《汽车专业英语》-Chapter Five Automobile Service Equipment

5.1AutomotiveDiagnosticandTestProcedure5.1.1ASystematicApproachforEffectiveDiagnosisThediagnosticprocedurehasevolvedandisnowaresultofacriticalthoughtprocess，insteadofamechanicalprocess.Inotherwords，ratherthanassumingaspecificcomponentisfaulty，thenreplacingit，thediagnosticthoughtprocessproveswhyyouarereplacingitbasedonfactualtestresults.Usingasymptomtoestablishadiagnosisisimportant；however，actingonthesymptomalonewithoutperformingqualifyingtestscanleadyoudownacostlyandincorrectpath下一页返回5.1AutomotiveDiagnosticandTestProcedureAssumptionsmustbeprovedout“Magicquick-fixes”donotalwayswork.Certainstepsneedtobefollowedwhenaddressinganyproblemwiththevehicle.Thefollowingsystematicapproachforaneffectivediagnosisgivesthetechnicianastrategyandprocesstofollowthatputsthingsinorder.Itcanapplytojustaboutanythingrelatedtothevehiclefromfluidleakstodrivabilityproblems.(1)QuestionsandAnswers(2)ClarifytheComplaint(3)VerifytheComplaint(4)Climate，Speed，Time，Distance，andAction(5)UtilizetheResourcesthatAreAvailabletoYou(6)BeginwithanAreaTest上一页下一页返回5.1AutomotiveDiagnosticandTestProcedure(7)Next，PerformtheSystemTest(8)PinpointorComponentTest(9)ApprovalandRepair(10)ConfirmandRetest上一页下一页返回5.1AutomotiveDiagnosticandTestProcedure5.1.2CustomerServiceandVehicleCare

Customersarethepurposeofyourbusiness.TheyultimatelypaythebillsandyourwagesBecauseofbasichumannature，youwillencounteravarietyofpeopleandbehaviors.Theyarehumanbeings，justlikeyou.Thetypeofcustomerserviceyoudelivercanmakethedifferencebetweenagoodshopandagreatshop.Obviously，customerswanttobetreatedwithcourtesyandrespect.Theyexpectproperandthoroughservicetobeperformedontheirvehicleatafairprice，inareasonabletime.Noonewantstopayforsomethingthatisnotneeded.Whendiscussingaproblemwithcustomers，beunderstandingoftheirneeds.Takingafewextramomentsorafewextrastepswillwincustomersover.上一页下一页返回5.1AutomotiveDiagnosticandTestProcedureYoushouldfollowsomecommon-senseprocedureswhenhandlingacustomer’svehicleThefollowingaresomesimpleyetimportantthingstorememberwhenservicingacustomer’svehicle：①Performaquicksafetycheckbeforetestbydrivingthevehicle（brakes，steering，etc）;②Useseatcovers，steeringwheelcovers，andfloormatswhiletestdriving;③Observeallspeedlimits;④Donotoperatethevehiclebeyonditsdesignedcapacityorability;⑤Uponenteringtheshop，rollthedriver’ssidewindowdowntoavoidaccidentallylockingthekeysinthecar;上一页下一页返回5.1AutomotiveDiagnosticandTestProcedure⑥Usecleanfendercovers;⑦Removeanytoolsthatmaybeinyourpocketsbeforegettingintothevehicle;⑧Performabasic，courtesysafetycheck—lights，tires，inflation，wiperblades，fluidleaks，etc;⑨Donotsmokeinoraroundthevehicle;⑩Donoteatordrinkinthevehicle;上一页下一页返回5.1AutomotiveDiagnosticandTestProcedureKeyWordsandExpressionsDiagnostics—theprocessofidentifyingthecauseornatureofacondition，situation，orproblemtodeterminetheappropriatecorrectiveactiontotakeintherepairofanautomotivesystem故障诊断Tailpipe—thelastpipeoftheexhaustsystemwhichfitsbehindthesilencerandextendstotherearofthevehicle尾管上一页下一页返回5.1AutomotiveDiagnosticandTestProcedureMisfire—thefailureofthefuelchargeinoneormoreenginecylinderstofireorigniteatthepropertime缺火，失火PCM—power-traincontrolmodule动力传动控制模块Drivability—thegeneralqualitativeevaluationofapowertrain’soperatingqualities，includingidlesmoothness，coldandhotstarting，throttleresponse，powerdelivery，andtoleranceforaltitudechanges驾驶性能，操纵性能Aftermarketequipment—accessoriesandreplacementpartsaddedtoavehicleafterithasbeensold售后加装设备上一页下一页返回5.1AutomotiveDiagnosticandTestProcedureTSBs—technicalservicebulletins维修技术公告Grease—alubricant（madefromoilandmetallicsoaps）whichreducesthefrictionbetweenmovingpiecesofmetalandalsopreventsmoisturefromcausingmetaltorust润滑脂上一页返回5.2OnboardDiagnosticsSystems5.2.1WhatItDoes

WheretherealworkoftheOBDIIstandardtakesplaceiswithinthedatasentovertheconnection.Duringnormaloperation，thevehicleisconstantlymonitoringalittlemorethan100standardParameterID（PID）codes.EveryvehiclemustbecapableofsendingorreceivingthesecodesoveritsOBDIIconnection.Thesecodestellthetaleofthesystemsmonitoredbyyourvehicle’semissionssystem，everythingfromfuelsystemstatustoengineandvehiclespeedtothestatusofthevehicle’svariousO2sensors.Ifthereisanerrorwithanyoftheseparametersorifavaluefallsoutsideofapredeterminedsaferange，thevehiclewillilluminateitsCheckEnginelight下一页返回5.2OnboardDiagnosticsSystemsThevehicle’scomputerisabletosendallofthisdiagnosticinformationovertheOBDIIconnectiontoaconnecteddiagnostictoolviaPIDalongwithspecialPIDs，knownastroublecodes，thatdetailtheissue.Thereareabout900possibletroublecodesintheOBDIIstandardreportingoneverythingfromfuelsystemstoemissionscontrolstotransmissionstatus.Thismakesiteasyforamechanicoremissionsofficialtoquicklydiagnoseanissuewithavehicle’sengineandemissionsequipmentwithouthoursofguessingandchecking上一页下一页返回5.2OnboardDiagnosticsSystems5.2.2HandheldScanTools

TheprimarypurposeoftheOBDIIconnectionisforemissionstesting，butoneofthefirstandmostwidespreadapplicationsavailabletoconsumersisthescantoolorcodereaderThesedevicesaresometimesbatterypowered，butnewerunitsmaybepoweredbytheelectricityprovidedbytheOBDconnectionitself.WhenaCheckEnginelightisilluminated，thesehandhelddevicesconnecttotheOBDIIportandsimplyrecordanddisplayanytroublecodethatthevehicleissending.Userscanthenusethecodetoseewhat’swrongwiththecarand，oncetheproblemhasbeenfixed，clearthecodefromthevehicle’smemory，deactivatingtheCheckEnginelightuntilthenextissuearises上一页下一页返回5.2OnboardDiagnosticsSystemsThesedevicesoftenjustdisplaytherawcode，soyou’llneedsomesortofcodereferencetoknowthedifferencebetweenaP0302andaP0455（forthecurious，thefirstmeansthatyourengine’ssecondcylinderismisfiringandthesecondsimplymeansthatyou’veprobablyleftyourgascapoff）.Themost-advancedunitsmayactuallystorethetroublecodesinthedevice’smemorytoberetrievedlaterviatheUSBandcross-referencedagainstInternetdatabasesofcodevaluesandknownissues，suchasOBD-上一页下一页返回5.2OnboardDiagnosticsSystems5.2.3DataLoggersWhereasscantoolsaredesignedtobeconnectedtotheOBDportforquickcodereads，dataloggersaredesignedtobesemi-permanentlyconnectedtothevehicle.Thesesmallerandoften-screenlessdevicesstaywiththevehicleasitisdrivenabout，silentlyloggingalloftheinformationthatthevehicle’sOBDIIportprovides上一页下