2004 QX56 Doors Automatically Locking & Unlocking - HELP!

[Socaldiablo]

So my fairly reliable 04' QX56 has a new problem that I just found out about today. For some reason, the truck is unlocking the doors on its own will. I've noticed a few times that when I go to unlock the truck, it's already unlocked. My wife drives this vehicle mostly so I kept blaming her for leaving the doors unlocked after she would leave the vehicle and she kept denying it. This has happened several times in the last several weeks. So she locked the truck this morning after getting back from dropping my son off at school (I know she did b/c I heard the horn sound when she locked it) and when she just left to pick him up, the doors were unlocked again. I've also heard the truck's horn sound on it's own while parked in the last several weeks, as if someone had just locked it with the key fob. Something is clearly wrong here as the truck is locking and unlocking the doors on its own. My assumption is the lock actuator has a short and is tripping itself so a new part will need to be installed. Anyone know if my assumptions are correct and if so, where is this part located in the vehicle? We park the truck on the street in front of our house in Los Angeles, which is in a very urban part of town (mid city LA). If someone realizes the doors are unlocked, the truck could easily be stolen. It's just a matter of time. I need to fix this ASAP!

[Towncivilian]

Make sure all the door switches are working right - the easiest way to check this is to set the dome light to "door" and see if an open door lights up the dome light.

[Socaldiablo]

They are ...the dome lights have always lit up when any of the doors are opened. Everything seems totally normal. This problem has not occured in several weeks now. It is very odd ...it seemed to be doing it quite a bit and then when I harped on my wife about remembering to lock the doors (and she said every time that she was), now the problem has gone away for at least the time being. I'm starting to wonder if she thought she was locking them and wasn't. She always has her hands full with a baby/car seat, purse, etc. so it's probably very easy to forget. I'll chime back in on this if I start to see the problem come back.