Connection check

"Audio": Displays "Exist" when the audio head unit is connected, and "None" when not connected.
"CD-P": Displays "Exist" when the CD player is connected, and "None" when not connected.
"CD-C": Displays "Exist" when the CD changer is connected, and "None" when not connected.
"MD-P": Displays "Exist" when the MD player is connected, and "None" not connected.
"MD-C": Displays "Exist" when the MD changer is connected, and "None" when not connected.
"C cassette": Displays "Exist" when the C cassette unit is connected, and "None" when not connected.
"CD-C1": Displays "Exist" when the in-dash CD changer is connected, and "None" when not connected.
"SAT(SIRIUS)": Displays "Exist" when the satellite radio tuner (SIRIUS) is connected, and "None" when not connected.
"VES": Displays "Exist" when the Video Entertainment System is connected, and "None" not connected.