In my experience in a Subaru, a Toyota, and a Volvo, it seems to be connected to the car's light sensor (so it triggers at the same time as the automatic headli

In my experience in a Subaru, a Toyota, and a Volvo, it seems to be connected to the car's light sensor (so it triggers at the same time as the automatic headlights). A third-party head unit I've tried was just always light.