsTerminals are installed to the ends of wires to provide low-resistance terminationThey allow electricity to be conducted from the end of one wire to the end of another wireDifferent types and sizes: push-on spade terminals, eye ring terminals to accommodate screws, butt connectors, and male and female terminalsSolder-type terminals require the use of electric or gas soldering irons, flux, and solder to make the connectionTerminals can be installed as a single terminal on a wire or grouped together in a wiring harness with a connector housing, also called wiring harness connectorsConnector housings have male and female sides and are usually shaped so that they can be connected in only one wayWiring HarnessesUsed to group two or more wires together within a sheath of either insulating tape or tubingRun around the engine bay, through the dash and interior cabin, and to the rear of the vehicleAttached to the vehicle with harness fasteners such as body clips or wire ties, and rubber sealing grommetsShieldingWiring harnesses are subject to a situation where unwanted electromagnetic induction occursTo prevent electrical noise or EMI noise, many vehicles use shielded wiring harnessesThe type of shielding used can be one of three forms: twisted pair, Mylar tape, or drain linesTwisted PairUses two wires delivering signals between common componentsThe twisted wires, along with the terminating resistor, have the effect of canceling any noise that occurs in the wiresThe controlled area network bus, or CANbus, in a modern vehicle may use one or more twisted pairs to connect all the vehicle control units with a common data lineMylar TapeAn electrically conductive material that is wrapped around a wiring harness inside the outer harness layerShielding is important to prevent electrical noise penetrating into the electrical wiringIf the harness is exposed, the Mylar will have to be rewrapped so that noise cannot penetrate into the harnessDrain LinesA drain line is a non-insulated wire that is wrapped within a wiring harnessConnected to ground at the harness source end and conducts any noise to ground, negating the noise effectNetworking and MultiplexingSensors integrated into a common wiring harness by combining many of the individual systemsA controlled area network bus (CANbus) uses two thin wires to connect or multiplex many of the control units and their sensors to each otherA multiplex network enables a decreased number of dedicated wires for each functionNetworking makes it more efficient to add or modify system functionality through the addition of control units and the use of software updatesA diagnostic scan tool can be connected to the CANbus circuit to both extract operational information and command controlled devicesFiber OpticsLong, thin strands of very pure glass or plastic about the diameter of a human hairCan be arranged in bundles, called optical cablesLight is transmitted along the cable, bouncing from wall to wall along the way as it is transmitted through the cableOptical fiber can be used to transmit digital data for computers or simply to light up dash gauges in a vehicleLess expensive, thinner, and can carry much more data than copper wiresOptical fiber is nonflammable, lightweight, and flexibleRequires more complex splicing procedures Wiring Diagram FundamentalsN51001 Use wiring diagrams during the diagnosis (troubleshooting) of electrical/electronic circuit problems. (AST/MAST)Wiring diagrams use abstract graphical symbols to represent electrical circuits and their connection or relationship to other components in the systemWiring diagrams are split up into systems and subsystems to reduce complexityManufacturers supply keys for the diagramMany of the symbols are standardized and used universally by manufacturersIn many cases, wires use two colors; the first one is the solid color and the second one is the stripeWiring diagrams are a critical tool when diagnosing electrical circuit faultsAllow you to understand how the circuit was designed Using Wiring DiagramsN51002 Use wiring diagrams to trace electrical/electronic circuits. (MLR)Jorge Menchu’s color coding of the wiring diagram:Print out a copy of the wiring diagram for the circuit being diagnosedColor all of the wires green that are directly connected to “ground”Color all of the wires red that are “hot” at all timesColor all of the wires orange that are “switched to power”Color all of the wires yellow that are “switched to ground”If there are any wires that reverse polarity, such as power window motor wires, mark those with side-by-side orange and yellow linesColor any variable wires, such as signal wires, blueTo use wiring diagrams to diagnose electrical circuits:Identify the correct wiring diagram for the vehicle and system circuit being repaired and print a copyColor each wire on the wiring diagram for the circuit that requires diagnosisNote components, wire coding, and harness connectorsDetermine circuit test points and their location on the wiring diagramFind the same test point on the vehicle and perform the appropriate electrical testDepending on the results of the test, continue to use the wiring diagram to guide you in performing Wire Maintenance and RepairK51003 Repair wiring harness.Terminals can corrode, lose their tension, or push back up inside the connector, leading to poor connections and voltage dropsLook for mechanical damage to the wire or wiring harness itselfPinched wire can also cause either a short circuit or an open circuitEasily spotted by a visual inspectionIf a circuit shorts out and melts one or more wires together within the harness, open up the wiring harness and inspect the wiresStripping Wire InsulationChoose