Ch09

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Ch09

  1. 2. OBJECTIVES <ul><li>After studying Chapter 9, the reader should be able to: </li></ul><ul><ul><ul><li>Prepare for ASE Engine Performance (A8) certification test content area “F” (Engine Electrical Systems Diagnosis and Repair). </li></ul></ul></ul><ul><ul><ul><li>Discuss methods that can be used to check the condition of a battery. </li></ul></ul></ul><ul><ul><ul><li>Describe how to perform a battery drain test and how to isolate the cause. </li></ul></ul></ul><ul><ul><ul><li>Explain how to test the condition of the starter. </li></ul></ul></ul>(Continued)
  2. 3. <ul><ul><ul><li>List the steps necessary to perform a voltage-drop test. </li></ul></ul></ul><ul><ul><ul><li>Explain how to test the generator (alternator). </li></ul></ul></ul>
  3. 4. PURPOSE AND FUNCTION OF A BATTERY <ul><li>The primary purpose of an automotive battery is to provide a source of electrical power for starting and for electrical demands that exceed generator output. The battery also acts as a stabilizer to the voltage for the entire electrical system. </li></ul>
  4. 5. BATTERY RATINGS <ul><li>Cold-Cranking Amperes </li></ul><ul><ul><li>The cold-cranking power of a battery is the number of amperes that can be supplied by a battery at 0 。 F (-18 。 C ) for 30 seconds while the battery still maintains a voltage of 1.2 volts per cell or higher. </li></ul></ul><ul><ul><li>The cold-cranking performance rating is called cold-cranking amperes (CCA). </li></ul></ul>(Continued)
  5. 6. <ul><li>Cranking Amperes </li></ul><ul><ul><li>Cranking amperes (CA) are not the same as CCA, but are often advertised and labeled on batteries. The designation CA refers to the number of amperes that can be supplied by the battery at 32 。 F (0 。 C ). This rating results in a higher number than the more stringent rating of CCA. </li></ul></ul>(Continued)
  6. 7. <ul><li>Marine Cranking Amperes </li></ul><ul><ul><li>Marine cranking ampere (MCA) is similar to cranking amperes (CA) and is tested at 32 。 F (0 。 C ). </li></ul></ul>(Continued)
  7. 8. <ul><li>Reserve Capacity </li></ul><ul><ul><li>The reserve capacity rating for batteries is the number of minutes for which the battery can produce 25 A and still have a battery voltage of 1.75 volts per cell (10.5 volts for a 12-volt battery). This rating is actually a measurement of the time for which a vehicle can be driven in the event of a charging system failure. </li></ul></ul>(Continued)
  8. 9. Figure 9-1 This battery has a CCA of 550 A, cranking amperes (CA) of 680 A, and load test amperes of 270 A as listed on the top label. Not all batteries have this much information.
  9. 10. SYMPTOMS OF A WEAK OR DEFECTIVE BATTERY <ul><li>Symptoms of a weak or defective battery are as follows: </li></ul><ul><ul><li>Engine cranking speed is slower than normal. </li></ul></ul><ul><ul><li>Headlights are dimmer than normal when the engine is idling. Normal headlight brightness returns when the engine is above idle, which indicates that the charging circuit (generator) is functioning correctly. </li></ul></ul>(Continued)
  10. 11. <ul><ul><li>Slower-than-normal turn signal operation at idle only. (Normal turn signal operation is observed above idle.) </li></ul></ul><ul><ul><li>Battery uses water in one or more cells. </li></ul></ul>
  11. 12. BATTERY SERVICE SAFETY CONSIDERATIONS <ul><li>To help prevent physical injury or damage to the vehicle, adhere to the following safety procedures: </li></ul>(Continued)
  12. 13. <ul><ul><li>When working on any electrical component on a vehicle, disconnect the negative battery cable from the battery. When the negative cable is disconnected, all electrical circuits in the vehicle will be open, which will prevent accidental electrical contact between an electrical component and ground. Any electrical spark has the potential to cause explosion and personal injury. </li></ul></ul>(Continued)
  13. 14. <ul><ul><li>Wear eye protection when working around any battery. </li></ul></ul><ul><ul><li>Wear protective clothing to avoid skin contact with battery acid. </li></ul></ul><ul><ul><li>Adhere to all safety precautions as stated in the service procedures for the equipment used for battery service and testing. </li></ul></ul><ul><ul><li>Never smoke or use an open flame around any battery. </li></ul></ul>
  14. 15. BATTERY VISUAL INSPECTION <ul><li>Check the battery cables for corrosion and tightness. </li></ul><ul><li>If possible, remove the covers and observe the level of the electrolyte. </li></ul>(Continued)
  15. 16. Figure 9-2 Corrosion on a battery cable could be an indication that the battery is either being overcharged or is sulfated, creating a lot of gassing of the electrolyte.
  16. 17. Figure 9-3 A visual inspection on this battery showed that the electrolyte level was below the plates in all cells.
