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: Climate control unit inspection
Full-auto Air Conditioner
1. Connect the all center panel connectors.
2. Turn the ignition switch to ON position.
3. Measure the voltage at each climate control unit terminal and refer to the
terminal voltage list.
If not as specified, inspect the parts listed under Action and the
relate ...
Mazda 6 Owners Manual: Technical data
ENGINE
LUBRICATION SYSTEM
Note
The maintenance intervals on scheduled maintenance table (See
SCHEDULED MAINTENANCE TABLE) can only be supported by the use of following
oils.
Recommended engine oil
COOLING SYSTEM
FUEL AND EMISSION CONTROL SYSTEMS
ENGINE ELECTRICAL SYSTEM
...