the correct stripping toolSelect the hole that matches the diameter of the wire to be strippedPlace the wire in the hole and close the jaws firmly around it to cut the insulationRemove the insulationTo keep the strands together, give them a light twistInstalling a Solderless TerminalN51003 Inspect, test, repair, and/or replace components, connectors, terminals, harnesses, and wiring in electrical/electronic systems (including solder repairs); determine needed action. (MLR/AST/MAST)Make sure you have the correct size of terminal for the wire to be terminated and that the terminal has the correct volt/amp ratingRemove an appropriate amount of the protective insulation from the wireLightly twist the wire strands and place the terminal onto the wireUse a proper crimping tool for the terminal you are crimpingCrimp the core section firstIf crimping an uninsulated terminal, lightly crimp the insulation tabs so that they hold the insulation firmlyIf crimping a factory terminal, use the proper tool and follow the instructionsSoldering Wires and ConnectorsRosin core solder is used for soldering electrical components and wiresSolder is applied with a hot soldering ironThe soldering iron is heated electrically or by an external source such as a butane or oxyacetylene torchTo solder wires and connectors:Safely position the soldering iron while it is heating upWhile the soldering iron is heating, use wire strippers to remove an appropriate amount of the protective insulation from the wiresTwist the wires together to make a good mechanical connection betweenTin the soldering iron tip and gently heat up the wires while placing the solder opposite of the soldering ironAllow the solder to be drawn into the jointOnce the electrical connection has been made and it has cooled enough for you to handle it, slide the insulator sleeve cover over the joint, and use a heat gun to shrink the tubing around the jointTo solder a wire to a terminal connector, it is best to crimp it in place as before and use the solder to “glue” the joint togetherPlace the heated iron onto the terminal to get it hot enough to melt the solder applied to the end of the crimped wire tabsSome solder will be pulled between the terminal and the wireCover the terminal with heat shrink tubingRepairing a CANbus HarnessN51004 Repair data bus wiring harness. (MAST)Carefully peel back any protective covering and shielding from the area to be repairedIn most cases, splice in a section of one or both wires to maintain equal length after repairCut out the bad section and strip the endsCarefully work a piece of shrink tube up the damaged wireMake sure the wires remain twisted at about one complete twist per inchThe untwisted section should end up less than 2' (50 mm) after repairUsing the correct wire size, twist the strands of the new wire to the old wire on both ends, and solder the wiresSlip the heat shrink tubing in place and shrink it around the jointReplace any protective covering and secure appropriatelyPost-LectureThis section contains various student-centered end-of-chapter activities designed as enhancements to the instructor’s presentation. As time permits, these activities may be presented in class. They are also designed to be used as homework activities.Direct students to read and individually answer the question sets located in the Wrap-Up section at the end of each chapter. Allow approximately 10–20 minutes for this part of the activity.Facilitate a class review and discussion of the answers, allowing students to correct responses as may be needed. Use the answers noted in the Answer Key to assist in building this review.You may wish to ask students to complete this activity on their own and turn in their answers on a separate piece of paper.Review QuestionsThis question set is designed to assist students in understanding the chapter content by asking knowledge-based comprehension questions.Which of the following components can be programmed and are an integral part of other electrical components?SensorsZener diodesMicroprocessorsActuatorsChoose the correct statement.Semiconductor devices use high operating voltages.Semiconductor devices are sensitive to heat and voltage spikes.Semiconductor devices are not reliable.Semiconductor devices need regular maintenance.Which of the following materials is widely used to build high-speed semiconductors?SiliconGermaniumGallium-arsenideSilicon carbideAll of the following statements about transistors are correct except:Transistors are used as a switch and to amplify currents.They are made up of two sections of different polarity.Transistors have two PN junctions.Transistor symbols always have an emitter, base, and a collector.What is the most common use of speed control units in vehicles?To control the fan speed in the HVAC system and the radiatorTo control the speed of the windshieldTo control the speed of the carTo control the speed of the engineWhich of the following types of shielding is used in wiring to prevent electromagnetic interference (EMI)?Special plastic coated wiresSilicon tapeNylon tapeMylar tapeAll of the following statements are true except:Wires are the dominant signal carriers in a vehicle.A number of wiring harnesses are located throughout the vehicle.As technology has developed, usage of wires and cables has reduced.Wires and wiring harnesses are the arteries of the vehicle's electrical system.Fiber optic cable has all of the following advantages over a conventional copper cable except:It can carry much more data than copper wires.It is less affected by interference.Light in one fiber does not interfere with light in another fiber.It is expensive when compared to conventional cables.If