  17. 18. BATTERY VOLTAGE TEST <ul><li>Testing the battery voltage with a voltmeter is a simple method for determining the state of charge of any battery. </li></ul><ul><li>Open-circuit battery voltage test </li></ul><ul><ul><li>Connect a voltmeter to the positive (+) and negative (-) terminals of the battery. Set the voltmeter to read DC volts. </li></ul></ul>(Continued)
  18. 19. <ul><ul><li>If the battery has just been charged or the vehicle has recently been driven, it is necessary to remove the surface charge from the battery before testing. A surface charge is a higher-than-normal voltage found only on the surface of the battery plates. The surface charge is quickly removed when the battery is loaded and therefore does not accurately represent the true state of charge of the battery. </li></ul></ul>(Continued)
  19. 20. <ul><ul><li>To remove the surface charge, turn the headlights on high beam (brights) for 1 minute, then turn the headlights off and wait 2 minutes. </li></ul></ul><ul><ul><li>Read the voltmeter and compare the results with the following state-of-charge chart. The voltages shown are for a battery at or near room temperature (70 。 to 80 。 F , 21 。 to 27 。 C ). </li></ul></ul>(Continued)
  20. 21. (Continued) Discharged 11.9 or lower 25% charged 12.0 50% charged 12.2 75% charged 12.4 100% charged 12.6 or higher State of Charge Battery Voltage (V)
  21. 22. <ul><li>Most scan tools can display battery or system voltage and engine speed in RPM. Connect a scan tool to the data link connector (DLC) and perform the following while watching the scan tool display </li></ul><ul><ul><li>RPM during cranking - should be 80 to 250 RPMs </li></ul></ul><ul><ul><li>Battery voltage during cranking - should be above 9.6 volts </li></ul></ul>(Continued)
  22. 23. Figure 9-4 (a) A Battery with only 9 volts is definitely discharged and must be recharged before it can be tested. A
  23. 24. Figure 9-4 (continued) (b) This dirty battery is slightly discharged. B
  24. 25. Figure 9-5 (a) Voltimeter showing the battery voltage after the headlights were on (engine off) for 1 minute. A
  25. 26. Figure 9-5 (continued) (b) Headlights were turned off and the battery voltage quickly recovered to indicate 12.6 volts. B
  26. 27. Figure 9-6 A DaimlerChrysler DRB III being used to check battery voltage on a DaimlerChrysler vehicle.
  27. 28. BATTERY LOAD TESTING <ul><li>The proper electrical load to be used to test a battery is one-half of the CCA rating or three times the ampere-hour rating, with a minimum of a 150-A load. Apply the load for a full 15 seconds and then observe the voltmeter while the battery is still under load. A good battery should indicate above 9.6 volts. </li></ul>(Continued)
  28. 29. <ul><li>The load test is sometimes called the 1-minute test, because many battery manufacturers recommend performing the load test twice. First, use the load period (15 seconds) to remove the surface charge on the battery; then wait for 30 seconds to allow time for the battery to recover. </li></ul>(Continued)
  29. 30. <ul><li>Load the battery again for 15 seconds. Total time required is 60 seconds (15 + 30 + 15 = 60 seconds or 1 minute). This method provides a true indication of the condition of the battery. </li></ul>(Continued)
  30. 31. Figure 9-7 A Bear Automotive starting and charging tester. This tester automatically loads the battery for 15 seconds to remove the surface charge, waits 30 seconds to allow the battery to recover, and then again loads the battery. The LCD indicates the status of the battery.
  31. 32. Figure 9-8 A Sun Electric VAT-40 (voltage amp tester, model 40) connected to a battery for load testing. The technician turns the load knob until the ammeter registers an amperage reading equal to one-half the battery’s CCA rating. The load is maintained for 15 seconds, and the voltage of the battery should be higher than 9.6 volts at the end of the time period with the load still applied.
  32. 33. Figure 9-9 Typical battery load tester hookup.
  33. 34. CONDUCTANCE TESTING <ul><li>General Motors, Ford and DaimlerChrysler specify that a conductance tester be used to test batteries in vehicles still under factory warranty. The tester uses its internal electronic circuitry to determine the state of charge and capacity of the battery by measuring the voltage and conductance of the plates. </li></ul>(Continued)
  34. 35. <ul><li>Connect the unit to the positive and negative terminals of the battery, and after entering the CCA rating (if known), push the arrow keys so the tester determines one of the following: </li></ul><ul><ul><li>Good battery. The battery can return to service. </li></ul></ul><ul><ul><li>Charge and retest. Fully recharge the battery and return it to service. </li></ul></ul>(Continued)
  35. 36. <ul><ul><li>Replace the battery. The battery is not serviceable and should be replaced. </li></ul></ul><ul><ul><li>Bad cell – replace. The battery is not serviceable and should be replaced. </li></ul></ul><ul><li>CAUTION: Test results can be incorrectly reported on the display if proper, clean connections to the battery are not made. Also be sure that all accessories and the ignition switch is in the off position. </li></ul>(Continued)
  36. 37. Figure 9-10 A capacitance-type battery tester. (a) The up and down arrow keys are used to answer questions about the battery before it is tested. A
  37. 38. Figure 9-10 (continued) A capacitance-type battery tester. (b) This battery shows a calculated CCA of 729 A and a voltage of 12.37 volts. The display indicates that the battery is good, but should be charged before returning the vehicle to service. B
  38. 39. Figure 9-10 (continued) A capacitance-type battery tester. (c) A test code is displayed for warranty record-keeping purposes. C
  39. 40. JUMP STARTING <ul><li>To safely jump start a vehicle without causing harm, use the following procedure: </li></ul><ul><ul><li>Be certain the ignition switch is off on both vehicles. </li></ul></ul><ul><ul><li>Connect good-quality copper jumper cables </li></ul></ul>(Continued)
  40. 41. <ul><ul><li>Start the vehicle with the good battery and allow it to run for 5 to 10 minutes. This allows the generator of the good vehicle to charge the battery on the disabled vehicle. </li></ul></ul><ul><ul><li>Start the disabled vehicle, and after the engine is operating smoothly, disconnect the jumper cables in the reverse order of step 2. </li></ul></ul>(Continued)
  41. 42. Figure 9-11 Jumper cable usage guide.
  42. 43. BATTERY CHARGING <ul><li>If the state of charge (SOC) of a battery is low, it must be recharged. It is best to slow-charge any battery to prevent possible overheating damage to the battery. </li></ul>(Continued)
  43. 44. <ul><li>The initial charge rate should be about 35 A for 30 minutes to help start the charging process. Fast-charging a battery increases the temperature of the battery and can cause warping of the plates inside the battery. </li></ul>(Continued)
  44. 45. <ul><li>The battery temperature should not exceed 125 。 F (hot to the touch). Most batteries should be charged at a rate equal to 1% of the battery's CCA rating. </li></ul><ul><ul><li>Fast charge: 15 A maximum </li></ul></ul><ul><ul><li>Slow charge: 5 A maximum </li></ul></ul>(Continued)
  45. 46. Figure 9-12 This battery charger is charging the battery at a 10-A rate. This slow rate is easier on the battery than a fast charge, which may overheat the battery and cause warpage of the plates inside the battery.
