GM Service Manual Online
For 1990-2009 cars only

If you press the power door lock switch when the key is in the ignition and any door is open, all the doors will lock and then the driver's door will unlock. Be sure to remove the key from the ignition when locking your vehicle.

If the remote keyless entry transmitter is used to lock the doors while the key is in the ignition, a chime will sound three times. All doors will then lock.

This feature prevents the driver door from being locked using the power door locks, if the key is left in the ignition and a door is open.

Press the power door lock switch to lock all the doors and then unlock the driver door.

Press and hold the power door lock switch for more than three seconds to override this feature.

If the key is removed from the ignition, or if the manual door lock or the Remote Keyless Entry (RKE) transmitter is used, the key could still be locked inside the vehicle. Always remember to take the key with you.