If the brake light does not come on, first check the fuse in the mounting block.
If the fuse is OK, check the brake light bulbs. Replace if necessary. If the bulbs are OK, check the brake light switch. The brake light switch is located at the pedal support. When you press the brake pedal, the pin extends. The switch contact closes and the brake light comes on.
Check the brake light switch. To do this, disconnect the two plugs of the brake light switch.
Turn on the ignition.
Connect the two plugs of the brake light switch with a jumper. If the signal now lights up, then the fault is in the switch.
Replace brake light switch.