Definitely by the switch position on the Gen 4. Not sure about others. I am glad I set my headlights to turn off immediately rather than depend on the default timeout.
OP has a Gen3, like my own Gen3s. I'd think that a failed headlight auto-off incident would look just like a successful case, with the switch left in the same position either way.
If it really was THAT dead for THAT long.....it probably is a gonner. I certainly wouldn't trust it, even if it passes a load test. And......sorry that I missed the subtle indications that you were completely locked out of the vehicle. I hope this incident convinces you to keep TWO electronic and mechanical keys in good working order.
It seems that a significant number of used car buyers are getting only a single key fob. I think we should be reminding future buyers that because the car came from the factory with two keys, they should demand two working fobs as a condition of sale. Or get a good discount to cover the cost of a new fob, with programming.
And an owner's manual too. I always consider that missing essentials like that are a sign that the owner doesn't really take care of his stuff.
Yes, but that still doesn't answer the question of why the 12V died. I'm not taking the 'headlights' answer in Post #17 without some supporting evidence. A locksmith simply noting that the headlight switch was 'on' doesn't cut it for models such as Prius with built-in auto-off.
Two things about that: I believe the auto-off interval can be changed; maybe yours is set too long. Once the battery starts getting weak, a combination of small things might push it over the edge......culminated with the headlights staying on too long.
The longest setpoint in my manual is 2 minutes. If that is enough to push it over the edge today, then it was already going to go over the edge by itself within a few days.
I have accidentally over-ridden the auto shut off feature a couple of times by fiddling with stuff after shutting off the car. I usually keep an eye on the car to make sure they go off or hit the lock button on the FOB. I have been meaning to reset the delay to a much shorter time or even instant off as I really don't need them on to see after parked. I too have noticed in the past that many used car dealers only supply 1 key fob. I suspect they keep an extra in case you get behind on the payments.
It is time for customers to start demanding two working fobs, or a discount to cover a replacement. I also suspect that many of those extra fobs kept by the dealer are ending up on ebay, as an additional profit for the dealer.
I have something similar - took my car in for a collision fender repair. It took a week. Everything working fine. Now the SKS locks won’t work. The remote works to press to unlock and lock the car. But you cannot touch the handle to lock and unlock anymore. Does it need reprogramming or Is the 12 volt dead? All other features work and the car runs fine. The remote batteries have been recently replaced.
For 2012-2015 models, there is an SKS On/Off selection in the vehcle setup menu on the dashboard screen. This does not disable the lock/unlock buttons on the fob, only the automatic proximity detection gets shut off. But being away from my Prius at the moment, I can't give you a precise description. If this setting got flipped, then the car also will not start with the fob in your pocket, it must held up to the Power button. If the car will start with the fob away from the Power button but the SKS doesn't work with the doors, then I'd suspect something incomplete about the repair work.
My assumption (and it's just that) is that previous owners trade the car in with only one FOB thinking that the second is worth some money, or can be re-programmed to their new Toyota. Once they realize that it can't be re-programmed to their new car, and that it's all but worthless unless they have the ability to "virginize" it, then it sits in a drawer in the kitchen for years until somebody pulls it out one day and says, "What's this for? We don't even own a Toyota anymore." But that's just a WAG.