GMC Cadillac CTS 2004 Owner's Manual page 200

When this message appears, the personalization
features previously stored are turned off. If you want
your customized settings to be automatically recalled
when you use the remote keyless entry transmitter
or when you remove the key from the ignition, you
must enable them in the DIC. See DIC Vehicle
Personalization on page 3-88 for more information.
This message is also used to identify the driver
(1, 2 or 3) on the Navigation system.
Right Rear Door Ajar
When this message appears on the display, the right
rear door it means that the passenger's side rear
door was not closed completely. You should check to
make sure that the door is closed completely.
3-80
This symbol appears
with the Right Rear Door
Ajar message.
Service AC (Air Conditioning) System
This message appears when the electronic sensors that
control the air conditioning and heating systems are
no longer working. Have the climate control system
serviced by your GM dealer if you notice a drop
in heating and air conditioning efficiency.
This symbol appears
with the Service AC
System message.