The generator provides the voltage to operate the vehicle's electrical system and to charge the battery through CKT 1 (RED). When the ignition switch is placed in RUN, voltage is supplied to the generator terminal L by the powertrain control module (PCM), turning on the regulator. The generator's voltage regulator controls current to the rotor, therby controlling the output voltage. The rotor current is proportional to the electrical pulse width supplied by the regulator. When the engine starts, the regulator senses generator rotation by detecting AC voltage at the stator through an internal circuit. Once the engine is running, the regulator varies the field current by controlling the pulse width. This technique 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 PCM. The PCM monitors the field voltage on the generator F terminal.

The PCM turns on the charge indicator via Class 2 serial data line CKTs 1807 (PPL) whenever undervoltage, overvoltage, or a stopped generator is detected on CKT 225 (RED).