  46. 47. BATTERY SERVICE <ul><li>Before returning the vehicle to the customer, check and service the following items as necessary. </li></ul><ul><ul><li>Neutralize and clean any corrosion from the battery terminals </li></ul></ul><ul><ul><li>Carefully inspect the battery cables by visual inspection and clean terminals as needed </li></ul></ul><ul><ul><li>Check the tightness and cleanliness of all ground connections </li></ul></ul>(Continued)
  47. 48. <ul><li>A memory saver may be needed to keep the radio powered when the battery is being disconnected. </li></ul>(Continued)
  48. 49. Figure 9-13 Cleaning a corroded battery terminal using a baking soda and water paste. For best results, the cable should be removed from the battery terminal before cleaning.
  49. 50. Figure 9-14 This battery cable was found corroded underneath. The corrosion had eaten through the insulation yet was not noticeable without careful inspection. This cable should be replaced.
  50. 51. Figure 9-15 All battery connections should be thoroughly inspected, especially the ground where they attach to the body of the vehicle. Be especially aware of any body work or previous repair that may have resulted in a poor connection between the body and the negative terminal of the battery.
  51. 52. Figure 9-16 (a) Memory saver. The part numbers represent components from Radio Shack“. (b) A schematic drawing of the same memory saver.
  52. 53. Figure 9-17 This technician cleverly made a tool using an old lantern battery connected to a lighter plug to be used as a memory saver. The technician kept the lantern and simply connected the lighter plug pigtail to the lantern battery terminals. A lantern battery is better to use than a small 9-volt battery in case someone opens the door of the vehicle while the memory saver is plugged in. A small 9-volt battery would be quickly drained, whereas the lantern battery has enough capacity to light the interior lights and still have enough charge to keep the memories alive.
  53. 54. BATTERY ELECTRICAL DRAIN TEST <ul><li>The battery electrical drain test determines if some component or circuit in a vehicle or truck is causing a drain on the battery when everything is off. This test is also called the ignition off-draw (IOD) or parasitic load test. </li></ul>(Continued)
  54. 55. <ul><li>This test should be performed when one of the following conditions exists: </li></ul><ul><ul><li>When a battery is being charged or replaced (a battery drain could have been the cause for charging or replacing the battery) </li></ul></ul><ul><ul><li>When the battery is suspected of being drained </li></ul></ul>(Continued)
  55. 56. <ul><li>Normal battery drain is usually about 20 to 30 mA (0.02 to 0.03 A). Most vehicle manufacturers recommend repairing the cause of any drain that exceeds 50 mA (0.05A). </li></ul>(Continued)
  56. 57. <ul><li>Some manufacturers relate maximum allowable parasitic load to the size of the battery. The higher the battery capacity, the greater the allowable load. The maximum allowable drain on a battery can be calculated by dividing the reserve capacity of the battery in minutes by 4 to get the maximum allowable drain in milliamps. </li></ul>(Continued)
  57. 58. <ul><li>For example; If a battery had a reserve capacity of 100 minutes, it would have a maximum allowable parasitic load of 25 mA (100 / 4 = 25 mA). </li></ul>
  58. 59. BATTERY ELECTRICAL DRAIN TESTING USING AN AMMETER <ul><li>The ammeter method is the most accurate way to test for a possible battery drain. Connect an ammeter in series between the terminal of the battery and the disconnected cable. </li></ul>(Continued)
  59. 60. <ul><li>Many DMMs have an ammeter scale that can be used to safely and accurately test for an abnormal parasitic electrical drain. </li></ul><ul><li>The fastest and easiest method to measure battery electrical drain is to connect an inductive DC ammeter that is capable of measuring low current (10 mA). </li></ul>(Continued)
  60. 61. <ul><li>Following is the procedure for performing the battery electrical drain test using an ammeter: </li></ul><ul><ul><li>Make certain that all lights, accessories, and ignition are off. </li></ul></ul><ul><ul><li>Check all vehicle doors to be certain that the interior courtesy (dome) lights are off. </li></ul></ul><ul><ul><li>Disconnect the negative battery cable and install a parasitic load tool as shown in Figure 9-20. </li></ul></ul>(Continued)
  61. 62. <ul><ul><li>Start the engine and drive the vehicle about 10 minutes, being sure to turn on all the lights and accessories including the radio. </li></ul></ul><ul><ul><li>Turn the engine and all accessories off including the underhood light. </li></ul></ul><ul><ul><li>Connect an ammeter across the parasitic load tool switch and wait 10 minutes for all computers and circuits to shut down. </li></ul></ul><ul><ul><li>Open the switch on the load tool and read the battery electrical drain on the meter display. </li></ul></ul>(Continued)
  62. 63. <ul><li>Results: Normal = 10 to 30 mA (0.02 to 0.03 A) </li></ul><ul><ul><li>Maximum allowable = 50 mA (0.05 A) </li></ul></ul><ul><li>Be sure to reset the clock and antitheft radio if equipped. </li></ul>(Continued)
  63. 64. <ul><li>If there is a drain, check and temporarily disconnect the following components: </li></ul><ul><ul><li>Light under the hood (Some lights under the hood are hot all the time and light by means of a mercury switch when the hood is opened.) </li></ul></ul><ul><ul><li>Glove compartment light </li></ul></ul><ul><ul><li>Trunk light </li></ul></ul>(Continued)
  64. 65. <ul><li>If after disconnecting these components, the battery drain can still light the test light or draws more than 50 mA (0.05 A), disconnect one fuse at a time from the fuse box until the test light goes out or the ammeter reading drops. </li></ul>(Continued)
  65. 66. <ul><li>If the drain drops to normal after one fuse is disconnected, the source of the drain is located in that particular circuit, as labeled on the fuse box. Continue to disconnect the power-side wire connectors from each component included in that particular circuit until the ammeter reads a normal amount of draw. </li></ul>(Continued)
  66. 67. <ul><li>The source of the battery drain can then be traced to an individual component or part of one circuit. </li></ul><ul><li>To help avoid disconnecting a battery, yet still perform a battery drain test, construct a simple cigarette lighter plug and lantern battery hookup </li></ul>(Continued)
  67. 68. <ul><li>Use a Voltmeter in the Place of an Ammeter </li></ul><ul><ul><li>Some DMMs do not measure amperes. To accurately measure battery electrical drain, connect the digital meter set to read DC volts across the ends of a 1-ohm, 10-watt resistor connected in series with the disconnected negative battery cable. </li></ul></ul>(Continued)
  68. 69. <ul><ul><li>If 0.02 A flows through a 1-ohm resistor, the voltage will drop 0.02 volt (E = I X R; 0.02 A X 1 Ω = 0.02 volt). The voltmeter reads the voltage drop across the 1-ohm resistor and the voltage reading is equal to the amperage flowing through the 1-ohm resistor. </li></ul></ul>(Continued)
  69. 70. Figure 9-18 Measuring battery electrical drain using a multimeter set to read DC amperes. (Courtesy of Fluke Corporation)
  70. 71. Figure 9-19 This mini clamp-on DMM is being used to measure the amount of battery electrical drain that is present. In this case, a reading of 20 mA (displayed on the meter as 00.02 A) is within the normal range of 20 to 30 mA. Be sure to clamp around all of the positive battery cable or all of the negative battery cable, whichever is easiest to clamp.
