Circuit/System Description
WARNING: This page is about a different car, the 2017 GMC Canyon and 2017 Chevrolet Colorado. However, it is still accessible from the selected car via links, so may be relevant.
When learning the security code, as well as the challenge and response sequence, the engine control module (ECM) is placed in learn mode. Once the security code and challenge/response are learned, learn mode will be exited when the engine is successfully started.