Voltage to the headlamp switch is available at all times through the following components:

When the headlamp switch is in the AUTO position, a light sensor located in the right speaker grill senses either a daylight or a dark condition. The body control module (BCM) controls the operation of the following components:

The headlamp power relay coil is grounded through the following components:

The RH headlamp high beam bulb receives current through CKT 198 (DK BLU). The body control module (BCM) energizes the following components:

When the headlamp grounding relay is energized, the ground path for regular headlamp operation is eliminated. At the same time, the DRL relay is energized. The DRL relay being energized then places both headlamp high beam bulbs in series. This operation causes both of the headlights to light at half there normal output. The ground circuit for the daytime running lights (DRL) is completed through the following components:

A voltage signal is sent to the body control module (BCM), through CKT 524 (PPL), to confirm proper DRL operation.