  71. 72. Figure 9-20 After connecting the shutoff tool, start the engine and operate all accessories. Stop the engine and turn off everything. Connect the ammeter across the shutoff switch in parallel. Wait 20 minutes. This time allows all electronic circuits to “time out” or shut down. Open the switch - all current now will flow through the ammeter. A reading greater than specified, usually greater than 50mA (0.05A), indicates a problem that should be corrected.
  72. 73. Figure 9-21 The battery was replaced in this Acura and the radio displayed “code” when the replacement battery was installed. Thankfully, the owner had the five-digit code required to unlock the radio.
  73. 74. Figure 9-22 Here is a clever tool that can be easily built. It combines a memory saver and a battery electrical drain tester in one. By connecting the alligator clips, the lighter plug can be inserted into the lighter receptacle to keep the computer and radio memory alive. To measure battery electrical drain without having to disconnect electrical power, simply connect the alligator clip to the leads of a digital multimeter set on the ampere setting with the leads correctly inserted in the meter as shown. Disconnect the negative battery cable and read the battery electrical drain directly on the meter face. When testing is complete, simply reattach the battery cable and disconnect the lighter plug. (Courtesy of Fluke Corporation)
  74. 75. Figure 9-23 Amperes-to-volts converter.
  75. 76. Figure 9-24 A voltmeter can be used to measure amperes because the voltage drop across a 1-ohm resistor is the same as the current flowing through the resistor (E 5 I x R; E 5 0.02 A x 1 ohm 5 0.02 volt). In this case, 0.02 A is flowing through the 1-ohm resistor. According to Ohm’s law, this amount of current creates a voltage drop of 0.02 volt; therefore, this tool is sometimes called an amp-to-volt converter.
  76. 77. CRANKING CIRCUIT <ul><li>Circuits include the following: </li></ul><ul><ul><li>Starter motor. </li></ul></ul><ul><ul><li>Battery. </li></ul></ul><ul><ul><li>Starter solenoid or relay. </li></ul></ul><ul><ul><li>Starter drive. </li></ul></ul><ul><ul><li>Ignition switch. </li></ul></ul>(Continued)
  77. 78. <ul><li>Many automobile manufacturers use an electric switch, called a neutral safety switch (part of the transmission range switch), which opens the circuit between the ignition switch and the starter to prevent starter motor operation outside of neutral or park. </li></ul>(Continued)
  78. 79. Figure 9-25 Adjustment location for a typical steering column-mounted ignition switch. This style of ignition switch is mounted on top of the steering column behind the dash panel and operated by a rod from the key switch.
  79. 80. Figure 9-26 The ignition switch on some vehicles is part of the lock mechanism. The ignition switch assembly has been removed from this Chevrolet Blazer’s attachment location just to the right of the steering column.
  80. 81. Figure 9-27 Typical solenoid-operated starter installation.
  81. 82. DIAGNOSING STARTER PROBLEMS USING VISUAL INSPECTION <ul><li>The following should be carefully checked as part of a thorough visual inspection: </li></ul><ul><ul><li>Carefully check the battery cables for tightness. </li></ul></ul><ul><ul><li>Check if the heat shield (if equipped) is still in place. </li></ul></ul>(Continued)
  82. 83. <ul><ul><li>Check for any nonstock add-on accessories or equipment that may drain the battery such as a sound system, or extra lighting. </li></ul></ul><ul><ul><li>Crank the engine. Feel the battery cables and connections. If any cables or connections are hot to the touch, then an excessive voltage drop or a defective starter that is draining too much current is the cause. </li></ul></ul>(Continued)
  83. 84. Figure 9-28 Carefully inspect all battery terminals for corrosion. This vehicle uses two positive battery cables connected at the battery using a long bolt. This is a common source of corrosion that can cause a starting (cranking) problem.
