Charging System Operation: Notes
The purpose of the charging system is to maintain the battery charge and vehicle loads. There are 6 modes of operation and they include:
- Charge Mode
- Fuel Economy Mode
- Voltage Reduction Mode
- Start Up Mode
- Windshield Deice Mode
- Battery Sulfation Mode
The powertrain control module (PCM)/engine control module (ECM) controls the generator through the generator field control circuit. It monitors the generator performance through the generator field duty cycle signal circuit. The signal is a pulse width modulated (PWM) signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 5-95 percent. Between 0-5 percent and 95-100 percent are for diagnostic purposes. The following table shows the commanded duty cycle and output voltage of the generator:
| Commanded Duty Cycle | Generator Output Voltage |
|---|---|
| 10% | 11 V |
| 20% | 11.56 V |
| 30% | 12.12 V |
| 40% | 12.68 V |
| 50% | 13.25 V |
| 60% | 13.81 V |
| 70% | 14.37 V |
| 80% | 14.94 V |
| 90% | 15.5 V |
The generator provides a feedback signal of the generator voltage output through the generator field duty cycle signal circuit to the PCM/ECM, this information is sent to the body control module (BCM). The signal is a PWM signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 5-99 percent. Between 0-5 percent and 100 percent are for diagnostic purposes.