Generator
The generator features the following major components:
| • | The delta stator |
| • | The rectifier bridge |
| • | The rotor with slip rings and brushes |
| • | A conventional pulley |
| • | The regulator |
The pulley and the fan cool the slip ring and the frame.
The generator features permanently lubricated bearings. Service should only include tightening of mount components. Otherwise, replace the generator as a complete unit.
Regulator
The voltage regulator controls the rotor field current in order to limit the system voltage. When the field current is on, the regulator switches the current on and off at a rate of 400 cycles per second in order to perform the following functions:
| • | Radio noise control |
| • | Obtain the correct average current needed for proper system voltage control |
At high speeds, the on-time may be 10 percent with the off-time at 90 percent. At low speeds, the on-time may be 90 percent and the off-time 10 percent.
Circuit Description
The generator provides voltage to operate the vehicle's electrical system and to charge its battery. A magnetic field is created when current flows through the rotor. This field rotates as the rotor is driven by the engine, creating an AC voltage in the stator windings. The AC voltage is converted to DC by the rectifier bridge and is supplied to the electrical system at the battery terminal.
When the engine is running, the generator turn-on signal is sent to the generator from the PCM, turning on the regulator. The generator's voltage regulator controls current to the rotor, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine is started, the regulator senses generator rotation by detecting AC voltage at the stator through an internal wire. Once the engine is running, the regulator varies the field current by controlling the pulse width. This regulates the generator output voltage for proper battery charging and electrical system operation.
The generator turn on signal circuit is connected internally to the voltage regulator and externally to the PCM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the PCM that a problem exists
The PCM monitors the generator turn-on signal circuit and field duty cycle signal circuit for any failures. The system voltage sense circuit receives battery positive voltage that is Hot At All Times through the GEN BATT fuse in the underhood fuse block. This voltage is used by the regulator as the reference for system voltage control.
Charging System Indicator
The body control module (BCM) sends a message to the IPC via the serial peripheral interface (SPI) requesting illumination. The IPC illuminates the charging system indicator when the following occurs:
| • | The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The BCM receives a class 2 message from the PCM requesting illumination. The also BCM sends a class 2 message to the radio in order to activate an audible warning. |
| • | The IPC performs the displays test at the start of each ignition cycle as commanded by the BCM. The indicator illuminates for approximately 3 seconds. |
| • | The PCM determines that the ignition is on, with the engine off or the ignition is in the accessory position. The BCM receives a class 2 message from the PCM requesting illumination. |
