Keyless Entry Control Module
WARNING: This page is about a different car, the 2017 Chevrolet Spark. However, it is still accessible from the selected car via links, so may be relevant.
The keyless entry control module is responsible for activating the low frequency antenna when the ignition mode switch is pressed. The antennas emit a challenge to the keyless entry transmitter. The transmitter receives this challenge and emits it's response as an RF message.