Item number 2

The only time the doors are suppose to automatically lock is: The car is locked, you approach your car and hit the unlock on the key fob, you hit it twice cause you wanted all doors open, now a friend comes up to you and you have a conversation, at about the 2 minute mark the doors will automatically lock because no one has opened a door. That is the only time the doors will automatically lock, and it is designed to do that.

Item number 1

If you open all the locks, and then open a door and close it, and the locks automatically lock you have a problem with the central locking system and it needs to be repaired.
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Rich K. http://www.volvospeed.com/bay13.htm