一页返回5.2OnboardDiagnosticsSystems5.2.4EOBDRegulationsrequireenginemanagementsystemstorecordanyproblemthatislikelytoadverselyeffectemissions，andtostorethefaultandthedistancetraveledsinceitwasdetected.Theinformationmustthenbeavailabletoanycompliantdiagnostictool.Toensurethatvehiclescomplywiththeaboveregulations，astandardhasbeendevelopedcalledtheEuropeanOnBoardDiagnostics（EOBD）.ThisisapartoftheEuropeanstandard，stagethreeemissionslegislation，whichbecomesLawfrom01/01/2001.ForavehicletobesoldinanyEECmembercountryitmustfirstpassavehicletypeapprovaltest上一页下一页返回5.2OnboardDiagnosticsSystems5.2.5TheEOBDProtocol（Language）(1)FreezeFramesThefirsttimeafaultoccurs，thesystemwillnotilluminatetheMIL.Dataaboutthefaultwillbestoredalongwithinformationsuchas：①Fuelmode（openorclosedloop）;②Engineload;③Mixtureformation，trimvalue;④Intakemanifolddepression（whereapplicable）;⑤Engineandvehiclespeed;⑥Distancecoveredsincethefaultwasfirstdiscovered上一页下一页返回5.2OnboardDiagnosticsSystems(2)DriveCyclesTheECMwillstartadrivecycleassoonastheengineisstarted（fromhotorcold）andendswhentheengineisswitchedoffThedrivecycleshouldincludeawarm-upcycle.TheEOBDdrivecyclewillbesimilartotheoneusedintheOBDIIinAmericaAcompletedrivecycleshouldallowthesystemtoperformdiagnosticsonallareasandtorunallmonitors.ForthetechnicianortheEOBDsystemtoperformafulldrivecycle，allofthefollowingconditionswillneedtobemet：①Coldstart②Idle③Thevehiclenowneedstobeaccelerateduptoaspeedofaround50-60mph上一页下一页返回5.2OnboardDiagnosticsSystems④Thevehiclespeedshouldnowbeheldsteadyattheabovespeedforaround3minutes⑤Attheendofthisthree⑥Thevehicleshouldnowbeacceleratedbackuptothesamespeedasbefore—thesamediagnosticsasinstepthreeabovearerun；⑦Thespeedshouldbeheldagain，thistimeforaroundfiveminutesAswellasperformingthesamediagnosticsasinstepthree，thecatalystmonitorisnowrun.Ifthecatalystefficiencyisloworthebatteryhasbeendisconnected,itmaytakeuptofivecompletedrivecyclesfortheECMtodeterminetheeffectivenessofthecatalyst;上一页下一页返回5.2OnboardDiagnosticsSystems⑧Finallythevehicleshouldbedecelerated，asinstepfive，whenthesametestswillberun;⑨Obviouslythiscycleisverycomplex,itmaytakeseveraltripstocomplete(3)Warm-UpCycles(4)TripsAtrip，likeadrivecycle，iscommencedwhenthevehicleisstarted，hotorcold，andendswhenallthemonitorshavebeencompletedThisprocesscantakeplaceoveranumberofdrivecycles.上一页下一页返回5.2OnboardDiagnosticsSystems(5)Short-TermFuelTrimsThisisthevariationinoxygencontentasmeasuredbytheoxygensensor.Itisusedtocontroltheamountoffuelinjected.(6)Long-TermFuelTrimsAsforshort-termfueltrimbutrecordedoverapredeterminednumberofsecondsinordertoapplyapermanentcorrectionfact(7)CombustionMisfireMonitoringSomevehiclemanufacturersusethecrankshaftsensorsignalinthemonitoringofmisfires上一页下一页返回5.2OnboardDiagnosticsSystems(8)Post-CatalystOxygenSensorsTheEOBDrequiresasecondoxygensensortobemounteddownstreamofthecatalyticconverter.ThejobofthissensorisalsotomonitorthemixturestrengthinorderthattheECMcanjudgetheeffectivenessofthecatalystThefrequencyofthesignaliscomparedwiththatofthepre-catalystsensorandifthesignalsaresimilar，thecatalystisinefficient.Ofcourse，thiscomparisoncanonlybeachievedundercertainconditions，theenginewillneedtobewarmandthevehiclemustberunninginclosedloopmode上一页下一页返回5.2OnboardDiagnosticsSystems(9)OtherAreasofMeasurement①Ignition：lowtensionignitionsystems，crankshaftsensor，knocksensor;②FuelSystem：fueltanklevels，fuelpumprelay，injectioncircuit，massairflowsensor，throttlepositionsensor，manifoldabsolutepressuresensor，coolanttemperaturesensor，intakemanifoldtemperaturesensor，camshaftsensor;③IdleSystem：idleaircontrolvalves，intakemanifoldrunnercontrolvalves;④AncillaryMeasurements：theECMmemory，airconditioning，transmissionoiltemperatureandcoolingfancircuits上一页下一页返回5.2OnboardDiagnosticsSystems5.2.6VehicleandTestEquipmentConnectors（J1962）

ForthevehicleconnectortocomplywiththeEOBDregulations，theconnectormustbemountedinthedrivercompartmentofthevehicle，preferablybetweenthesteeringcolumnandthecentrelineofthevehicle，andshouldbeeasilyaccessiblefromthedriver’sseat.Accesstotheconnectormustbepossiblewithouttheneedforanytoolstoremovecoversorbarriers.Theconnectorshouldbelocatedsoastopermitaonehandedorblindinsertionoutofviewofthevehicleoccupants，butvisibletoacrouchedtechnician上一页下一页返回5.2OnboardDiagnosticsSystemsBoththevehicleandtestequipmentconnectorsshouldbecapableofcontaining16pins，thevehicleconnectors,pinsshouldbefemaleandthetestequipmentmale，andbothshouldbe“D”shaped（J1962）.上一页下一页返回5.2OnboardDiagnosticsSystems5.2.7RequiredFunctionsoftheTestEquipmenThetestequipmentmustbecapableofprovidingallofthefollowingbasicfunctions：①Automaticdeterminationofthecommunicationprotocolbeingused②Obtaininganddisplayingresultsofonboarddiagnosticevaluation③Obtaininganddisplayingdiagnostictroublecodes（DTCs）.④Obtaininganddisplayinglivereadingsatthetimeofthetest⑤Obtaininganddisplayingfreezeframedatarelatingtoastoredtroubleco上一页下一页返回5.2OnboardDiagnosticsSystems⑥Clearingallstoredtroublecodes，freezeframedataanddiagnosticevaluations⑦Obtaininganddisplayingtestrelatedparametersandresults⑧Provideausermanualandhelpfacility

上一页下一页返回5.2OnboardDiagnosticsSystems5.2.8BasicOperationofTestEquipment

Oncethetestequipmenthasbeenconnectedtothevehicleandpoweredup,itautomaticallyinterrogatestheECMtoestablishwhichofthecommunicationprotocolsthevehiclesuses.ThisprocessdoesnotrequireanyuserinputWhentheprotocolhasbeenestablished,theuserwillbegiventhechoiceofwhatdatatheywishtodisplay(1)DisplayingDiagnosticTroubleCodes(2)DisplayingLiveDataReadings(3)DisplayingFreezeFrameData(4)ClearingDTCs上一页下一页返回5.2OnboardDiagnosticsSystems5.2.9TheOBDⅢTheOBDIIItakestheOBDIItothenextlevel.TheOBDIIIusesminiatureradiotranspondertechnology（similartoautomaticelectronictollcollectionsystems）.TheOBDIIIequippedvehiclewillbeabletoreportemissionsproblemsdirectlytoaregulatoryagencyThetranspondercommunicatesthevehicleVINnumberandanydiagnosticcodesthatarepresentThesystemcanbesetuptoautomaticallyreportanemissionsproblemviaacellularorsatellitelinktheinstanttheSESlightcomeson，ortoansweraqueryfromacellular，satelliteorroadsidesignalastoitscurrentemissionsperformancestatus.