Principles of Operation: Notes

After the engine is started, voltage is supplied through the warning indicator I circuit 904 (LG/RD) from the powertrain control module (PCM) to the voltage regulator. This turns the regulator on, allowing current to flow from the battery sensing A circuit 35 (OG/LB) to the generator field coil. At this time, the generator begins to generate current which is then supplied to the vehicle electrical system through the output (B+) terminal of the generator.

With the system functioning normally, the generator output current is determined by the voltage of the A circuit 35 (OG/LB). The A circuit 35 (OG/LB) voltage is compared to a set voltage internal to the regulator, and the regulator controls the generator field current to maintain the correct generator output.

The set voltage varies with the temperature, and is typically higher in cold temperatures and lower in warm temperatures. This allows for better battery recharge in the winter and reduces the chance of overcharging in the summer.