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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 40, the reader should be able to: • • • • Describe how the cranking circuit works Explain how to disassemble and reassemble a starter motor and solenoid Discuss how to test the cranking circuit Describe how to perform cranking system testing procedures 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: ampere-turns • armature bench testing • brush-end housing • brushes commutator-end housing • commutator segments • compound motor (compound-wound) • compression spring • counter- electromotive force (CEMF) • cranking circuit drive coil • drive-end (DE) housing • electromagnetic switch field coils • field poles 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: gear-reduction starters • ground brushes • growler tester holding coil • hold-in winding • hot brushes lap winding main field housing • mesh spring • mica • movable pole shoe neutral safety switch • overrunning clutch permanent-magnet field • plunger lever • pole shoes • positive-engagement starter • pull-in winding 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: remote vehicle start (RVS) series motor • shift fork lever • shunt motor • solenoidoperated starter • starter drive through bolts undercut voltage-drop testing wave winding 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 For any engine to start, it must first be rotated It is the purpose and function of the cranking circuit to create the necessary power by converting electrical energy from the battery into mechanical energy at the starter motor and rotate the engine 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 CRANKING CIRCUIT The cranking circuit includes mechanical and electrical parts required to crank the engine for starting. Early 1900s cranking force was the driver’s arm. Modern cranking circuits include: The Starter motor. The starter is normally a 0.5 to 2.6 horsepower (0.4 to 2.0 kilowatts) electric motor that develops nearly 8 horsepower (6 kilowatts) for a very short time when first cranking a cold engine Figure 40–1 A typical solenoid-operated starter 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 The Battery. The battery must be of the correct capacity and be at least 75% charged to provide the necessary current and voltage for correct operation of the starter The Starter solenoid or relay. The high current required by the starter must be able to be turned on and off. A large switch would be required if the current were controlled by the driver directly. Instead, a small current switch (ignition switch) operates a solenoid or relay that controls the high starter current The Starter drive. The starter drive uses a small gear that contacts the engine flywheel gear and transmits starter motor power to rotate the engine 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 The Ignition switch The ignition switch and safety control switches control the starter motor operation. Figure 40–3 A typical wiring diagram of a starter circuit Figure 40–2 Some columnmounted ignition switches act directly on the contact points, whereas others use a link from lock cylinder to ignition switch The engine is cranked by an electric motor controlled by a keyoperated ignition switch. 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 The ignition switch will not operate the starter unless the transmission is in neutral or park. Many manufacturers a neutral safety switch that opens the circuit between ignition switch and starter to prevent operation unless the gear selector is in neutral or park Neutral safety switches can be adjusted by loosening the holddown screws and moving the switch slightly to be certain the engine will crank only with the transmission in the neutral and park positions Many manufacturers use a mechanical blocking device in the steering column to prevent the driver from turning the key switch to start unless the gear selector is in neutral or park. Many manual transmission vehicles also use a safety switch to permit cranking only if the clutch is depressed 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 Starter DrivetoFlywheel Clearance For proper operation of the starter and absence of abnormal starter noise, there must be a slight clearance between the starter pinion and the engine flywheel ring gear. If clearance is too great, the starter will produce a highpitched whine during cranking. Figure 40–41 A shim (or half shim) may be needed to provide the proper clearance between the flywheel teeth of the engine and the pinion teeth of the starter If the clearance is too small, the starter will produce a high pitched whine after the engine starts, just as the ignition key is released 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 NOTE: Be sure that the locking nuts for the studs are tight. Often the retaining nut that holds the wire to the stud will be properly tightened, but if the stud itself is loose, cranking problems can occur Many GM starters use shims (thin metal strips) between the flywheel and the engine block mounting pad to provide the proper clearance. NOTE: Some manufacturers use shims under starter driveend housings during production. Other manufacturers grind the mounting pads at the factory for proper starter pinion gear clearance. If any GM starter is replaced, the starter pinion must be checked and corrected as necessary to prevent starter damage and excessive noise 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 To be sure the