GM Service Manual Online
For 1990-2009 cars only

If your vehicle has power door locks and the remote keyless entry system, it has an automatic lock/unlock feature.

If your vehicle has an automatic transmission, it is programmed from the factory to lock all doors automatically when the shift lever is moved out of PARK (P). All the doors will unlock when the shift lever is moved back into PARK (P).

If your vehicle has a manual transmission, it is programmed from the factory to lock all the doors when the vehicle speed is greater than 15 mph (24 km/h). The doors will unlock when the key is removed from the ignition.

To change the automatic door lock and unlock settings, see "Automatic Door Locks" under DIC Controls and Displays .