  84. 85. STARTER TESTING ON THE VEHICLE <ul><li>A starter amperage test should be performed when the starter fails to operate normally (is slow in cranking) or as part of a routine electrical system inspection. </li></ul>(Continued)
  85. 86. <ul><li>If exact specifications are not available, the following can be used as general specifications for testing a starter on the vehicle: </li></ul><ul><ul><li>Four-cylinder engines = 150 to 185 A maximum reading </li></ul></ul><ul><ul><li>Six-cylinder engines = 160 to 200 A maximum reading </li></ul></ul><ul><ul><li>Eight-cylinder engines = 185 to 250 A maximum reading </li></ul></ul>(Continued)
  86. 87. <ul><li>Excessive current draw may indicate one or more of the following: </li></ul><ul><ul><li>Binding of starter armature as a result of worn bushings </li></ul></ul><ul><ul><li>Oil too thick (viscosity too high) for weather conditions </li></ul></ul><ul><ul><li>Shorted or grounded starter windings or cables </li></ul></ul><ul><ul><li>Tight or seized engine </li></ul></ul>(Continued)
  87. 88. Figure 9-29 A simple, low-cost handheld inductive ammeter can be used to measure starter amperage draw. Although not always accurate, it does give the service technician an indication of the amount of current flowing through either the positive or the negative cable while the engine is being cranked.
  88. 89. Figure 9-30 When connecting a starter tester such as a SUN VAT-40 to the vehicle, ensure that the inductive probe is placed over all of the cables or wires from either the positive or the negative post of the cable. Remember, the same amount of current (amperes) must return to the battery negative terminal as left the positive terminal at the battery.
  89. 90. Figure 9-31 Low battery voltage, as indicated here on a Fluke Scopemeter, will cause the inaccurate starter motor testing results. For best results, the battery should be at least 75% charged (12.4 volts or higher).
  90. 91. Figure 9-32 Use a DMM and an optional amp probe to measure starter current draw. (Courtesy of Fluke Corporation)
  91. 92. TESTING A STARTER USING A SCAN TOOL <ul><li>Follow these steps: </li></ul><ul><ul><li>Connect the scan tool according to the manufacturer’s instructions. </li></ul></ul><ul><ul><li>Select battery voltage and engine RPM on the scan tool. </li></ul></ul><ul><ul><li>Select “snapshot” and start recording. </li></ul></ul><ul><ul><li>Crank the engine. Stop the scan tool recording. </li></ul></ul>(Continued)
  92. 93. <ul><ul><li>Retrieve the scan data and record cranking RPM and battery voltage during cranking. Cranking RPM should be between 80 and 250 RPM. Battery voltage during cranking should be higher than 9.6 volts. </li></ul></ul>
  93. 94. VOLTAGE-DROP TESTING <ul><li>Voltage drop is the drop in voltage that occurs when current is flowing through a resistance. </li></ul>(Continued)
  94. 95. <ul><li>A high voltage drop (high resistance) in the cranking circuit wiring can cause slow engine cranking with less-than-normal starter amperage drain as a result of the excessive circuit resistance. If the voltage drop is high enough, such as could be caused by dirty battery terminals, the starter may not operate. </li></ul>(Continued)
  95. 96. <ul><li>A typical symptom of high resistance in the cranking circuit is a &quot;clicking&quot; of the starter solenoid. </li></ul><ul><li>Voltage-drop testing of the wire involves connecting any voltmeter (on the low scale) to the suspected high-resistance cable ends and cranking the engine. </li></ul>(Continued)
  96. 97. <ul><li>NOTE: Before a difference in voltage (voltage drop) can be measured between the ends of a battery cable, current must be flowing through the cable. Resistance is ineffective unless current is flowing. If the engine is not being cranked, current is not flowing through the battery cables and the voltage drop cannot be measured. </li></ul>(Continued)
  97. 98. <ul><li>If the difference in the two readings exceeds 0.5 volt, perform the following steps to determine the exact location of the voltage drop. </li></ul><ul><ul><li>Connect the red voltmeter test lead to the most positive end of the cable being tested. The most positive end of a cable is the end closest to the positive terminal of the battery. </li></ul></ul>(Continued)
  98. 99. <ul><ul><li>Connect the black voltmeter test lead to the other end of the cable being tested. With no current flowing through the cable, the voltmeter should read zero because there is the same voltage at both ends of the cable. </li></ul></ul><ul><ul><li>Crank the engine. The voltmeter should read less than 0.2 volt. </li></ul></ul>(Continued)
  99. 100. <ul><ul><li>Evaluate the results. If the voltmeter reads zero, the cable being tested has no resistance and is good. If the voltmeter reads higher than 0.2 volt, the cable has excessive resistance and should be replaced. </li></ul></ul>(Continued)
  100. 101. Figure 9-33 A typical Ford solenoid on the left; a typical GM solenoid on the right.
  101. 102. Figure 9-34 Voltmeter hookups for voltage-drop testing of a GM-type cranking circuit.
  102. 103. Figure 9-35 Voltmeter hookups for voltage-drop testing of a Ford-type cranking circuit.
  103. 104. Figure 9-36 Voltmeter hookups for voltage-drop testing of a Chrysler brand type cranking circuit.
  104. 105. Figure 9-37 Using the voltmeter leads from a starting and charging test unit to measure the voltage drop between the battery terminal (red lead) and the cable end (black lead). The engine must be cranked to cause current to flow through this connection.
  105. 106. Figure 9-38 To measure voltage drop, the engine must be cranking so that current flows—111 mV is equal to 0.111 volt. Vehicle manufacturers would allow between 200 and 400 mV voltage drop in the battery cables. (Courtesy of Fluke Corporation)
  106. 107. Figure 9-39 Using the “touch hold” feature of the meter allows a service technician to test circuits without the use of an assistant. (Courtesy of Fluke Corporation)
  107. 108. Figure 9-40 Starter diagnosis chart.
  108. 109. STARTER DRIVE-TO-FLYWHEEL CLEARANCE <ul><li>For the 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. Many starters use shims (thin metal strips) between the flywheel and the engine block mounting pad to provide the proper clearance. </li></ul>(Continued)
  109. 110. <ul><li>If the clearance is too great, the starter will produce a high-pitched whine during cranking. 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. </li></ul>(Continued)
  110. 111. <ul><li>To ensure that the starter is shimmed correctly, use the following procedure: </li></ul><ul><ul><li>Step 1: Place the starter in position and finger-tighten the mounting bolts. </li></ul></ul><ul><ul><li>Step 2: Use an 1/8-in.-diameter drill bit (or gauge tool) and insert between the armature shaft and a tooth of the engine flywheel. </li></ul></ul>(Continued)
  111. 112. <ul><ul><li>Step 3: If the gauge tool cannot be inserted, use a full-length shim across both mounting holes, which moves the starter away from the flywheel. </li></ul></ul><ul><ul><li>Step 4 : Remove a shim or shims if the gauge tool is loose between the shaft and the tooth of the engine flywheel. </li></ul></ul>(Continued)
  112. 113. <ul><ul><li>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. </li></ul></ul>(Continued)
  113. 114. Figure 9-41 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.
