Theory Of Operation

When the Body Control Module (BCM) receives an input signal from the Headlamp Switch, requesting Low Beam Headlamp illumination, the BCM sends 12 volts through the Left and Right Headlamp Relay Control circuits to activate the Left and Right Headlamp Low Beam Relays (integral to the Power Distribution Center (PDC) Assembly). When the Headlamp Low Beam Relays are active, both relays send voltage to the Left and Right Headlamp Assemblies, through the Left and Right Low Beam Driver circuits. A separate ground circuit is used for the Low and High Beam Lamps.