Possessed Door Lock (Faulty door ajar switch)

Short Story:
The car was not actually possessed. It was indeed locking all the doors by itself WITH the keys IN the car. I tried putting new batteries in the key fobs which did not help. It turned out to be a faulty door ajar switch that was not sending the signal to the car that the door was ever opened. This triggered the standard 30 second door lock as if the door was never opened. It was only the rear passenger door with the issue.

I have seen posts of people with the opposite problem that the car thinks the door is not closed when it is closed, but never this way around. I hope this helps someone else. You can lock your keys in your Prius and it sucks.

Long Story:
My 2008 Prius decided to take parenting into it's own hands and lock my fit throwing three year old inside the cabin along with my keys, purse and cell phone last weekend.

After much trauma and what felt like many hours, I was able to talk my son through unlocking and opening the door from the inside. The child safety latch was on his door which I totally forgot about so when he pulled the inner handle, the car anti theft alarm activated and scared the bah-jeezers out of him. I calmed him down through the closed window and then I had him climb into the front seat to try the door. The alarm blaring the whole time. I was able to get him to push the unlock button and pull the interior handle while I pulled on the outside handle. Three tries on the handle and WHAOOO, he was free.

The self locking door issue started a week ago and I thought just the key fob battery needed replacing. I did that and still the issue persisted.

I took my car to my local Toyota dealership and they thought I was nuts or stupid when I explained that the doors keep locking by themselves with my keys inside the car . I can understand them thinking I was stupid or crazy, maybe both.

I offered to replicate the problem for them. The Service Adviser jumped at the offer since seeing is believing sometimes. I locked all the doors. Then went around to the rear passenger side where my son's car seat lives. I unlocked all the doors and opened the rear passenger door, set my keys on the middle console. The door was still open, then 30 seconds and CLUNK! All the doors locked while the rear door was open and the keys IN the car. The service guy was amazed and shocked. The car DID lock by itself. He called out one of the "big wigs" in a nice golf polo shirt. He didn't believe either until I did the demo again. He was very concerned and rightly so after all the other strange Prius issues that have been happening lately. I'm sure they were worried about another potential law suit or something, LOL. Poor guys.

After some more demos and testing we narrowed it down to it happening only on the one door. Then $280 later and also my broken fuel gauge being fixed with a re-set, I was able to get my car.