Cadillac 2010 DTS - Manual (Page 119)

To assist in finding the lock, the vehicle has the
following:
To use the lock:
1. Insert the key into the security lock slot and turn it
so the slot is in the horizontal position.
2. Close the door.
3. Do the same for the other rear door.
To open a rear door when the security lock is on, do the
following:
1. Unlock the door using the Remote Keyless
Entry (RKE) transmitter, if the vehicle has one, the
power door lock switch, or by lifting the rear door
manual lock.
2. Open the door from the outside.
To cancel the rear door security lock:
1. Unlock the door and open it from the outside.
2. Insert the key into the security lock slot and turn it
so the slot is in the vertical position.
3. Do the same for the other rear door.
Lockout Protection
If the key is in the ignition and the power door lock
switch is used to lock the doors, all doors will lock
and then the driver door will unlock. It is always
recommended that the ignition key is removed from
the vehicle when locking the doors.
The lockout protection feature can be overridden by
holding the power door lock switch for three seconds or
longer.
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