Circuit Operation - Charging System

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 ignition switch is placed in RUN, voltage is supplied to generator terminal S through the Battery Thermistor. The Thermistor is mounted on the positive battery cable and senses battery electrolyte temperature. It provides this information to the voltage regulator which uses digital techniques to supply 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 Powertrain Control Module (PCM). The PCM monitors the field voltage on the generator F terminal.