Spontaneous door unlock, triangle warning light

A weird thing happened to me just now in my 2005 Prius -- several times, while driving, the doors spontaneously came unlocked, while the red triangle with the exclamation point flashed on the dashboard. I was able each time to relock the doors from the master switch, and nothing else seemed to happen. At first, I thought I might be accidentally hitting a button on the key in my pocket, but I couldn't reproduce the effect by intentionally hitting the buttons. I stopped at my destination (Home Depot) and hoped the problem would go away as suddenly as it appeared, but it happened again on the way back.

I have SKS. The key is a relatively new one that I had made some time after I got the car in 2010 (so 2011, maybe?). Any ideas?

 

I took it into the dealer this morning. They want to replace the shifter, and possibly the battery (they said they can't test it properly until the shifter's replaced). ~$1000 total.

The symptoms actually had changed for the worse -- now, it put up a notice saying something like "Caution: Put the car in Park. The batteries won't charge in Neutral." Meanwhile it's in Drive the whole time, still actually driving fine mind you. But the red triangle and warning beep were continuous. Then, when the dealer tried the car, the error didn't happen, until an hour or so in (they did the steering column recall first).

 

More of the story...

They called me the next day to say they'd replaced the shifter (~$750), and "good news", the battery was OK, and didn't need replacing. (They included the printout from the battery tester in the papers they gave me, and it rated the battery health as "very good".) So, I went to pick it up, and... immediately, it was doing the same thing. I go in and tell them, the mechanic happens to be there, and we go back to the car together. Everything works perfectly. At this point, he suspects the door latch sensor... but we try and try to get the problem to surface, with no effect, except (the mechanic says -- I didn't see it) one brief flash of the "door open" light. So, I leave the car with them overnight for more testing.

The next day... they couldn't reproduce it, so they're giving up. I decide to leave it for the night, and pick it up this morning. I get there, and immediately, it's doing the same thing. So, this being Carmax Laurel Toyota, I head to the sales desk and get them to appraise it. The appraiser, of course, finds nothing wrong. As I head home, there are only a few brief moments of weirdness on the return trip, mostly at the start, but also a couple times turning corners.

I'm beginning to wonder if part of the issue is my weight. I'm a heavy guy, probably heavier than anyone Carmax had driving it. And, when I had the mechanic as a passenger, that weighed down the other side of the car, so it was more balanced. Am I totally off base with this idea?

BTW, although I knew it wasn't the problem, I can't honestly say that there was nothing wrong with the shifter -- it had been a little sticky ever since I got the car, not enough to be an issue, but just enough to notice. It works better now. So, I can't say that the repair had no value, even though it didn't solve my problem.

 

I wish I knew a place. Back when I got the car, I didn't know of any local shops that I could trust with a Prius. But seeing how many Prii are around now (three others just on my block!), there must be some demand for independent service. I haven't needed much, but I've been generally pleased with Carmax Laurel Toyota, but they aren't cheap.

 

Not in the time I've had it (five years). Before that, I think so, but I don't know any details, except that a side mirror was replaced IIRC.

 

Nope.

 

They said that nothing showed up. :shrug:

 

$5000. Within what KBB.com tells me to expect, albeit towards the low side.

It kills me to think of leaving this car, but I guess that's where I'm at right now. I feel like I was just getting to know it, after five years. But it's probably entering the age of more frequent breakdowns...

I did already half-heartedly try recording it with my iPad, but couldn't make that work.

 

Farewell, old friend. You were a great car for five years, but then you went crazy. You're CarMax's problem now.