Circuit/System Description
WARNING: This page is about a different car, the 2006 Buick Lucerne. However, it is still accessible from the selected car via links, so may be relevant.
Battery voltage is applied at all times to the left front cornering lamp PCB relay which is part of the underhood fuse block. When the turn signal switch is placed in the left turn position, ground is applied through the left turn signal switch signal circuit to the body control module (BCM) The BCM then applies a ground to the left cornering lamp relay control circuit energizing the relay. With the relay energized, battery voltage is applied through the switch side of the relay, the LF CRN LAMP Fuse and the left front cornering lamp supply voltage circuit to the left front cornering lamp.