Motorola MOTONAV TN500 Series Installation Manual page 11

When the switches are all down (or "on"), then the
channels are all connected to the MOTONAV device
during a hands-free call. When one of the switches is
moved up (or "off"), the audio from the vehicle
entertainment system will pass-through to the
speaker while in a call.
Note: Do not disable both front speaker channels or
the hands-free audio will not be heard.
install the car kit 9