Circuit/System Description
WARNING: This page is about a different car, the 2020 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
The interior keyless entry antenna 3 is located inside of the rear compartment on the underside of the trunk lid and is used to establish low frequency communications with the keyless entry transmitter. As the ignition switch is pressed the BCM will transmit low frequency signals to this interior keyless entry antenna 3.