  114. 115. HOW A GENERATOR WORKS <ul><li>A rotor inside a generator (alternator) is turned by a belt and drive pulley, which are turned by the engine. The magnetic field of the rotor generates a current in the windings of the stator by electromagnetic induction. </li></ul>(Continued)
  115. 116. <ul><li>Field current flowing through the slip rings to the rotor creates an alternating north and south pole on the rotor, with a magnetic field between each finger of the rotor. The induced current in the stator windings is an alternating current because of the alternating magnetic field of the rotor. </li></ul>(Continued)
  116. 117. <ul><li>The induced current starts to increase as the magnetic field starts to induce current in each winding of the stator. The current then peaks when the magnetic field is the strongest and starts to decrease as the magnetic field moves away from the stator winding. Therefore, the current generated is described as being of a sine wave pattern. </li></ul>(Continued)
  117. 118. <ul><li>As the rotor continues to rotate, this sine wave current is induced in each of the three windings of the stator. </li></ul><ul><li>Because each of the three windings generates a sine wave current, the resulting currents combine to form a three-phase voltage output. </li></ul>(Continued)
  118. 119. <ul><li>The resulting currents combine to form a three-phase voltage output. </li></ul><ul><li>Two methods used to connect the stator winding to the output terminal. </li></ul>(Continued)
  119. 120. Figure 9-42 Rotor assembly of a typical AC generator (alternator). Current through the slip rings causes the “fingers” of the rotor to become alternating north and south magnetic poles. As the rotor revolves, these magnetic lines of force induce a current in the stator windings.
  120. 121. Figure 9-43 Magnetic lines of force cutting across a conductor induce a voltage and current in the conductor.
  121. 122. Figure 9-44 Sine wave voltage curve created by one revolution of a winding that is rotating in a magnetic field.
  122. 123. Figure 9-45 When three windings (A, B, and C) are present in a stator, the resulting current generation is represented by the three sine waves. The voltages are 120 degrees out of phase. The connection of the individual phases produces a three-phase alternating voltage.
  123. 124. Figure 9-46 Wye-connected stator winding.
  124. 125. Figure 9-47 Delta-connected stator winding.
  125. 126. GENERATOR CONSTRUCTION <ul><li>A generator is constructed of a two-piece cast aluminum housing. Aluminum is used because of its lightweight, nonmagnetic properties, and heat transfer properties which are needed to help keep the generator cool. </li></ul>(Continued)
  126. 127. <ul><li>A front ball bearing is pressed into the front housing (called the drive-end [DE] housing ) to provide the support and friction reduction necessary for the belt-driven rotor assembly. The rear housing, called the slip ring end (SRE) , usually contains a roller-bearing support for the rotor and mounting for the brushes, diodes, and internal voltage regulator </li></ul>(Continued)
  127. 128. Figure 9-48 Cutaway view of a typical AC generator (alternator).
  128. 129. CHECKING CHARGING SYSTEM VOLTAGE <ul><li>To measure charging system voltage, connect the test leads of a DMM to the positive and negative terminals of the battery. Set the multimeter to read DC volts. </li></ul>(Continued)
  129. 130. <ul><li>Most generators are designed to supply between 13.5 and 15.0 volts at 2000 engine RPM. Be sure to check the vehicle manufacturer’s specifications. For example, most General Motors Corporation vehicles specify a charging voltage of 14.7 volts ± 0.5 (or between 14.2 and 15.2 volts). </li></ul>(Continued)
  130. 131. <ul><li>To measure charging system voltage, take the following steps: </li></ul><ul><ul><li>Connect the voltmeter </li></ul></ul><ul><ul><li>Set the meter to read DC volts. </li></ul></ul><ul><ul><li>Start the engine and raise to a fast idle (about 2000 RPM). </li></ul></ul>(Continued)
  131. 132. <ul><ul><li>Read the voltmeter and compare with specifications. If lower than specifications, charge the battery and test for excessive charging circuit voltage drop before replacing the generator. </li></ul></ul>(Continued)
  132. 133. <ul><li>The Lighter Plug Trick </li></ul><ul><ul><li>Battery voltage measurements can be read through the lighter socket. </li></ul></ul><ul><li>A scan tool can be used on most vehicles that have data stream information. Follow these steps: </li></ul><ul><ul><li>Connect the scan tool according to the manufacturer’s instructions. </li></ul></ul><ul><ul><li>Select battery voltage and engine RPM on the scan tool. </li></ul></ul>(Continued)
  133. 134. <ul><ul><li>Start the engine and operate at 2000 RPM. </li></ul></ul><ul><ul><li>Observe the battery voltage. This voltage should be between 13.5 and 15.0 volts (or within the manufacturer’s specifications). </li></ul></ul>(Continued)
  134. 135. Figure 9-49 The DMM should be set to read DC volts and the red lead connected to the battery positive (1) terminal and the black meter lead connected to the negative (2) battery terminal.
