Cadillac 2003 CTS Owner's Manual page 193

Trans (Transmission) Hot
This message indicates that the transmission fluid in
your vehicle is too hot. Stop the vehicle and allow it to
idle until the transmission cools down or until this
message is removed.
Trunk Open
When this message appears on the display, it means that
the trunk lid of your vehicle was not closed completely.
You should make sure that the trunk lid is closed
completely.
--
Idle Engine
This symbol appears
--
with the Trans Hot Idle
Engine message.
This symbol appears with
the Trunk Open message.
Turn Signal On
If you drive your vehicle for more than approximately
1 mile (1.6 km) with a turn signal on, this message
will appear as a reminder to turn off the turn signal.
A multiple chime will sound when this message is
displayed.
This symbol appears
with the Turn Signal
On message.
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