AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING

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Figure 2-70.- Turn signal flasher. The backup light switch closes the light circuit when the transmission is shifted into reverse. The most common backup light switch configurations are as follows: The backup light switch mounted on the transmission and operated by the shift lever. The backup light switch mounted on the steering column and operated by the gearshift linkage. The transmission-or gearshift-mounted backup light switch on many automatic transmission- STOPLIGHT SYSTEM All vehicles that are used on public highways must be equipped with a stoplight system. The stoplight system consists of a fuse, brake light switch (fig. 2-71), two rear warning lights, and related wiring. The brake light switch on most automotive equipment is mounted on the brake pedal. When the brake pedal is pressed, it closes the switch and turns on the rear brake lights. On construction and tactical equipment, you may find a pressure light switch. This type of switch uses either air or hydraulic pressure, depending on the equipment. It is mounted on the master cylinder of the hydraulic brake system or is attached to the brake valve on an air brake system. As the brakes are depressed, either air or hydraulic pressure builds on a diaphragm inside the switch. The diaphragm closes allowing electrical current to turn on the rear brake lights. AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING 84/ 101
EMERGENCY LIGHT SYSTEM The emergency light system, also termed hazard warning system, is designed to signal oncoming traffic that a vehicle has stopped, stalled, or has pulled up to the side of the road. The system consists of a switch, flasher unit, four turn signal lights, and related wiring. The switch is normally a push-pull switch and is mounted on the steering column. When the switch is closed, current flows through the emergency flasher. Like a turn signal flasher, the emergency flasher opens and closes the circuit to the lights. This causes all four turn signals to flash. Figure 2-71.- Brake light switches. CIRCUIT BREAKERS AND FUSES Fuses are safety devices placed in electrical circuits to protect wires and electrical units from a heavy flow of current. Each circuit, or at least each individual electrical system, is provided with a fuse that has an ampere rating for the maximum current required to operate the units. The fuse element is made from metal with a low-melting point and forms the weakest point of the electrical circuit. In case of a short circuit or other trouble, the fuse will be burned out first and open the circuit just as a switch would do. Examination of a burnt-out fuse usually gives an indication of the problem. A discolored sight glass indicates the circuit has a short either in the wiring or in one of its components. If the glass is clear, the problem is an overloaded circuit. Be sure when replacing a fuse that it has a rating equal to the one burned out. Ensure that the trouble of the failure has been found and repaired. A circuit breaker performs the same function as a fuse. It disconnects the power source from the circuit when current becomes too high. The circuit breaker will remain open until the trouble is corrected. Once the trouble is corrected, a circuit breaker will automatically reset itself when current returns to normal levels. The fuses and circuit breakers can usually be found behind the instrument panel on a fuse block (fig. 2-72). AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING 85/ 101
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AUTOMOTIVE ELECTRICAL CIRCUITS AND
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AUTOMOTIVE ELECTRICAL CIRCUITS AND
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It must help the charging system pr
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BATTERY CASE, COYER, AND CAPS. The
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BATTERY CAPACITY The capacity of a
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smaller charge is needed. As the ba
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the water slowly, stirring gently b
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the terminals just enough to secure
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Figure 2-6.- Battery leakage test.
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To perform a battery drain test, se
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must be used to convert from altern
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charge, the line voltage will incre
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Figure 2-14.- Schematic wiring diag
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short is present, the steel strip w
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Figure 2-20.- Testing an armature f
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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
Page 71 and 72: ELECTRONIC IGNITION DISTRIBUTOR SER
Page 73 and 74: After the initial ignition timing,
Page 75 and 76: Figure 2-56.-( A) Single-contact bu
Page 77 and 78: Figure 2-60.- Blackout light/ headl
Page 79 and 80: To ensure that the headlights are p
Page 81 and 82: Figure 2-65.- Blackout driving ligh
Page 83: The turn signal flasher unit (fig.
Page 87 and 88: 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
Page 97 and 98: 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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