CAP 4B1451 - Caterpillar

Engine Electrical System
Illustration 1 g01339089
(1) Warning lamp (alternator)
(2) Warning lamp (oil pressure)
(3) Warning lamp (coolant temperature)
(4) Fuel shutoff solenoid
(5) Alternator
(6) Engine oil pressure switch
(7) Coolant temperature switch
(8) Glow plugs
(9) Signal for glow plugs
(10) Ignition switch
(11) Electric starting motor
(12) BatteryThe electrical system has two separate circuits.
Charging circuit
Starting circuitSome of the electrical system components are used in more than one circuit. The following items are common in each of the circuits:
Battery
Circuit breaker
Cables
Wires for the batteryThe charging circuit is in operation when the engine is running. An alternator converts mechanical energy to electrical energy for the charging circuit. A voltage regulator in the circuit controls the electrical output to keep the battery at full charge.
The disconnect switch, if equipped, must be in the ON position in order to let the electrical system function. There will be damage to some of the charging circuit components if the engine is running with the disconnect switch in the OFF position.
If the engine has a disconnect switch, the starting circuit can operate only after the disconnect switch is put in the "ON" position.The starting switch is in operation only when the start switch is activated.The charging circuit is connected through the ammeter. The starting circuit is not connected through the ammeter.Automatic Shutdown System
Wiring Diagram for a 15 Amp Alternator
Illustration 2 g01339109
(1) Warning lamp (alternator)
(2) Regulator
(3) Alternator
(4) Battery
(5) Electric starting motor
(6) Warning lamp (oil pressure)
(7) Engine oil pressure switch
(8) Warning lamp (coolant temperature)
(9) Coolant temperature switch
(10) Fuse
(11) Ignition switch
(12) Signal for glow plugs
(13) Glow plugs
(14) Fuel shutoff solenoid
(15) Automatic shutdown device
(16) Electrical connector
(17) Delay fuseElectrical Connector
Illustration 3 g00841411
Connector for the automatic shutdown device (typical example)
(1) Ignition switch (red wire)
(2) Ignition switch (orange wire)
(3) Fuel shutoff solenoid (red and black wire)
(4) Engine oil pressure switch (brown wire)
(5) Coolant temperature switch (blue wire)
(6) Ground (black wire)Automatic Shutdown Conditions
The engine will shut down if the following conditions continue for more than 10 seconds while you start the engine or for 2 seconds while you operate the engine:Coolant temperature exceeds the following values:All engines ... 110° 3°C (230° 5°F)Engine oil pressure falls below the following values:Engine oil pressure switch that is on the valve mechanism cover ... 29 kPa (4.27 psi)Engine oil pressure switch that is on the cylinder block ... 98 kPa (14.22 psi)Note: There is no automatic shutdown for low coolant level.Note: The capacity of the diode must be 3 A with a reverse voltage of 600 V.Note: The rated current draw of the engine oil pressure switch is 0.42 A (5 W maximum bulb).Note: If necessary, a delay fuse should be used for replacement.Charging System Components
Never operate the alternator without the battery in the circuit. Making or breaking an alternator connection with heavy load on the circuit can cause damage to the regulator.
Alternator
Illustration 4 g00292313
Alternator
(1) Regulator
(2) Roller bearing
(3) Stator winding
(4) Ball bearing
(5) Rectifier bridge
(6) Field winding
(7) Rotor assembly
(8) FanThe alternator is driven by the crankshaft pulley through a belt. When the engine is running, the pulley rotates the shaft inside the alternator. The rotor assembly is attached to the