Circuit Description
WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. 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 of 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.