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 ECM/PCM 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 5 volt PWM signal of 128 Hz with a duty cycle of 0-100%. Normal duty cycle is between 5-95%. Between 0-5% and 95-100% 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 %	11.0 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 ECM/PCM, this information is sent to the BCM. The signal is a 5 volt PWM signal of 128 Hz with a duty cycle of 0-100%. Normal duty cycle is between 5-99%. Between 0-5% and 100% are for diagnostic purposes.