Circuit/System Description
WARNING: This page is about a different car, the 2022 Cadillac CT4. However, it is still accessible from the selected car via links, so may be relevant.
The K73 Telematics Control Module provides the B24LF Mobile Telephone Microphone - Left Front or the B24 Mobile Telephone Microphone (depending on radio RPO) with a supplied voltage on the cellular phone microphone high signal circuit 655. When the microphone is in use, voice data from the user is sent back through the K73 Telematics Control Module to the radio on the cellular microphone low reference circuit 654.