Circuit/System Description
WARNING: This page is about a different car, the 2009 Cadillac STS. However, it is still accessible from the selected car via links, so may be relevant.
The vehicle navigation radio and Onstar® system (If equipped) both utilize the cellular microphone located on the inside rearview mirror to receive voice commands. The navigation radio receives an audio voice signal from the communication interface module (CIM). If the vehicle is not equipped with Onstar®, the microphone is connected only to the navigation radio.