start Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 34, the reader should be able to: • • • Prepare for ASE Engine Performance (A8) certification test content area “E” (Computerized Engine Controls Diagnosis and Repair) Explain how to set a digital meter to read volts, amperes, and ohms List the precautions necessary when working with test equipment Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 OBJECTIVES: After studying Chapter 34, the reader should be able to: • • Explain how a digital storage scope differs from an analog scope Describe how to safely connect test equipment or a meter to a circuit or component without doing any harm Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: ì10 display ã AC coupling • AC/DC clamp-on DMM • alternating current (AC) BNC connector cathode ray tube (CRT) • CAT ratings • continuity light • counts • current analog DC coupling • digits • digital meter • digital multimeter (DMM) • digital storage oscilloscope (DSO) • digital volt-ohmmilliammeter (DVOM) • direct current (DC) • duty cycle Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: external trigger • frequency graphing multimeter (GMM) • graticule high-impedance meter inductive ammeter • International Electrotechnical Commission (IEC) kilo • LED test light • logic probe mega • micro • milli oscilloscope • over limit (OL) Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 KEY TERMS: pulse trains • pulse width • pulse width modulation (PWM) resolution • root-mean-square (RMS) scope • self-powered test light test light • time base • trigger level • trigger slope volts per division Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Test equipment must be used by the service tech because electrical signals cannot be seen or felt and therefore must be measured This chapter reviews basics of electrical measurement and provides background for measuring components and circuits in the remaining chapters Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 TEST LIGHTS A test light is simply a light bulb with two wires attached It is used to test for low-voltage level (6 to 12 volts) Battery voltage can’t be seen or felt and can be detected only with test equipment A test light can be purchased or homemade A purchased test light could be labeled as a 6- to 12-volt test light Figure 34–1 A 12-volt test light is attached to a good ground while probing for power Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman Do not purchase a test light designed for household current (110 or 220 volts) It will not light with 12 volts Continued ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Always Test Your Equipment More than one tech has misdiagnosed a problem because the test equipment did not work correctly Examples include the following: Test light bulb burned out A test light bulb can be easily checked by regularly testing the test light bulb across a battery A burned out test light bulb will not be able to detect voltage Meter fuse blown If an ammeter fuse is blown (open), the meter will simply read 0.0 amperes (A) and not conduct current in the circuit If an inline fuse is used in the meter leads, all functions of the meter will not work Volts will read 0.0 all the time and often will read OL (over limit) on all ohmmeter scales Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Figure 34–2 A test light can be used to locate an open in a circuit Note that the test light is grounded at a different location than the circuit itself CAUTION: The use of a continuity test light is not recommended on any electronic circuit Because a continuity light contains a battery and applies voltage, it may harm delicate electronic components Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman 10 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Meter Usage on Hybrid Vehicles - Part CAT I ‑Typically a CAT I meter is used for low-voltage measurements such as voltage measurements at wall outlets in the home Meters with a CAT I rating are usually rated at 300 to 800 volts CAT II ‑A higher-rated meter that would be typically used for checking voltages at the fuse panel in the home Meters with a CAT II rating are usually rated at 300 to 600 volts CAT III ‑The minimum-rated meter that should be used for hybrid vehicles This category is designed for voltage measurements at the service pole transformer CAT III meters are usually rated at 600 to 1,000 volts CAT IV ‑CAT IV meters are for clamp-on meters only If a clamp-on meter also has meter leads for voltage measurements, that part of the meter will be rated as CAT III For best personal protection, use only meters and meter leads that are CAT III or CAT IV rated when measuring voltage on a hybrid vehicle Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman 78 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 Meter Usage on Hybrid Vehicles - Part Always use the highest CAT rating meter, especially when working with hybrid vehicles Figure 34–32 Always use meter leads that are CAT III-rated on a meter that is also CAT III-rated to maintain the protection needed when working on hybrid vehicles Figure 34–31 Be sure to only use a meter that is CAT III-rated when taking electrical voltage measurements on a hybrid vehicle A CAT III 600-volt meter is safer than a CAT II 1,000-volt meter Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman 79 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Digital Meter Usage #1 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman 80 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Digital Meter Usage #1 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) 81 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Digital Meter Usage #1 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) 82 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Digital Meter Usage #1 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) 83 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Digital Meter Usage #2 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman 84 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Digital Meter Usage #2 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) 85 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Digital Meter Usage #2 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) 86 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Digital Meter Usage #2 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) 87 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Digital Meter Usage #2 Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) 88 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 PHOTO SEQUENCE Digital Meter Usage #2 Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) 89 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY Digital multimeter (DMM) and digital volt-ohmmilliammeter (DVOM) are terms commonly used for electronic high-impedance test meters Use of a high-impedance digital meter is required on any computer-related circuit or component Ammeters measure current and must be connected in series in the circuit Voltmeters measure voltage and are connected in parallel Continued Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman 90 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY (cont.) Ohmmeters measure resistance of a component and must be connected in parallel, with the circuit or component disconnected from power Logic probes can indicate the presence of both ground and power Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman 91 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 end Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman 92 ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458