A Connecting Cable Between Units Is Displayed In Yellow.

Area with yellow connection lines	Description	Possible malfunction location / Action to take
Control unit ==> BTHF	When either one of the following items is detected: TEL adapter unit power supply and ground circuits are malfunctioning. AV communication circuits between audio unit and TEL adapter unit are malfunctioning.	TEL adapter unit power supply and ground circuits. AV communication circuits between audio unit and TEL adapter unit.