What is the blinking blue light in the car?

[DeEleanor]

In a car, the blinking blue light is an anti-theft indicator. Here is relevant information: Function of the anti-theft light: Its purpose is to flash when the driver locks the doors using the remote control after exiting the vehicle, indicating that the car's anti-theft system has been activated. The car anti-theft system is designed to prevent theft of the vehicle or items inside it. It consists of an electronically controlled remote or key, electronic control circuits, alarm devices, and actuators. Types of electronic anti-theft systems: Key-controlled, where the system is armed or disarmed by using the key to lock or unlock the doors. Remote-controlled, where the system can remotely lock or unlock the doors, meaning the anti-theft system can be armed or disarmed from a distance.

[DiColton]

Last week, I also encountered this situation in my car, especially noticeable when driving at night. That blinking blue light is most commonly the anti-theft system indicator, which flashes near the dashboard or center console after locking the car, mainly to scare off thieves. Some dash cams also emit a blue light when in standby mode, especially models with parking monitoring features. By the way, if you have a GPS tracker installed, a flashing blue light indicates it's sending signals. The worst-case scenario is an electrical circuit issue, such as poor contact in a module causing abnormal blinking—this requires immediate inspection of the wiring. I remember a friend’s Bluetooth module malfunctioned and flashed similarly, costing over 200 yuan to fix in the end.

[McCassandra]

From the experience of auto repair shops, a flashing blue light is usually an indicator light for electronic devices. It is normal for the anti-theft system's blue light to flash regularly after locking the vehicle; additionally, aftermarket dash cams often emit blue light in night mode. Another possibility is the indicator light in the wireless charging area for phones. The most concerning scenario is irregular flashing, which could indicate a short circuit in the fuse box or water damage to a control module. For example, last month, a car owner had to replace a BCM module at a cost of 800 yuan due to water damage caused by clogged drainage holes during car washing, resulting in erratic blue light flashing.

[Keegan]

The blue light on the lower left side of my steering wheel flashed for three days, and it turned out to be the newly installed tire pressure monitoring transmitter running out of battery. There are generally three most common types of such lights: the factory-installed anti-theft warning light flashes intermittently and slowly; aftermarket radar detectors use a blue light to indicate operational status; and then there are the low-battery warning lights for various small car gadgets. Bluetooth audio adapters and USB car chargers also emit blue flashes when malfunctioning, though usually at a more rapid pace.