I'm not mechanic, just trying to help.
from experience I know the brake light bulbs use 2 filaments light bulbs.
Also make sure the filaments are not touching each other. sometimes there could be a bad one causing a chain reaction
does the upper 3rd brake light turn on when you push the brake pedal?
from experience I know the brake light bulbs use 2 filaments light bulbs.

Also make sure the filaments are not touching each other. sometimes there could be a bad one causing a chain reaction
does the upper 3rd brake light turn on when you push the brake pedal?