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: Control valve body removal
On-Vehicle Removal
Warning
Using compressed air can cause dirt and other particles to fly
out, causing injury to the eyes. Wear protective eyes whenever using
compressed air.
Caution
Clean the transaxle exterior throughout with a steam cleaner or
cleaning solvents before removal ...
Mazda 6 Owners Manual: Customer Assistance (U.S.A.)
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If you have any questions or recommendations for improvement regarding the service
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