The High Beam Control System (HBC) operates to switch the headlights automatically between high and low beams after the ignition is switched ON and the headlight switch is in the AUTO and high beam position.
The High Beam Control System (HBC) determines that it is dark based on the brightness of the surrounding area. At the same time, the High Beam Control System (HBC) indicator light (green) in the instrument cluster illuminates.

NOTE
When the vehicle speed is less than about 20 km/h (12 mph), the High Beam Control System (HBC) switches the headlights to low beams.
High Beam Control System (HBC) (Some models)
Manual SwitchingMazda 6 Owners Manual: Lights-On Reminder
The lights-on reminder is operable when the time setting*1 of the auto headlight
off function is off.
If lights are on and the ignition is switched to ACC or off, a continuous beep
sound will be heard when the driver's door is opened.
*1 If the light switch is left on, the auto headlight off f ...
Mazda 6 Owners Manual: How to Arm the System
1. Close the windows and the moonroof securely (some models).
2. Switch the ignition OFF.
3. Make sure the hood, the doors, and the trunk lid are closed.
4.Press the lock button on the transmitter or lock the driver's door from the
outside with the auxiliary key.
The hazard warning light ...