上一页下一页返回5.2OnboardDiagnosticsSystemsAsystembuiltbyGMHughesElectronicshasalreadybeenevaluatedbyARB,whichusesaroadsidetransmittertointerrogatevehiclesastheypassbyThesystemusesultralowpower10milliwattreceiverstationsand1milliwatttransmitters（whichisabout1，000timeslesspowerthanatypicalcellulartelephone&aboutthesizeofasmallcalculator）withabroadcastfrequencyof915MHzThesystemiscapableofretrievinginformationfrom8lanesofbumper-to-bumpertrafficoratspeedsupto100mph!Whenthevehiclereceiverhearsthequerysignalfromastationaryorportableroadsidetransmitter，ittransmitsbackananswerintheformofthevehicle’s17-digitVINnumberplusan“okay”signaloranytroublecodesthatmaybepresent.Theinformationcanthenbeusedtoidentifyvehiclesthatareinviolationofcleanairstatutessoanoticecanbesentthatrepairsorsmogtestingisrequired.上一页下一页返回5.2OnboardDiagnosticsSystemsThebasicapproachcouldalsobeusedwithexistingcellularphonelinks（localstationnetworks）orsatellitesystems.Tokeepmotoristsfromtampingwithordisablingtheirtelemetrysystems，vehiclescouldbeinterrogatedrandomlyoronascheduledbasistomonitortheirconditions.TheOBDIIItelemetrycouldalsobecombinedwithGlobalPositioningSystem（GPS）technologytodocumentormonitorthewhereaboutsofvehicles.上一页下一页返回5.2OnboardDiagnosticsSystemsKeyWordsandExpressionsOn-boarddiagnosis—diagnosisperformedbymeanswithinavehicle车载故障诊断CAN—ControllerAreaNetwork（standardizedprotocoldevelopedbyBoschfornetworkedsystems）.局域网控制器EOBD—EuropeanOnBoardDiagnostics（Europeanemission-relatedlegislation）.欧洲车载诊断系统Misfire—thefailureofthefuelchargeinoneormoreenginecylinderstofireorigniteatthepropertimeAlsocalledmissingorbackfiring失火MIL—MalfunctionIndicatorLamp（indicatesemission-relatedfaultstothedriver）.故障指示灯上一页下一页返回5.2OnboardDiagnosticsSystemsFemale—afittinginsideanotherpartUsuallywheretwopartsformaconnectionofsomekind，thefemalepartisthesocketorholeintowhichanotherpieceisinserted插座Steeringwheel—thedevicethattheoperatorusestocontrolthedirectionofthefrontwheels.Mostarecircularwithspokesthatattachtothesteeringcolumn方向盘PIDcode—aacronymforParameterIdentificationLocation参数识别码CheckEnginelight—alightontheinstrumentpanelthatletsthedriverknowofanydetectableenginemanagementsystemmalfunctions.Alsousedasanemissionmaintenancereminderlightonsomevehicles.Oftenwhenthislightison，atroublecodeisstoredinthecomputer检查发动机灯上一页下一页返回5.2OnboardDiagnosticsSystemsDiagnostictroublecode—anumericidentifierforafaultconditionidentifiedbytheon-boarddiagnosticsystem故障诊断代码Supplementalrestraintsystem（SRS）—themanufacturer’snameforasystemwhichusesairbagstorestrainoccupantsintheeventofacollisionTheymaybeplacedonthedashordoorsorevenintheshoulderstrap辅助约束系统Codereader—adeviceusedinconjunctionwiththevehicle’sdiagnosticsystem，providingaread-outofstatusofthevariouscomponents代码阅读器上一页下一页返回5.2OnboardDiagnosticsSystemsECM（enginecontrolmodule）—anadvancedelectroniccomputerwhichmonitorsengineconditionsandthencontrolsenginesettingstooptimizethecombustionoftheair/fuelmixture发动机控制模块DriveCycle—anyjourneyofavehicleinwhichtheenginetemperatureisraisedfromcold（below49℃）tonormaloperatingtemperature（above71℃）.