[PTG1212]

I have a 2001 Malibu. When you push the door lock twice it immediately locks the car doors. When you push the lock once, it goes on delay to allow you to open back door or whatever. When you close all doors after about 5 sec or so the horn gives a short toot and the headlights will flash, indicating that the doors have locked. That's normal operation.

As far as tooting right after starting the car or putting it in park, you've got me on that one. That doesn't sound normal.