Theory Of Operation
WARNING: This page is about a different car, the 2020 Jeep Renegade. However, it is still accessible from the selected car via links, so may be relevant.
When the Body Control Module (BCM) receives an input from the Headlamp Switch, requesting Park Lamp illumination, the BCM provides a voltage output, through the License Plate Lamp Control circuit, to the License Plate Lamps. A ground path for the License Plate Lamps is present through the harness to the body sheet metal.