Lexus GS430 User Manual page 308

AUDIO
Using your audio system: some basics
This section describes some of the basic features of the Lexus
audio system. Some information may not pertain to your
system.
Your audio system works when the engine switch is selected
in "ACC" or "IG−ON" mode.
NOTICE
To prevent the battery from being discharged, do not
leave the audio system on longer than necessary when
the engine is not running.
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Vehicles with navigation system only:
G21047a
By pushing the button above, you can operate the speech
command system.
For the operation of the speech command system, see the
"Navigation System Owner's Manual".