The reasons why the taillights are always on are:

1. The brake pad return spring does not return;

2. The liquid level in the brake oil cup drops;

3. The tail light circuit is faulty;

4. The brake light switch is damaged;

5. The handbrake is not released.

Automobile taillights include lamps and light bulbs in the rear of the car. The function of the lamps is to aggregate the light emitted by the bulbs and then emit them, thereby enhancing the brightness and range of the light emitted by the bulbs. Car taillights include turn signals, brake lights, position lights, rear fog lights, reversing lights, and parking lights. The turn signals and brake lights are symmetrical, one on the left and one on the left.