GM Service Manual Online
For 1990-2009 cars only

With this feature, the doors will automatically lock when the vehicle is shifted out of PARK (P) for vehicles with an automatic transaxle, or the vehicle speed is greater than 5 mph  (8 km/h) for vehicles with a manual transaxle. The doors will automatically unlock when the ignition is turned off.

To turn the automatic door locking feature on or off, do the following:

  1. Turn the ignition to RUN with the engine off and all of the doors closed.
  2. Press and hold the power door lock button in the lock position until the horn chirps twice.

To turn the automatic door unlocking feature on or off, do the following:

  1. Turn the ignition to RUN with the engine off and all of the doors closed.
  2. Press and hold the power door lock button in the unlock position until the horn chirps twice.