Generator
The generators feature the following major components:
| • | The rotor with slip rings and brushes |
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:
| • | 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 F terminal 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 field duty cycle signal circuit. The system voltage sense
circuit receives battery positive voltage that is Hot At All Times through
the A/C RLY fuse in the under-hood junction block. This voltage
is used by the regulator as the reference for system voltage control.
Charging System Indicator
The IPC illuminates the charge indicator in the message center when the following occurs:
| • | The PCM detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the PCM requesting illumination. |
| • | The IPC determines that the system voltage is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the body control module (BCM) indicating the system voltage. |
| • | The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds. |
| • | The ignition is ON, with the engine OFF. |
