Circuit/System Description
WARNING: This page is about a different car, the 2007 Suzuki XL7. However, it is still accessible from the selected car via links, so may be relevant.
The body control module (BCM) controls the park lamp relay by grounding the control circuit on the park lamp relay when the headlamp switch is turned to the PARK or the HEAD position. This energizes the park lamp relay, illuminating the park lamps.