Giao thong Newspaper's hotline received a question from a reader about whether one side of the car's brake light is dimmer than the other, or even almost not lit, when the driver steps on the brake pedal. Will this cause the vehicle's registration to fail?

Regarding this issue, a representative of a vehicle inspection center said that brake lights have the task of signaling to other traffic participants that the driver is braking, thereby allowing them to pay attention, proactively adjust speed or change direction of travel to avoid collisions.

According to the National Technical Regulation on technical safety and environmental protection for automobiles, brake lights must be installed in symmetrical pairs on automobiles, located at the rear of the vehicle, in the taillight cluster and must have the same red light color.

According to QCVN 122:2024 regulations on inspection of circulating cars, in case of braking with one side light dark and the other side light bright, two errors are simultaneously committed: When braking, the number of lights operating at the same time of the symmetrical pair of lights is not synchronized in color and size of the light area and the light intensity and light area do not ensure observation and recognition at a distance of 20 m.

These are two errors that fall under the category of critical defects (MaD), so the car will fail the brake light inspection.

This means that the car fails the inspection, the owner must fix it and bring the car for re-inspection, to avoid having to go back to the inspection unit.

The representative of the inspection center also said that currently, many car models have up to 3 brake lights because the manufacturer has designed an additional brake light on the rearview mirror of the car (called the central brake light), in addition to the two symmetrical brake lights according to the regulations of QCVN 122:2024.

However, for vehicles with 3 brake lights, the center light located on the rearview mirror, if not lit, still passes the inspection, because this is considered an auxiliary brake light.

"The most important thing to evaluate the operation of the brake lights is the pair of brake lights mounted symmetrically in the rear light cluster according to QCVN 122:2024," the representative of the inspection center added.