驾驶循环［车辆在发动机温度从冷态（低于49℃）升到正常工作温度（高于71℃）之间的行程］Demister—anelectricorhotairdevicetoremovethefogoricefromboththeinsideandoutsideofthewindshield，backlight（i.e，rearwindow）orevenmirrorsSomearedesignedtoremovefogfromthesidewindows.ABritishtermisusedforadefoggerordefroster除雾器，除冰器上一页下一页返回5.2OnboardDiagnosticsSystemsFuelTrim—anOBDtermreferringtofeedbackadjustmentstothebasefuelschedule燃油修正VIN—VehicleIdentificationNumber（VIN）,anumberassignedtoavehiclebythemanufacturerprimarilyforregistrationandidentificationpurposes（consistingofnumeralsandletters）.车辆识别码上一页返回5.3EngineAnalyzers5.3.1DiagnosingwithanEngineAnalyzerIftheshoppossessesacomputerizedengineanalyzer，theabilitytocapturelargeamountsofengineandcomputerdatainashortperiodhasincreasedsignificantlyTheappealingaspectofusingthispieceofequipmentisthatitisversatileandmulti-functionalwiththecapabilitytocarryoutalmostanynecessaryengineperformance-relatedtestItcanbeusedasadiagnosticanalyzertoperformalltestsrelatedtomechanical，electrical，ignition，fueldelivery，andcomputersystems

下一页返回5.3EngineAnalyzersTheobjectiveistogatherasmuchengineperformance-relatedinformationaspossibleintheshortestamountoftime.Aftertakingafewminutestoconnecttothevehicleforeitheracompletetestsequenceorindividualtests，theanalyzerisreadyfordatacollection.Performingacompletetestwillquicklygatherenginedatathatotherwisecouldtakeagreatdealoftime上一页下一页返回5.3EngineAnalyzers5.3.2CompleteTestsThecompletetestbeginswithenteringinformationintotheanalyzeraboutthevehiclesuchasyear，make，model，andengine.Next，thecomputerloadsengineperformancelimitslatercomparedwithactualtestresultsforuseindiagnostics.Thetechnicianisguidedthroughthetestswithscreenpromptssuchasvehicleconnectionsandvisualinspections（seeFig5-1）.上一页下一页返回5.3EngineAnalyzersThefollowingenginetestsareportionsofthecompletetest：(1)CrankingTest(2)RunningTests(3)SecondaryIgnitionorkVTests(4)CylinderPowerBalanceTests上一页下一页返回5.3EngineAnalyzers5.3.3OperatorSelectableTestsOtherpinpointtestscanbeselectedeitherinconjunctionwiththeCompleteTestorseparately.Thesetestscanbeperformedasaportionofthetestslistedaboveorbyselectinganyofthefollowing：①DMMtests，includingallvolt，ohm，andlowamps;②Frequencyfunctionsandcalculations;③Dualtracelabscopefunctionsfortestinganarrayofinputsignalsandoutputcommands，includingpressureandvacuumwaveforms（seeFig5-6）;④Singleordualignitionoscilloscopeonanyignitionsystemwithorwithoutexhaustanalyzerreadings（seeFig5-7）;上一页下一页返回5.3EngineAnalyzers⑤Separatebattery，starting，andchargingsystemtestswithhighampsinductiveprobesandalternatorwaveforms（seeFig5-8)⑥Analyzerpoweredvacuumpumpwithvariablevacuumadjustmentandgauge;⑦Manualcylinderpowerbalancetest;⑧Emissionstestingandair/fuelratiodisplay;⑨Diagnosticreporting上一页下一页返回5.3EngineAnalyzers5.3.4On-BoardComputerDiagnosesThevehicle’scomputersystemiseitherincorporatedintothetestroutineorcanbeviewedindependentlyfromanyoftheenginetests.Testcapabilitiesaretypicallyafunctionofthevehicle’scomputer.Thisdeterminesthetypeofteststhatcanbeperformedviathecomputerandotherfunctionssuchasthetypeofdatadisplayedandrefreshrates.Theteststypicallyinclude：上一页下一页返回5.3EngineAnalyzers①Standardandbi-directionaldatacommunicationswithvehiclecomputersystems;②Diagnostictroublecode（DTC）retrievalanddefinitions;③Diagnosticchartsforcodesandtroubleshooting;④Vehicledatastreams;⑤Specialtytests;⑥OBDIIenhancedtests;⑦Datacaptureandstorageforplaybackandgraphicalanalysis.