I actually have read both the quick reference manual and the user manual cover to cover. In many respects, the manual is very incomplete, and/or unclear, about many things.
It typically occurs when I am loading or unloading something bulky and/or heavy in the back, such as grocery bags. While balancing the load in one arm and hand, I clumsily unlock the car and open the back lift with the key with the other, and quickly have to put both the key and the load down, inside the car. (Yes, I could drop the key to the ground instead - but in some cases, that would get the key dirty or immersed in rainwater.)
Sometimes I temporarily just don’t have enough hands to handle the load without putting the keys down.
That there are auto-locking features are clearly indicated in the user manual:
From page 38 of the user manual: “Do not leave the electronic key on top of the instrument panel or near the door pockets when exiting the vehicle. Depending on the radio wave reception conditions, it may be detected by the antenna outside the cabin and the door will become lockable from the outside, possibly trapping the electronic key inside the vehicle.”
From page 39: “The doors may unlock or lock if a large amount of water splashes on the door handle, such as in the rain or in a car wash when the electronic key
is within the effective range. (The doors will automatically be locked after
approximately 60 seconds if the doors are not opened and closed.)”
As near as I can figure, it isn’t water, per se that locks it - it is touching the door handle, possibly on the outside, or some particular spot on it. So - in preparation for opening the door, I touch that handle, and that accidentally activate an auto lock feature.
It is a powered liftgate - it closes itself using a motor, not because the springs are weak. However, I just noticed something on p 39 of the user manual - there is a switch to disable the power back door. It is a bit unclear whether this will do what I want, but I will try this. Part of the problem is that I have not figured out exactly when it activates itself.
Honestly, I haven’t yet truly locked myself out. But I have experimented with the window open, so I can unlock it if it locks itself, and there are a number of conditions where does lock itself. I haven’t even completely figured out what those conditions are. But the only reason I haven’t done so, is because I carry an extra key. As an example, sometimes I accidentally leave the key in the ignition switch, and close the door. So I try to open the door, and touching the handle locks it. Without the spare key I carry, that would be a major problem. On a properly designed car, I wouldn’t need a spare key.
There are many customizations possible regarding locking and unlocking described in the user manual. It doesn’t look from the descriptions that any of them will fix this - though the descriptions are in some cases unclear.
There is one auto-lock function I actually like - it locks itself when the car is taken out of park. But it would be far better if there were no fancy options, if to get this one good feature, I have to risk locking myself out accidentally.
Toyota likes to build a lot of fancy features into their recent vehicles. For the most part, they are more trouble than they are worth. E.g., at some sun visor conditions, a light is turned on - and it stays on after the vehicle is turned off and exited, potentially draining the battery. Again, I chose to replace the donut spare wheel and tire with a full size same type wheel and tire spare. To fit it in the wheel well, I have to deflate it. (BTW I carry two pumps so I can re-inflate it. Two because I’ve had pumps go bad.) But Toyota wheels (which are $300, though I bought one cheaper used) have built in tire pressure sensors - so that activates the cars low pressure warning flags. I could de-activate it by removing the battery - but to do that I would have to demount the tire! Another “feature” is that a lot of the buttons have the same shape. They expect you to take your eyes off to operate the controls. And the first time I needed gas, I had a lot of trouble finding the control to unlock the gas cap cover, because it didn’t occur to me to look on the floor.
Overall, I think simpler non-automatic self-evident features are better than complex automatic ones. The cars and trucks I’ve had before, were all much easier to figure out.