Engine Electrical and Electronic Systems

Engine Electrical System

The tractor engine electrical system is a negative ground system. The charging circuit operates when the engine is running. The alternator in the charging circuit produces direct current for the electrical system.

Starting Motor

12 Volt Starting Motor
(1) Terminal for connection of the ground cable (2) Terminal 30 for connection of the battery cable (3) Terminal 50 for connection of the ignition switch

24 Volt Starting Motor
(1) Terminal for connection of the ground (2) Terminal 30 for connection of the battery cable (3) Terminal 50 for connection of ignition switch

The starting motor turns the engine via a gear on the engine flywheel. The starting motor speed must be high enough in order to initiate a sustained operation of the fuel ignition in the cylinders. The starting motor has a solenoid. When the ignition switch is activated, voltage from the electrical system will cause the solenoid to move the pinion toward the flywheel ring gear of the engine. The electrical contacts in the solenoid close the circuit between the battery and the starting motor just before the pinion engages the ring gear. This causes the starting motor to rotate. This type of activation is called a positive shift. When the engine begins to run, the overrunning clutch of the pinion drive prevents damage to the armature. Damage to the armature is caused by excessive speeds. The clutch prevents damage by stopping the mechanical connection. However, the pinion will stay meshed with the ring gear until the ignition switch is released. A spring in the overrunning clutch returns the clutch to the rest position.


The electrical outputs of the alternator have the following characteristics:
• Three-phase
• Full-wave
• Rectified
The engine alternator is an electro-mechanical component. The alternator is driven by a belt from the crankshaft pulley. The alternator charges the storage battery during the engine operation. The alternator is cooled by an external fan which is mounted behind the pulley. The fan may be mounted internally. The fan forces air through the holes in the front of the alternator. The air exits through the holes in the back of the alternator. The tractor alternator converts the mechanical energy and the magnetic field into alternating current and voltage. This conversion is done by rotating a direct current electromagnetic field on the inside of a three-phase stator. The electromagnetic field is generated by electrical current flowing through a rotor. The stator generates alternating current and voltage. The alternating current is changed to direct current by a three-phase, full-wave rectifier. Direct current flows to the output terminal of the alternator. The direct current is used for the charging process.
A regulator is installed on the rear end of the alternator. Two brushes conduct current through two slip rings. The current then flows to the rotor field. A capacitor protects the rectifier from high voltages. The alternator is connected to the battery through the ignition switch. Therefore, tractor alternator excitation occurs when the switch is in the ON position.

Engine Electronic Control System

The Electronic Control Module (ECM) and the sensors are located on the left side of the engine.

A typical example of an electronic control system
(1) Coolant Temperature Sensor (2) Inlet Manifold Temperature Sensor (3) Inlet Manifold Pressure Sensor (4) Fuel Pressure Sensor (5) Electronic Control Module (ECM) (6) Oil Pressure Sensor (7) Primary Speed/Timing Sensor (8) Secondary Speed/Timing Sensor (9) Solenoid for the Fuel Injection Pump

If equipped, the wastegate solenoid is installed on the right side of the engine.

Connector Function

P1 - Machine Harness to Electronic Control Module Connector (64 Pin Connector)
P2 - Engine Harness to ECM Connector (64 Pin Connector)
P500 - Fuel Rail Pump Solenoid Connector (2 Pin Connector)
P402 - Secondary Speed/Timing Sensor (2 Pin Connector)
P401 - Primary Speed/Timing Sensor (2 Pin Connector)
P201 - Engine Oil Pressure Sensor (3 Pin Connector)
P204 - Fuel Rail Pressure Sensor (3 Pin Connector)
P200 - Intake Manifold Pressure Sensor (3 Pin Connector)
P103 - Intake Manifold Temperature Sensor (2 Pin Connector)
P100 - Coolant Temperature Sensor (2 Pin Connector)
J23 - Diagnostic Connector
P681/J681 - Electronic Unit Injectors for No. 1 and No. 2 Cylinders (4 Pin Connector)
P682/J682 - Electronic Unit Injectors for No. 3 and No. 4 Cylinders (4 Pin Connector)
P683/J683 - Electronic Unit Injectors for No. 5 and No. 6 Cylinders (4 Pin Connector)
P601 - Wastegate Valve (if equipped) (2 Pin Connector)

The 6 cylinder diesel engine with electronically controlled was designed for electronic control. The engine has an Electronic Control Module (ECM), a fuel injection pump and electronic unit injectors. All of these items are electronically controlled. There are also a number of engine sensors. Turbocharged engines can be equipped with an electronically controlled waste gate for the turbocharger. The Diesel Engine Electronic Control Module (ECM) controls the engine operating parameters through the software within the ECM and the inputs from the various sensors. The software contains parameters that control the engine operation. The parameters include all of the operating maps and customer selected parameters.

The electronic control system has the following components:
• ECM (Electronic Control Module)
• Pressure sensors
• Temperature Sensors
• Crankshaft position sensor
• Secondary position sensor
• The solenoid for the fuel injection pump
• Wastegate solenoid
• Electronic unit injectors