What is the purpose of the delayed locking feature on my 07 Silverado? I've absolutly HAD IT with my truck locking me out!!

The first time this happened my truck was new and I hopped out to pump gas, closed my driver door (keys halfway in ignition) and heard my truck lock. Crap. Had my neighbor bring me my spare keys. Note to self, do not leave keys in ignition and close door! Lesson learned...or so I thought.

The next time this happened, I remembered the security locking feature and took my keys out of the ignition, placed them in cup holder, then jumped out to pump gas. It was raining and I closed my driver door. THE DOOR LOCKED! Wth the keys weren't even in the ignition?!?! Again, friend brought my spare. Lesson cemented, engrained, forever carved into my memory. I never, repeat NEVER, close my doors if my keys are inside my truck.

I went for years without issue. Sometimes I hear a chime as I exit my truck and I know that means my doors are going to auto lock at some point. I can't really determine or notice a rhyme or reason for when it happens. I'm not sure what triggers it or why sometimes I hit the lock button and my doors won't lock until after I've closed the door? It really isn't imporatant because I simply learned to NEVER close the door if the keys are inside.

However this past weekend admist running errands I left my keys on the backseat with the rear door open while I changed my sons diaper on the tailgate. In my head I reminded myself not to close the door. As I was changing a poopy diaper, someone was trying to pull into the parking spot next to me so my son's dad reached over and shut my truck door. !#@$% PANIC immediately set in and before I could get any words out I heard the all too familiar fatal CLICK of my doors locking.

Now I keep my manual door unlocker (a bent piece of metal) in the bed of my truck & have scratched up my passenger side door jamb breaking into my truck.

How the hell do I disable this wonderful "auto lock" feature?

I am a big girl, I would love it if the only time my truck locked it was because I was turning a key or pushing my fob.