Brake lights and tail lights are two different items.
Do you see the bulbout idiot light work when first starting the car?
It is still likely to be a bad sensor that has gone OPEN and needs
soldering.

Do you have a multimeter? Check for plus 12 volts at fuse 4
that supplies power to the brake switch (Green yellow wire)

Then brake and tail lights get their plus 12V via the bulb out sensor.
(It is not a relay) (Blue/Red wire from brake switch to sensor pin 54/9)

Output from sensor to left brake light: Yellow/Red wire Pin 54L/10
right : Yellow wire Pin 54R/11

Use the meter to find out if and where you lose Plus 12V
If other lights (tail lights) are working then your ground should be OK.