Generator
The Valeo SG10 and SG12 generators are electrically similar to earlier models. The generators feature the following major components:
| • | The delta stator |
| • | The rectifier bridge |
| • | The rotor with slip rings and brushes |
| • | A conventional pulley |
| • | Dual internal fans |
| • | The regulator |
The pulley and the fan cool the slip ring and the frame.
The generators feature 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 powertrain control module (PCM)/engine control module (ECM), 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/ECM. When the voltage regulator detects a charging system problem, it grounds this circuit to signal the PCM/ECM that a problem exists. The PCM/ECM monitors the generator field duty cycle signal circuit. The system voltage sense circuit receives B+ voltage at the body control module (BCM). This voltage is used by the regulator as the reference for system voltage control.
When the ignition switch is turned to RUN, the charge indicator turns ON for a few seconds (bulb check), then turns OFF. The PCM/ECM commands the charge indicator on by sending a class 2 serial data line message to the instrument panel cluster (IPC) when the PCM/ECM detects a charging system problem.
Charge Indicator
The instrument panel cluster (IPC) illuminates the battery indicator in the message center when the following occurs:
| • | The powertrain control module (PCM)/engine control module (ECM) 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/ECM requesting illumination. |
| • | 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. |
The IPC sends a class 2 message to the radio for audible warning when this indicator is ON.
Regulated Voltage Control (RVC)
The LY7 engine comes equipped with GEN II RVC. Regulated voltage control (RVC) is used to more accurately control the amount of voltage put into the battery based upon the battery state of charge (SOC) and battery temperature.
The main components of the RVC system is a new voltage regulator, the body control module (BCM ), and the engine control module (ECM).
| • | Voltage regulator--Uses a pulse width modulation (PWM) signal on the generator L-terminal circuit instead of a 5-volt reference signal from the ECM to determine voltage output of the generator. |
| • | ECM--Controls the PWM signal to the regulator and provides diagnostics for the generator L-terminal and generator F-terminal. It also provides feedback of the generator F-terminal to the BCM for its calculations. |
| • | BCM--Calculates an estimate of the battery SOC and battery temperature based upon, battery voltage and internal calibrations. When the BCM has determined what voltage the battery should receive, a message is sent to the ECM. This message tells the ECM what percentage to set the PWM signal at. |
With RVC in Closed Loop control of the generator, it can vary the voltage at the battery from 13.4 volts, battery temperature above 70°C (158°F) and battery SOC 95 percent or higher, to 14.9 volts, battery temperature below -30°C (-22°F) and battery SOC 65 percent or lower. If RVC looses control of the generator because of a failure the voltage regulator will default to 13.9 volts at the battery and function as a normal generator.
Circuit Description (LY7)
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 engine control module (ECM) sends a pulse width modulated (PWM) signal to the voltage regulator. The generator's voltage regulator then controls the current to the rotor according to the PWM signal received, thereby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. The PWM signal may vary between 12 percent and 88 percent. The lower the PWM signal percentage the lower the generator voltage output will be. Below 12 percent and above 88 percent the voltage regulator defaults to 13.9 volts. This generator is self starting and does not require voltage on the L-terminal circuit to initiate battery charging. This also means that the generator cannot be commanded OFF with the scan tool. When the voltage regulator detects a charging system problem, it grounds the generator L-terminal circuit to signal the ECM that a problem exists. The ECM also monitors the generator field duty cycle signal circuit for failures.
