Cadillac 2006 CTS Owner's Manual page 206

Lights Flash at Lock
This feature allows the exterior lamps to flash once
when the Remote Keyless Entry (RKE) transmitter is
used to lock the vehicle. All doors must be closed
for this feature to work, and the lamps will not flash if
the parking lamps or headlamps are on.
Programmable Modes
Mode 1: ON
Mode 2: OFF
Before your vehicle was shipped from the factory, it was
programmed to Mode 1. The mode to which the
vehicle was programmed may have been changed since
it left the factory.
To program the vehicle to a different mode, use the
following procedure:
1. Enter the personalization portion of the SETUP
menu following the instructions listed previously.
2. Turn the TUNE/SEL knob until LIGHTS FLASH AT
LOCK is highlighted.
3. Press the TUNE/SEL knob to switch back and forth
between on and off.
When the mode is turned on, a check mark will
appear next to the feature name.
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You can select this feature by itself, or you can combine
it with Horn Sounds At Lock so that both the lights
flash and the horn chirps when you lock your vehicle.
The mode you selected is now set. You can either
exit the programming mode by following the instructions
later in this section or program the next feature
available on your vehicle.
Horn Sounds at Lock
This feature sounds the horn once when the Remote
Keyless Entry (RKE) transmitter is used to lock the
vehicle. All doors must be closed for this feature to work.
Programmable Modes
Mode 1: ON
Mode 2: OFF
Before your vehicle was shipped from the factory, it was
programmed to Mode 2. The mode to which the
vehicle was programmed may have been changed since
it left the factory.