AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING

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Figure 2-35.- Typical insulated resistance test setup. Figure 2-36.- Typical ground circuit resistance test setup. STARTING CIRCUIT Learning Objective: Identify starting-circuit components, their function, operation, and maintenance procedures. The internal combustion engine is not capable of self-starting. Automotive engines (both spark-ignition and diesel) are cranked by a small but powerful electric motor. This motor is called a cranking motor, starting motor, or starter. The battery sends current to the starter when the operator turns the ignition switch to start. This causes a pinion gear in the starter to mesh with the teeth of the ring gear, thereby rotating the engine crankshaft for starting. The typical starting circuit consists of the battery, the starter motor and drive mechanism, the ignition switch, the starter relay or solenoid, a neutral safety switch (automatic transmissions), and the wiring to connect these components. STARTER MOTOR The starting motor (fig. 2-37) converts electrical energy from the battery into mechanical or rotating energy to crank the engine. The main difference between an electric starting motor and an electric generator is that in a generator, rotation of the armature in a magnetic field produces voltage. In a motor, current is sent through the AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING 42/ 101
armature and the field; the attraction and repulsion between the magnetic poles of the field and armature coil alternately push and pull the armature around. This rotation (mechanical energy), when properly connected to the flywheel of an engine, causes the engine crankshaft to turn. Starting Motor Construction The construction of the all starting motors is very similar. There are, however, slight design variations. The main parts of a starting motor are as follows: ARMATURE ASSEMBLY- The windings, core, starter shaft, and commutator assembly that spin inside a stationary field. COMMUTATOR END FRAME- The end housing for the brushes, brush springs, and shaft bushings. Figure 2-37.- Typical starting motor. PINION DRIVE ASSEMBLY- The pinion gear, pinion drive mechanism, and solenoid. FIELD FRAME- The center housing that holds the field coils and pole shoes. DRIVE END FRAME- The end housing around the pinion gear, which has a bushing for the armature shaft. ARMATURE ASSEMBLY.- The armature assembly consists of an armature shaft, armature core, commutator, and armature windings. AUTOMOTIVE ELECTRICAL CIRCUITS AND WIRING 43/ 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 and 16: the terminals just enough to secure
Page 17 and 18: Figure 2-6.- Battery leakage test.
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: CAUTION Follow the manufacturer's d
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 and 84: The turn signal flasher unit (fig.
Page 85 and 86: EMERGENCY LIGHT SYSTEM The emergenc
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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