GM Service Manual Online
For 1990-2009 cars only

When locking the doors with the power lock switch or the keyless entry transmitter and a door or the liftgate (if equipped) is open, the delayed locking feature will delay locking the doors until five seconds after the last door is closed. Three chimes will sound to signal that the delayed locking feature is in use.

Pressing the power lock switch twice will override the delayed locking feature and immediately lock all the doors.

Delayed locking can be programmed using the DIC. See DIC Vehicle Customization .