上一页下一页返回5.3EngineAnalyzersKeyWordsandExpressionsEngineanalyzer—anelectronicenginetestingdevicewhich（becauseofitssize）usedtobeplacedinacabinetoramovablestand.Themodernunitsareoftenhand-heldandareconnectedtothevehicle’sdiagnosticsocket（asinthecaseofthediagnosticread-outbox），whichprovidesdataonallaspectsoftheengine’sstateoftune发动机分析仪Pressuregauge—atoolusedtomeasureagas，aliquid，orairinpoundspersquareinch（psi）.压强计Compressiongauge—agaugeusedtotestthecompressioninthecylinders压缩比测试计上一页下一页返回5.3EngineAnalyzersVacuumgauge—agaugeusedtodeterminetheamountofvacuumexistinginachamber真空泄漏检测计Tachometer（tach）—adeviceusedtoindicatethespeedoftheengineinrpmThetachometerismountedonornearthedashboard（someevenappearonthehoodandothersinaheads-updisplayonthewindshield）.Ithelpsthedrivertoknowtheoptimumrpmforchanginggearsonmanualtransmissions.Atachometerisalsoadiagnosticdevicewhichamechanicusestodetermineidlespeedandothercarburetorandrunningsettings.Alsocalleda“revcounter”发动机转速表上一页下一页返回5.3EngineAnalyzersTiminglight—astroboscopicunitthatisconnectedtothesecondarycircuittoproduceflashesoflightinunisonwiththefiringofaspecificsparkplug正时灯（用来设定点火正时的频闪灯）Oscilloscope—anelectronicmeasurementdeviceusedtodisplaywaveformsortracesofsignals示波器Scantool—adevicethatinterfaceswithandcommunicatesinformationonadatalink诊断仪Lead—ashortconnectingwirewhichmakeselectricalcontactbetweentwopoints导线上一页下一页返回5.3EngineAnalyzersTroublecode—theengineselfdiagnosisTheelectroniccontrolmodulequestionssensorreadingandstorescodesforwhichcircuittroubleislocated故障码Specifications—alistofthemeasurementsofeachcomponentofavehicleandtherequirementsforproperinstallation技术参数表CRT—theacronymforcathoderaytube阴极射线管Digitalmultimeter（DMM）—thesameasamultimeter，butusesadigitalReadoutandcanusuallybeusedtotestacomputerizedvehicle数字式万用表上一页下一页返回5.3EngineAnalyzersMake—thebrandnameofacarortruck（i.e，Chevrolet，Ford，Dodge，Honda）.车辆品牌名称Model—avehiclecanbedesignatedbyanumberofparameters：manufacturer，make，model，series，enginesize，etcForexample：GM，Cadillac，DeVille，Concours，Northstar45engine车型Dualtracelabscope—adevicethatcandisplaytwoactive，independentpatternsatthesametime双踪示波器Diagnostictroublecode（DTC）—Codesdisplayedoninstrumentpanelswhichcanbeusedtodeterminetheareainthesystemwheremalfunctionmaybelocated故障诊断码上一页返回5.4DedicatedTestEquipmentRepairingthemodernautomobilerequirestheuseofvarioustoolsManyofthesetoolsarecommonhandandpowertoolsusedeverydaybyatechnicianOthertoolsareveryspecializedandareonlyforspecificrepairsonspecificsystemsorvehicles(1)ALiftAliftisusedtoraiseavehiclesoatechniciancanworkunderthevehicle.Theliftarmsmustbeplacedunderthecaratthemanufacturer’srecommendedliftpoints.Thereareseveraltypesofvehicleliftsinusetoday.Categoriesofliftsincludesingle，double，andfour-postvarieties下一页返回5.4DedicatedTestEquipment(2)ExhaustAnalyzersExhaustanalyzersareveryvaluablediagnostictoolsBylookingatthequalityofanengine’sexhaust，atechnicianisabletolookattheeffectsofthecombustionprocess.Anydefectcanchangeinexhaustquality.Theamountandtypeofchangecanserveasthebasisofdiagnostics(3)Cyl