GM Service Manual Online
For 1990-2009 cars only

If the vehicle has an automatic transmission, the vehicle is programmed so that the doors will lock automatically when all doors are closed, the ignition is on, and the shift lever is moved out of P (Park). The doors will automatically unlock when the vehicle is stopped and the shift lever is moved into P (Park).

If the vehicle has a manual transmission, the vehicle is programmed so that the doors will lock automatically after the vehicle speed reaches 5 mph (8 km). The doors will automatically unlock when the ignition is turned off and the key is removed from the ignition.

If someone needs to exit the vehicle once the doors are locked, have that person use the manual lever or power door lock switch. When the door is closed again, it will not lock automatically. Use the manual lever or the power door lock switch to lock the door.

The power door locks can be programmed through prompts displayed on the Driver Information Center (DIC). For more information on programming, see DIC Vehicle Customization .