GM Service Manual Online
For 1990-2009 cars only

When the power door lock switch is pressed with the key in the ignition, and any door is open, all the doors lock and the driver door unlocks. When doors are closed with the key in the ignition, the horn will sound as a reminder.

If the doors are locked with the Remote Keyless Entry (RKE) transmitter, and the key is in the ignition, a chime sounds and all except the driver door lock.

The lockout protection feature can be overridden by holding the power door lock switch for three seconds.