Audio Unit/Muting

This device controls what audio source is output to the designated speakers. OnStar has the highest priority, and when in use, mutes (blocks) all other audio outputs. This is followed by HFL, then Navigation, and finally the audio output.

HFL, and OnStar both have a dedicated mute line running to the audio unit (The navigation system uses the GA-Net bus to send it's mute signal to the audio unit). If for some reason, the mute signal from any of these devices is on, the audio output from devices of lower priority will not be heard.