Garmin GTN 650 Cockpit Reference Guide - Page 41

Message COM RADIOCOM radio needs service. COM RADIOCOM radio may be inoperative. COM RADIOCOM overtemp or undervoltage. Reducing transmitter power. COM RADIOCOM locked to 121.5 MHz. Hold remote COM transfer key to exit. Description The COM radio is reporting that it needs service. The COM radio may continue to function. The COM radio is not communicating properly with the system. COM radio is in overtemp or undervoltage mode and transmitting power has been reduced to prevent damage to the COM radio. Radio range will be reduced. COM radio is locked to 121.5 MHz. Action Contact dealer for service. Press and hold the volume knob or the external COM remote transfer (COM RMT XFR) switch, if installed - this will force the COM radio to 121.5 MHz. Contact dealer for service. Decrease length of COM transmissions, decrease cabin temperature and increase cabin airflow (especially near the GTN). Check aircraft voltage and reduce electrical load as necessary. Contact dealer for service if this message persists. The external COM remote transfer (COM RMT XFR) switch has been held and the COM radio is tuned to 121.5. To exit this mode, hold the COM remote transfer (COM RMT XFR) switch for two seconds. Messages 190-01004-04 Rev. C GTN 625/635/650 Cockpit Reference Guide (CRG) 35