Generator (G895877)

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The generator is a self exciting type manufactured by Denso and is capable of producing an output current of 90/150 Amps. The generator is located at the front RH side of the engine, and is secured to an engine mounted bracket with a top pivot bolt and 2 lower bolts. The generator mountings provide the electrical ground connection for the generator.

The generator pulley is driven by the engine crankshaft pulley via the accessory drive belt. For additional information, refer to: Accessory Drive (303-05D Accessory Drive - TDV8 3.6L Diesel, Description and Operation).

The generator comprises the following major components:

• Stator
• Rotor
• Rectifier pack
• Regulator.

Stator

The stator contains 3 sets of coils manufactured from copper wire with the ends formed into a 'star' connection. Rotation of the rotor within the stator produces an Alternating Current (AC) in the coils.

Rotor

The rotor comprises a field winding, wound around an iron core and mounted on a common shaft. The ends of the common shaft form the magnetic north and south poles. The rotor is housed within the stator and mounted on bearings to provide smooth running and support, due to the side loading applied by the accessory drive belt tension.

During engine cranking when generator speed is low, the ignition switch supply provides an excitation current to the rotor via brushes and contact slip rings at the end of the common shaft. As the generator speed increases the generator becomes self exciting.

Rectifier

The rectifier converts the AC current produced in the stator coils into Direct Current (DC) that is required by the vehicle electrical system. The rectifier also prevents current flow from the battery to the generator when the generator output voltage is less than the battery voltage.

The rectifier comprises 12 semi-conductor diodes, 6 mounted on the positive heat sink and 6 on the negative. The heat sink dissipates the resultant heat created in the electrical conversion process.

Regulator

The regulator provides a controllable variable voltage output from the generator. A threaded copper post connection on the generator outer casing supplies the rectified and regulated DC current from the generator, via a large diameter cable to the battery positive terminal. A 3-pin electrical connector located on the rear outer casing provides 2 terminals for the hardwired generator monitoring and control connections to the Engine Control Module (ECM), and a single battery sensing connection between the regulator and vehicle battery positive terminal via a 5 amp fuse located in the Central Junction Box (CJB).

An additional diode is located within the regulator and is used to control feedback through the battery voltage signal line.

The ECM contains software maps that provide a mathematical model of battery electrolyte temperature, and constantly receives information from the regulator regarding the actual battery voltage. Based on the information received from the regulator, the ECM communicates a predicted output voltage to the regulator that is required to effectively charge the battery without causing overcharging. The regulator adjusts the supply voltage to the battery to meet the required output voltage determined by the ECM. This control cycle is repeated under a closed-loop condition.

The ECM monitors the generator for mechanical failure or a fault in the connections between the generator and ECM. If a fault is detected a Diagnostic Trouble Code (DTC) is stored in the ECM memory, and if necessary, a message is communicated on the high speed Controller Area Network (CAN) bus to the instrument cluster to illuminate the charge warning indicator lamp. For additional information, refer to: Instrument Cluster (413-01 Instrument Cluster, Description and Operation).

During engine starting, the charge warning indicator lamp is illuminated in the instrument cluster when the ignition is energized, and is extinguished when the engine starts and the ECM detects a generator output voltage.

During engine idling, varying electrical loads will affect the engine idling speed. To maintain the correct engine idling speed, the ECM constantly adjusts engine fueling in proportion to the actual battery voltage information received from the regulator.

The load management system comprises software resident in the Automatic Temperature Control (ATC) module. For additional information, refer to: Control Components (412-04 Control Components, Description and Operation).

The purpose of load management is to protect the battery state-of-charge during abnormal usage of the vehicle. The system will request the Media Orientated System Transport (MOST) ring and the air suspension system to enter 'power save' mode, and will modulate features such as seat and screen heating to prevent the battery voltage becoming critically low to the point where the vehicle becomes un-operational. A 'WARNING - LOW BATTERY' message will be displayed in the message center.

For additional information, refer to: Information and Message Center (413-08 Information and Message Center, Description and Operation).