GM Service Manual Online
For 1990-2009 cars only

With an automatic transmission, the vehicle is pre-programmed to automatically lock the doors when shifted out of P (Park). All doors unlock when the vehicle is shifted back into P (Park).

With a manual transmission, the vehicle is pre-programmed to automatically lock the doors when the vehicle speed reached 15 mph (24 km/h). Removing the key from the ignition unlocks the doors.

To program the automatic door locks, see "Automatic Door Locks" under DIC Operation and Displays.