Headlamp power

The headlamp switch is a direct input to the BCM. The BCM sends a PCI Bus message to the IPM informing it of a headlamp switch status change. The IPM then turns on power to the headlamps through four "fuseless" circuits. These circuits are electronically controlled and continuously monitored for malfunctions. Power is supplied to each filament in a separate circuit. For vehicles equipped with Daytime Running Lamps (DRL), the IPM electronically steps down the headlamp voltage to provide the desired illumination.