0438934 JOHNSON FUEL RESERVOIR

Illustration 1 g00767353
Typical example
Grounding Stud To Battery Ground ("−")
Illustration 2 g00767355
Typical example
Alternate Grounding Stud To Battery Ground ("−")
The engine must have a wire ground to the battery.Ground wires or ground straps should be combined at ground studs that are only for ground use. The engine grounds should be inspected after every 250 hours of machine operation. All of the grounds should be tight and free of corrosion.The engine alternator should be battery ground with a wire size that is capable of managing the full charging current of the alternator.
When boost starting an engine, the instructions in Systems Operation, "Engine Starting" should be followed in order to properly start the engine.This engine may be equipped with a 12 volt starting system or a 24 volt starting system. Only equal voltage for boost starting should be used. The use of a higher voltage will damage the electrical system.The Electronic Control Module (ECM) must be disconnected at the "J1/P1" and "J2/P2" locations before welding on the vehicle.
Engine Electrical System
The electrical system has three separate circuits:
Charging circuit
Starting circuit
Low amperage circuitSome of the electrical system components are used in more than one circuit. The following components are used in each of the three circuits:
Battery
Circuit breaker
Ammeter
Battery cablesThe charging circuit is in operation when the engine is running. An alternator generates electricity for the charging circuit. A voltage regulator in the circuit controls the electrical output in order 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 machine has a disconnect switch, the starting circuit can operate only after the disconnect switch is put in the ON position.The starting circuit is in operation only when the start switch is activated.Both the low amperage circuit and the charging circuit are connected to the same side of the ammeter. The starting circuit is connected to the opposite side of the ammeter.
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.
Charging System Components
Alternator
Illustration 3 g01139928
Alternator components
(1) Brush holder
(2) Rear frame
(3) Rotor
(4) Stator
(5) Drive end frame
(6) Fan assembly
(7) Slip rings
(8) Rectifier The alternator has three-phase, full-wave, rectified output. The alternator uses brushes to generate electricity.The alternator is an electrical component and a mechanical component that is driven by a belt from engine rotation. The alternator is used to charge the storage battery during engine operation. The alternator is cooled by a fan that is a part of the alternator. The fan pulls air through holes in the back of the alternator. The air exits the front of the alternator and the air cools the alternator in the process.The alternator converts mechanical energy and magnetic energy into alternating current (AC) and voltage. This process is done by rotating an electromagnetic field (rotor) that is direct current (DC) inside a three-phase stator. The alternating current and the voltage that is generated by the stator are changed to direct current. This change is accomplished by a system that uses three-phase, full-wave, rectified outputs. The three-phase, full-wave, rectified outputs have been converted by six rectifier diodes that are made of silicon. The alternator also has a diode trio. A diode trio is an assembly that is made up of three exciter diodes. The diode trio rectifies field current that is needed to start the charging process. Direct current flows to the alternator output terminal.A solid-state regulator is installed in the back of the alternator. Two brushes conduct the current through two slip rings to the field coil on the rotor.A capacitor is mounted in the back of the alternator. The capacitor protects the rectifier from high voltages. The capacitor also suppresses radio noise sources.The voltage regulator is a solid-state electronic switch that controls the alternator output. The voltage regulator limits the alternator voltage to a preset value by controlling the field current. The voltage regulator feels the voltage in the system. The voltage regulator switches ON and OFF many times per second in order to control the field current for the alternator. The alternator uses the field current in order to generate the required voltage output.Note: Refer to Service Manual, SENR3862 for detailed service information for the Delco Remy 27 SI Series Alternator.Note: If the alternator is connected to an engine component, the ground strap must connect that engine component to the frame or to the battery ground.Starting System Components
Starting Solenoid
A solenoid is a magnetic switch that does two basic operations:
The solenoid closes the high current starting motor circuit with a low current start switch circuit.
The solenoid engages the starter motor pinion with the ring gear.
Illustration 4 g00285112