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HOMESERVICE MANUALSCHEVROLET2008HHR LT, 2.4 P, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 106 (BATTERY, CHARGING SYSTEM AND STARTING SYSTEM)DESCRIPTION AND OPERATIONCHARGING SYSTEM DESCRIPTION AND OPERATIONCHARGING SYSTEM OPERATIONNOTES
2008 Chevrolet HHR LT, 2.4 P, Automatic

Charging System Operation: Notes

2008 Chevrolet HHR LT, 2.4 P, AutomaticSECTION Notes
WARNING: This page is about a different car, the 2009 Chevrolet HHR. However, it is still accessible from the selected car via links, so may be relevant.

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 engine control module (ECM) controls the generator through the generator L-terminal control circuit. The signal is a 5-volt pulse width modulation (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 ECM. This information is sent to the body control module (BCM). The signal is a 12-volt 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.

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Stop DIY work and contact a certified mechanic immediately if any of the following apply:

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