Central Door Unlocking System; Power Door Locks - Buick 2005 Park Avenue Owner's Manual

There are several ways to lock and unlock your vehicle.
To lock or unlock the driver's door from the outside,
use your door key or remote keyless entry transmitter.
To lock or unlock the doors from the inside, move the
manual lock on the door handle forward or rearward.
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Central Door Unlocking System

If your vehicle has a theft-deterrent system, all doors
will unlock if the key is held in the outside key cylinder
unlock position for more than two seconds. The
doors will also unlock if the key is turned to the unlock
position twice in three seconds.

Power Door Locks

With power door locks, you
can lock or unlock all
doors on your vehicle
using either the driver's or
the front passenger's
power door lock switch.