For 1990-2009 cars

The generator provides DC voltage to operate the vehicle's electrical system and to charge the battery. A magnetic field is created when current flows through the rotor windings. The rotor is belt driven by the engine creating an AC voltage as this field rotates within the stator windings. The AC voltage is converted to DC voltage by the rectifier bridge and is then supplied to the electrical system at the generator battery terminal.

When the engine is running, the generator turn-on signal is sent to the generator from the PCM, turning on the regulator. The generator's voltage regulator controls the current flow to the rotor, thereby controlling the generator output voltage. The rotor current is proportional to an electrical pulse width modulated voltage 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's output voltage for proper battery charging and electrical system operation. The system voltage sense circuit receives B+ voltage that is Hot At All Times. This voltage is used by the regulator as the reference for system voltage control.

The powertrain control module (PCM) controls the CHARGE warning lamp using a solid state lamp driver. The lamp driver turns the lamp ON whenever the lamp driver detects the following conditions:

• | Undervoltage

• | Overvoltage

• | A stopped generator