  135. 136. Figure 9-50 (a) A simple and easy-to-use tester can be made from a lighter plug and double banana plug that fits the COM and V terminals of most digital meters. A
  136. 137. Figure 9-50 (continued) (b) By plugging the lighter plug into the lighter, the charging circuit voltage can be easily measured. B
  137. 138. AC RIPPLE VOLTAGE CHECK <ul><li>A good generator should produce little AC voltage. </li></ul><ul><li>It is the purpose of the diodes in the generator to rectify all AC voltage into DC voltage. The procedure to check for AC ripple voltage includes the following steps: </li></ul>(Continued)
  138. 139. <ul><ul><li>Set the digital meter to read AC volts. </li></ul></ul><ul><ul><li>Start the engine and operate it at 2000 RPM (fast idle). </li></ul></ul><ul><ul><li>Connect the voltmeter leads to the positive and negative battery terminals. </li></ul></ul><ul><ul><li>Turn on the headlights to provide an electrical load on the generator. </li></ul></ul><ul><ul><li>A higher, more accurate reading can be obtained by touching the meter lead to the output terminal of the generator </li></ul></ul>(Continued)
  139. 140. <ul><li>The results should be interpreted as follows: If the diodes are good, the voltmeter should read less than 0.4 volt AC. If the reading is over 0.5 volt AC, the rectifier diodes are defective. </li></ul><ul><ul><li>NOTE: This test will not test for a defective diode trio. </li></ul></ul>(Continued)
  140. 141. <ul><li>The amount of AC current in amperes flowing from the generator to the battery can be measured using a clamp-on DMM set to read AC amperes. Attach the clamp of the meter around the generator output wire or all of the positive or negative battery cables if the output wire is not accessible. </li></ul>(Continued)
  141. 142. Figure 9-54 A mini clamp-on DMM can be used to measure generator output. This meter was set on the 200-A DC scale. With the engine running and all lights and accessories on, the generator was able to produce almost exactly its specified rating of 105A. Switching the clamp-on meter to AC amperes will allow the technician to check for defective diodes.
  142. 143. Figure 9-55 Any DMM can be turned into a high-amperage measuring instrument by attaching an AC/DC current clamp adapter to the meter and reading the amperage on the DC millivolt scale.
  143. 144. <ul><li>Start the engine and turn on all lights and accessories to load the generator and read the meter display. The maximum allowable AC amperes from the generator should be less than 10% of the rated output of the generator. </li></ul>(Continued)
  144. 145. <ul><li>For example, if the alternator is producing 100 A, the maximum allowable AC amperes would be 10 A. If the reading is above 10 A (or 10%), there is a fault with the rectifier diodes or with the stator windings. </li></ul>(Continued)
  145. 146. Figure 9-51 AC ripple at the output terminal of the battery is more accurate than testing at the battery due to the resistance of the wiring between the generator and the battery. The reading shown on the meter is only 78 mV (0.078 volt), far below what the reading would be if a diode were defective. (Courtesy of Fluke Corporation)
  146. 147. Figure 9-52 Generator ripple is a small amount of AC riding on the DC output. AC level above 500 mV indicates diode trouble. This illustration shows a normal waveform. To capture this waveform, a low pass filter was used to reduce noise. (Courtesy of Fluke Corporation)
  147. 148. Figure 9-53 To test for a possible defective diode, disconnect the generator output cable from the generator and test using the procedure shown. (Courtesy of Fluke Corporation)
  148. 149. CHARGING SYSTEM VOLTAGE-DROP TESTING <ul><li>For the proper operation of any charging system, there must be good electrical connections between the battery positive terminal and the generator output terminal. The generator must also be properly grounded to the engine block. </li></ul>(Continued)
  149. 150. <ul><li>Measure the voltage drop of the insulated (power-side) charging circuit: </li></ul><ul><ul><li>Start the engine and run it at a fast idle (about 2000 engine RPM). </li></ul></ul><ul><ul><li>Turn on the headlights to ensure an electrical load on the charging system. </li></ul></ul>(Continued)
  150. 151. <ul><ul><li>Using any voltmeter, connect the positive test lead (usually red) to the output terminal of the generator. Attach the negative test lead (usually black) to the positive post of the battery. </li></ul></ul>(Continued)
  151. 152. Figure 9-56 Voltmeter hookup to test the voltage drop of the charging circuit.
  152. 153. <ul><li>The results should be interpreted as follows: </li></ul><ul><ul><li>If there is less than a 0.4 volt reading, then all wiring and connections are satisfactory. </li></ul></ul><ul><ul><li>If the voltmeter reads higher than 0.4 volt, there is excessive resistance (voltage drop) between the generator output terminal and the positive terminal of the battery. </li></ul></ul>(Continued)
  153. 154. <ul><ul><li>If the voltmeter reads battery voltage (or close to battery voltage), there is an open circuit between the battery and the generator output terminal. </li></ul></ul><ul><ul><li>To determine if the generator is correctly grounded, maintain the engine speed at 2000 RPM with the headlights on. Connect the positive voltmeter lead to the case of the generator and the negative voltmeter lead to the negative terminal of the battery. </li></ul></ul>(Continued)
  154. 155. <ul><ul><li>The voltmeter should read less than 0.2 volt if the generator is properly grounded. If the reading is over 0.2 volt, connect one end of an auxiliary ground wire to the case of the generator and the other end to a good engine ground. </li></ul></ul>(Continued)
  155. 156. Figure 9-57 A diagram showing the location of the charging system wiring of a typical vehicle. The best location to check for the generator (alternator) output is at the output wire from the B+ (BAT) terminal. Notice that the generator supplies all electrical needs of the vehicle first, then charges the battery if needed.
