Blinking blind spot lights: What you need to know on the road

What does a flashing light on the side mirror mean? What does it tell the driver of such a car, and what does it communicate to the person driving in the adjacent lane? It's valuable to know how advanced safety systems in cars work, even if our own vehicles don't have them.

The blind spot detection system is one of the simplest yet most useful electronic systems for enhancing daily safety. When driving next to another car on the highway or approaching a vehicle in the right lane from the left lane, you may notice a flashing orange or red light on the left mirror of that vehicle. It's often located on the side of the mirror. This light signals to the driver that you are approaching and also informs you that they might not be aware of your presence.

This is how the BLIS (Blind Spot Information System) works, aiming to warn the driver about objects in the vehicle's blind spot. This is an area that the driver cannot see in the usual way through mirrors or by turning their head.

This system monitors a larger area because it's designed to alert drivers about vehicles that might soon enter the blind spot. It is believed to cover the area from the middle pillar (B pillar) to several yards behind the car. BLIS does not inform about vehicles directly in the same lane, meaning those approaching from behind.

The purpose of this system is to prevent a collision that might occur if a driver equipped with such a system decides to change lanes. Despite the clarity of the signal, it doesn't guarantee that the driver will refrain from making the maneuver. Therefore, seeing such a light in another car's mirror is also a warning: this driver doesn't see you.

It's important to pay attention to turn signals, which in many cars are placed on mirrors and can be confused with BLIS system lights, especially from behind. In mirrors of cars like the Seat Leon, these lights are exceptionally similar. If a driver turns on the left turn signal while driving next to you, they probably don't see you or are waiting for you to let them pass.