Charging Circuit: Notes

The generator supplies DC voltage to operate the vehicle's electrical systems and to charge the battery. The output of the generator is controlled by the built-in regulator.

The regulator directly controls the field with a Pulse Width Modulated (PWM) signal, which is measured in duty cycles. When the ignition switch is first turned to RUN, before the engine is started, voltage is applied to the regulator by the BCM. The regulator, which is in a field strobe function, applies a small percentage of the duty cycle to the field windings to produce a magnetic field. As the generator RPM increases, the field strobe function is disabled and normal regulation occurs. The Body Control Module (BCM) monitors the regulator from the field terminal of the generator (BCM parameter DB51). If the duty cycle falls below 7% ON, the BCM will sense a fault and indicate a problem.

AC voltage is generated in three stator windings in the generator. This is changed to DC voltage by the rectifier bridge. This DC output is applied to the battery and the vehicle circuits at the battery terminal of the generator. The battery terminal also supplies voltage to the regulator for field voltage supply. The `S' terminal is used for voltage monitoring.

The regulator will ground terminal L when there is an under-voltage condition, a broken drive belt, an open or shorted field circuit or malfunctioning regulator. The BCM senses a low voltage and then indicates a problem.