DTC P0620: Alternator Control Circuit: General Description

The alternator management system controls the charging voltage output to improve fuel economy, manage alternator load under various operating conditions, keep the battery charged, and protect the battery from over-charging. The ECM/PCM controls the output voltage by using a duty cycle (charging control, discharging control, normal control) based on battery conditions and vehicle operating conditions. It is important to have a stable power supply, so a battery sensor is part of the charging system. The battery sensor is mounted on the battery negative terminal. It transmits battery voltage, current, and temperature information to the ECM/PCM. The ECM/PCM controls output voltage by increasing or decreasing the duty cycle on the COM circuit to the alternator based on these signals.