AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING

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Electrical problems drawing current out of the battery with the ignition OFF defective battery can be found by using a hydrometerto check each cell. If the specific gravity in any cell varies excessively from other cells (25 to 50 points), the battery is bad. Cells with low readings may be shorted. When all of the cells have equal specific gravity, even if they are low, the battery can usually be recharged. On maintenance-free batteries a charge indicator eye shows the battery charge. The charge indicator changes color with levels of battery charge. For example, the indicator may be green with the battery fully charged. It may turn black when discharged or yellow when the battery needs to be replaced. If there is no charge indicator eye or when in doubt of its reliability, a voltmeter and ammeter or a load tester can also be used to determine battery condition quickly. BATTERY TEST As a mechanic you will be expected to test batteries for proper operation and condition. These tests are as follows: Battery leakage test Battery terminal test Battery voltage test Cell voltage test Battery drain test Battery load test (battery capacity test) Quick charge test BATTERY LEAKAGE TEST.- A battery leakage test will determine if current is discharging across the top of the battery. A dirty battery can discharge when not in use. This condition shortens battery life and causes starting problems. To perform a battery leakage test, set a voltmeter on a low setting. Touch the probes on the battery, as shown in figure 2-6. If any current is registered on the voltmeter, the top of the battery needs to be cleaned. BATTERY TERMINAL TEST.- The battery terminal test quickly checks for poor electrical connection between the terminals and the battery cables. A voltmeter is used to measure voltage drop across terminals and cables. To perform a battery terminal test (fig. 2-7), connect the negative voltmeter lead to the battery cable end. Touch the positive lead to the battery terminal. With the ignition or injection system disabled so that the engine will not start, crank the engine while watching the voltmeter reading. AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING 16/ 101
Figure 2-6.- Battery leakage test. Figure 2-7.- Battery terminal test. If the voltmeter reading is .5 volts or above, there is high resistance at the battery cable connection. This indicates that the battery connections need to be cleaned. A good, clean battery will have less than a .5 volt drop. BATTERY VOLTAGE TEST.- The battery voltage test is done by measuring total battery voltage with an accurate voltmeter or a special battery tester (fig. 2-8). This test determines the general state of charge and battery condition quickly. The battery voltage test is used on maintenance-free batteries because these batteries do not have caps that can be removed for testing with a hydrometer. To perform this test, connect the voltmeter or battery tester across the battery terminals. Turn on the vehicle headlights or heater blower to provide a light load. Now read the meter or tester. A well-charged battery should have over 12 volts. If the meter reads approximately 11.5 volts, the battery is not charged adequately, or it may be defective. AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING 17/ 101
Page 1 and 2: AUTOMOTIVE ELECTRICAL CIRCUITS AND
Page 3 and 4: AUTOMOTIVE ELECTRICAL CIRCUITS AND
Page 5 and 6: It must help the charging system pr
Page 7 and 8: BATTERY CASE, COYER, AND CAPS. The
Page 9 and 10: BATTERY CAPACITY The capacity of a
Page 11 and 12: smaller charge is needed. As the ba
Page 13 and 14: the water slowly, stirring gently b
Page 15: the terminals just enough to secure
Page 19 and 20: To perform a battery drain test, se
Page 21 and 22: must be used to convert from altern
Page 23 and 24: charge, the line voltage will incre
Page 25 and 26: Figure 2-14.- Schematic wiring diag
Page 27 and 28: short is present, the steel strip w
Page 29 and 30: Figure 2-20.- Testing an armature f
Page 31 and 32: The fingers on one of the claw-shap
Page 33 and 34: A cross-sectional view of a typical
Page 35 and 36: The electronic voltage regulators u
Page 37 and 38: If the ohmmeter reading is low or t
Page 39 and 40: After completing the required test
Page 41 and 42: CAUTION Follow the manufacturer's d
Page 43 and 44: armature and the field; the attract
Page 45 and 46: gears engage and when the engine ki
Page 47 and 48: voltage from the battery is often t
Page 49 and 50: eduction drive head may rotate as m
Page 51 and 52: Once the starter is checked and rep
Page 53 and 54: The ignition circuit is actually ma
Page 55 and 56: Figure 2-43.- Ignition switch and p
Page 57 and 58: DISTRIBUTOR CAP.- The distributor c
Page 59 and 60: SPARK PLUG WIRES The spark plug wir
Page 61 and 62: The components of an electronic ign
Page 63 and 64: As speed increases, centrifugal for
Page 65 and 66: Spark Plugs and Spark Plug Wires Ba
Page 67 and 68:
Figure 2-50.- Ash fouled. When a sp
Page 69 and 70:
A common problem arises when a CARB
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ELECTRONIC IGNITION DISTRIBUTOR SER
Page 73 and 74:
After the initial ignition timing,
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Figure 2-56.-( A) Single-contact bu
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Figure 2-60.- Blackout light/ headl
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To ensure that the headlights are p
Page 81 and 82:
Figure 2-65.- Blackout driving ligh
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The turn signal flasher unit (fig.
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EMERGENCY LIGHT SYSTEM The emergenc
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operation, the voltage indicated on
Page 89 and 90:
The THERMOSTATIC FUEL GAUGE, SELF-R
Page 91 and 92:
A pressure gauge is used widely in
Page 93 and 94:
Figure 2-82.- Types of sending unit
Page 95 and 96:
Electronic Speedometers and Tachome
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AUTOMOTIVE WIRING Learning Objectiv
Page 99 and 100:
Figure 2-86.- A typical wiring harn
Page 101:
Figure 2-89.- Wiring diagram symbol
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AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING

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