  156. 157. GENERATOR OUTPUT TEST <ul><li>If in doubt about charging system output, first check the condition of the generator drive belt. With the engine off, attempt to rotate the fan of the generator by hand. </li></ul><ul><li>The testing procedure for generator output is as follows: </li></ul><ul><ul><li>Connect the starting and charging test leads according to the manufacturer’s instructions. </li></ul></ul>(Continued)
  157. 158. <ul><ul><li>Turn the ignition switch on (engine off) and observe the ammeter. This reading is the ignition circuit current, and should be 2 to 8 A. </li></ul></ul><ul><ul><li>NOTE: If possible, attach the ammeter inductive probe around the generator output cable. This eliminates the need to add the ignition-on current to the reading at the battery cable. When the inductive probe is placed around the output wire of the generator, the ammeter will read the output directly. </li></ul></ul>(Continued)
  158. 159. <ul><ul><li>Start the engine and operate it at 2000 RPM (fast idle). Turn the load increase control slowly to obtain the highest reading on the ammeter scale. Note the ampere reading. </li></ul></ul><ul><ul><li>Total the amperes from steps 2 and 3. Results should be within 10% (or 15 A) of the rated output. Rated output may be stamped on the generator </li></ul></ul>(Continued)
  159. 160. <ul><ul><li>If the generator output is less than within 10% of its rated output, repeat the test, but now bypass the voltage regulator and provide a full-field current to the rotor (field) of the generator. </li></ul></ul>(Continued)
  160. 161. <ul><li>Almost all vehicle manufacturers are now using some load response control (LRC), or electronic load detector (ELD), in the control of the voltage output (voltage regulator) of the generator. Thus, the regulator does not react immediately to a load change, but rather slowly increases the load on the generator to avoid engine idle problems. </li></ul>(Continued)
  161. 162. <ul><ul><li>This gradual increase of voltage may require as long as 15 seconds. This delay has convinced some technicians that a problem exists in the generator/regulator or computer control of the generator. </li></ul></ul><ul><ul><li>NOTE: When applying a load to the battery with a carbon pile tester during a generator output test, do not permit the battery voltage to drop below 12 volts. Most generators will produce their maximum output (in amperes) above 13 volts. </li></ul></ul>(Continued)
  162. 163. Figure 9-58 Typical hookup of a starting and charging tester.
  163. 164. Figure 9-59 The amperage rating of most GM generators is stamped on the drive-end housing either facing the front (pulley side) or on top behind the small threaded mounting lug.
  164. 165. HOW TO DETERMINE MINIMUM GENERATOR OUTPUT <ul><li>When the generator output specification is unknown, the technician can use three methods to check for proper generator output. </li></ul><ul><ul><li>Method 1 Find the rating of the charging system fuse. Most fuses adhere to the 80% rule which states that the maximum current of the circuit should equal 80% of the fuse rating. </li></ul></ul>(Continued)
  165. 166. <ul><ul><li>Method 2 Connect an inductive ammeter such as a VAT-40 or equal to the battery cables. Be sure the inductive amperage probe is around all the positive (or negative) wires. </li></ul></ul><ul><ul><li>Turn on every electrical component, including: </li></ul></ul><ul><ul><ul><li>Headlights (on bright) </li></ul></ul></ul><ul><ul><ul><li>Radio </li></ul></ul></ul><ul><ul><ul><li>Windshield wipers (on high) </li></ul></ul></ul>(Continued)
  166. 167. <ul><ul><ul><li>Air conditioning (blower on high) </li></ul></ul></ul><ul><ul><ul><li>Rear window defogger </li></ul></ul></ul><ul><ul><ul><li>Turn signal </li></ul></ul></ul><ul><ul><ul><li>Read the ammeter. Add 5 A. This amount represents the minimum amperage output required. </li></ul></ul></ul>(Continued)
  167. 168. <ul><ul><li>Method 3 Similar to method 2, except this method reads the difference between the generator output and the electrical load directly. Connect an ammeter such as a VAT-40 to the battery cables as instructed previously. Start the engine and operate at 2000 RPM while turning on the items listed in method 2. Read the ammeter. </li></ul></ul>(Continued)
  168. 169. <ul><ul><li>The ammeter should read at least 5 A of charging current. This means that the generator (charging system) is capable of producing all the electrical needs of the vehicle and is still able to recharge the battery. </li></ul></ul>(Continued)
  169. 170. Figure 9-60 The fusible link (or fuse) rating for the charging circuit should be greater than the generator output by 20%. Therefore, the maximum generator output should be 80% of the fuse rating or 64 A.
  170. 171. Figure 9-61 When connecting an inductive ammeter probe, ensure that the pickup is over all wires. The probe will work equally well over either all positive or all negative cables, because all current leaving a battery must return.
  171. 172. Figure 9-62 The inductive pickup displays the actual charging system amperage output on the digital meter face set to read millivolt (mV). The reading of 062.0 mV on the display means the generator is charging 62 A. (Courtesy of Fluke Corporation)
  172. 173. TESTING A GENERATOR USING A SCOPE <ul><li>Defective diodes and open or shorted stators can be detected on a scope. </li></ul><ul><li>If the ripple pattern is jagged or uneven, a defective diode (open or shorted) or a defective stator is indicated. </li></ul>(Continued)
  173. 174. <ul><li>Magnetized Rear-Bearing Trick </li></ul><ul><ul><li>When diagnosing a no-charge complaint, use a screwdriver (or other steel object) and check if the rear bearing is magnetized on the generator with the engine running and the lights on. </li></ul></ul>(Continued)
  174. 175. <ul><li>If the rear bearing is magnetized, then the following facts are known: </li></ul><ul><ul><li>The voltage regulator is working. </li></ul></ul><ul><ul><li>The generator brushes are working. </li></ul></ul><ul><ul><li>The rotor in the generator is producing a magnetic field. </li></ul></ul>(Continued)
  175. 176. <ul><li>If the rear bearing is not magnetized, then one or more of the following problems exist: </li></ul><ul><ul><li>The voltage regulator is not working. </li></ul></ul><ul><ul><li>The generator brushes are worn or stuck, and they are not making good electrical contact with the rotor slip rings. </li></ul></ul><ul><ul><li>The generator rotor is defective. </li></ul></ul>(Continued)
  176. 177. Figure 9-63 Normal generator scope pattern. This AC ripple is on top of a DC voltage line. The ripple should be less than 0.50 volt high.
  177. 178. Figure 9-64 Generator pattern indicating a shorted diode.
  178. 179. Figure 9-65 Generator pattern indicating an open diode.
  179. 180. Figure 9-66 Generator ripple displayed on a DSO. (Courtesy of Fluke Corporation)
  180. 181. Figure 9-67 If the rear bearing is magnetized, the voltage regulator, generator brushes, and rotor are functioning.

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