Circuit/System Description
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The low beam headlamps are controlled by two different inputs to the body control module (BCM), the headlamp switch, or when in the Auto mode, the ambient light sensor. When the BCM receives a low beam headlamps ON command, it grounds the headlamp low beam relay control circuit in order to energize the low beam PCB relay. With the relay energized, battery voltage is applied through switch side of the relay, both LO BEAM fuses, and the low beam supply voltage circuits to the low beam headlamps.