Toyota Sienna front door sensor malfunction causes battery drain on Toyota Sienna

Some Toyota Sienna owners report experiencing battery drain due to a malfunctioning front door sensor, which can lead to continuous signals that deplete the battery. Additionally, they note that understanding the two types of batteries in the vehicle—the Traction or High Voltage battery and the traditional 12V battery—is essential for troubleshooting. Common causes of battery drain include internal battery degradation, a faulty alternator, parasitic draw, and prolonged parking periods. Owners have observed that if the "door open" dashboard light remains illuminated, it may indicate an issue with the door switch located in the latch mechanism. To identify the specific cause of the drain, some owners recommend testing for parasitic draw by measuring amperage and isolating excessive draw through a systematic removal of fuses. Addressing these sensor malfunctions is crucial for preventing further battery drain issues.