Garmin GNS 430 Pilot's Manual And Reference page 34

SECTION 2
COM
Stuck Microphone
As mentioned previously in this section, when the GNS
430 is transmitting, a 'TX' indication appears in the COM
Window. If the microphone key is stuck or accidentally
left in the on position; or the microphone continues to
transmit after the key is released, the COM transmitter
automatically times out (ceases transmitting) after 35
seconds of continuous broadcasting. A 'COM push-to-
talk key stuck' message (Figure 2-11) is displayed as long
as the condition continues.
Figure 2-11 Message Page
2-6 GNS 430 Pilot's Guide and Reference