starter is shimmed correctly, use this procedure: Step #1 Place the starter in position; finger tighten mounting bolts Step #2 Use an 1/8 inch diameter drill bit (or gauge tool) and insert between the armature shaft and a tooth of the engine flywheel Step #3 If the gauge tool cannot be inserted, use a fulllength shim across both the holes, moving the starter away from the flywheel Step #4 If the gauge tool is loose between the shaft and the tooth of the engine flywheel, remove a shim or shims Step #5 If no shims have been used and the fit of the gauge tool is too loose, add a half shim to the outside pad only. This moves the starter closer to the teeth of the engine flywheel 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 CAUTION: Be sure to install all factory heat shields to help ensure proper starter operation under all weather and driving conditions NOTE: The major cause of broken driveend housings on starters is too small a clearance. If the clearance cannot be measured, it is better to put a shim between the engine block and the starter than to leave one out and risk breaking a driveend housing 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 Ground Wire Current Flow - Part Before installing a new or rebuilt starter in a vehicle, be sure that both the positive cable and the negative cable are in good condition The reason is all electrical power must have a complete path from the power source, through the electrical loads, and back to the power source This rule is true for all circuits, whether series, parallel, or series-parallel type As the current flows through resistances and loads (such as bulbs and coils), its voltage decreases because of the resistance (electrical load) in the circuit Amperes is the unit of electricity that actually does the work in a circuit The greater the current flow, the more electrical power available Because current flow is actually a measure of the number of electrons making the trip through a circuit, this same number of electrons also must return to the power source The electrical pressure (voltage) on the return (ground) wires is low (almost zero), but the current in amperes must still flow back to the battery The battery ground cable must be just as large as the positive cable because just as many amperes return as leave the battery Still not convinced? 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 Ground Wire Current Flow - Part Connect a starting-charging-testing unit to a vehicle Instead of connecting the ampere probe around the positive cable, connect it around the ground cable (all cables should be within the ampere probe if more than one ground cable is connected to the battery terminal) All ammeter readings should be the same if taken on the positive or negative cables of the battery NOTE: Most startingchargingtesting units use an arrow on the ammeter probe to show polarity. Reversing the direction in which the arrow points is often necessary to read the correct polarity (positive or negative) on the tester display 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 Reuse Drive-End Housings to Be Sure Most General Motors starter motors use a pad mount and attach to the engine with bolts through the drive-end (nose) housing Many times when a starter is replaced on a GM vehicle, the starter makes noise because of improper starter pinion-to-engine flywheel ring gear clearance Instead of spending a lot of time shimming the new starter, simply remove the driveend housing from the original starter and install it on the replacement starter Because the original starter did not produce excessive gear engagement noise, the replacement starter should also be okay Reuse any shims that were used with the original starter This method is better than having to remove and reinstall the replacement starter several times until the proper clearance is determined 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 STARTING SYSTEM TROUBLESHOOTING GUIDE See the chart on Page 432 of your textbook. 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 PHOTO SEQUENCE Starter Overhaul 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 PHOTO SEQUENCE Starter Overhaul (cont.) 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 PHOTO SEQUENCE Starter Overhaul (cont.) 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 PHOTO SEQUENCE Starter Overhaul Automotive Technology: Principles, Diagnosis, and Service, 3rd Edition By James D Halderman (cont.) ©©2008 2009Pearson PearsonEducation, Education,Inc Inc Pearson PearsonPrentice PrenticeHall Hall- -Upper UpperSaddle SaddleRiver, River,NJ NJ07458 07458 SUMMARY All starter motors use the principle of magnetic interaction between the field coils attached to the housing and the magnetic field of the armature Proper operation of the starter motor depends on the battery being at least 75% charged and the battery cables being of the correct size (gauge) and having no more than 0.2volt drop Voltagedrop testing includes cranking the engine, measuring the drop in voltage from the battery to the starter, and measuring the drop in voltage from the negative terminal of the battery to the engine block 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 SUMMARY (cont.) The cranking circuit should be tested for proper amperage draw An open in the control circuit can prevent starter motor operation 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 end 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
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