both wires in the twisted pair CANbus need to be repaired, it is best to:replace both wires.replace one of the wires.stagger the joints.repair without removing the insulation.Excessive bare wire may:expose the wire to a potential short circuit.reduce the current-carrying capacity of the wire.not achieve a good connection.result in a poor wire-to-terminal connection.ASE Technician A/Technician B Style QuestionsThis question set is designed to assist students in gaining a further understanding of and familiarity with ASE Technician A/Technician B questions.Tech A says that if the specified fuse keeps blowing, it is generally okay to replace it with a larger fuse. Tech B says that a fusible link is one type of circuit protection device. Who is correct?Tech ATech BBoth A and BNeither A nor BTech A says that 18 AWG wire is larger than 12 AWG wire. Tech B says that the larger the diameter of the conductor, the more electrical resistance it has. Who is correct?Tech ATech BBoth A and BNeither A nor BTech A says that some relays are equipped with a suppression diode in parallel with the winding. Tech B says that some relays are equipped with a resistor in parallel with the winding. Who is correct?Tech ATech BBoth A and BNeither A nor BTech A says that NTC thermistors alter their resistance value inversely to temperature (as the temperature increases, resistance value decreases). Tech B says that PTC thermistors are used as throttle position sensors. Who is correct?Tech ATech BBoth A and BNeither A nor BTech A says that a transistor has a single P-N junction. Tech B says that a transistor is a semiconductor device used as a switch and to amplify currents. Who is correct?Tech ATech BBoth A and BNeither A nor BTech A says that wiring diagrams are essentially a map of all of the electrical components and their connections. Tech B says that in many cases, each wire in wire harnesses use two colors; the first one is the solid color, and the second one is the stripe. Who is correct?Tech ATech BBoth A and BNeither A nor BTech A says that a twisted pair is two wires, twisted together, that deliver signals between common components. Tech B says that in many cases, wiring diagrams are set up with power on the top of the diagram and ground on the bottom. Who is correct?Tech ATech BBoth A and BNeither A nor BTech A says that it is best to use a knife or other type of sharp tool to cut away the insulation when stripping a wire. Tech B says that any issues with wiring are more likely to be with the terminals than with the wires themselves. Who is correct?Tech ATech BBoth A and BNeither A nor BTech A says that while soldering wires, apply the solder to the wire opposite the soldering iron. Tech B says that you should heat the wire up until the plastic insulation melts. Who is correct?Tech ATech BBoth A and BNeither A nor BTech A says that a relay is a one-way electrical check valve used in alternators to change AC into DC. Tech B says that a relay uses electromagnetism to open or close a switch. Who is correct?Tech ATech BBoth A and BNeither A nor BSuggested Demos and ExercisesThe following list of suggested demos and exercises is provided to enhance your instruction.Have on display electronic components, like switches, fuses, relays, flashers, etc. Walk the students through the operation of each component. Build several circuits on an electrical trainer using these components and walk the students through the process of how to test these components.Separate the students into two-person teams based on the class size. Have the teams identify electrical components on a lab vehicle using Post-it notes. Show the students how to download a wiring diagram from the online service information and show them how to trace a circuit using a colored highlighter. Separate the students into two-person teams based on the class size. Have the teams download a wiring diagram from the online service information and trace a circuit using a colored highlighter.Have the students complete a task or job sheet for the following NATEF tasks:N51001 Use wiring diagrams during the diagnosis (troubleshooting) of electrical/electronic circuit problems. (AST/MAST)N51002 Use wiring diagrams to trace electrical/electronic circuits. (MLR)Show the class how to use a standard wire gauge.Separate the students into two-person teams based on the class size. Have the teams determine the size of a series of automotive wiring.Show the class how to identify several different types of connectors, including those with connector position assurance clips. Explain that it is especially necessary to guarantee that connectors will stay together in supplemental restraint systems. Demonstrate removal of terminals from several different types of connectors. Demonstrate use of a soldering iron to connect wiring. Point out to the students that they should make sure that the solder joint is smooth; otherwise, a sharp point could puncture shrink wrap and cause a short circuit.Have the students complete a task or job sheet for the following NATEF tasks:N51003 Inspect, test, repair, and/or replace components, connectors, terminals, harnesses, and wiring in electrical/electronic systems (including solder repairs); determine needed action. (MLR/AST/MAST)N51004 Repair data bus wiring harness. (MAST)AssignmentsReview all materials from this chapter and be prepared for a chapter quiz to be administered (date to be determined by instructor).Direct students to read the next chapter in Fundamentals of Automotive Technology: Principles and Practice, 2e as listed on your syllabus to prepare for the next class session. ................
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