I want to get to the bottom of this, if we can. I have bought new brake lights, but have not installed them.
To be sure I am understanding & using terms correctly, on my 2005 Toyota Sienna LE, the rear lights include some mounted on the rear hatch, while others are mounted on the corner of the car's body. Those on the corner include the turn indicator on top, and the tail light on the bottom. By contrast, the brake lights are on the left & right edges of the rear door/hatch, and at the top of the hatch (total of three brake lights).
The brake light which was not working, but now is working, was the driver side brake light. The only thing I did which might have made it start working (besides changing the fuse, which you have ruled out), is to change the rear driver side tail light bulb, whose glass was coming loose from its metal base.
Can you tell me, with the driver side brake light now working, how to identify & fix whatever problem should exist in the wiring or bulb socket?