Before starting work: Disconnect the wire from the "–" terminal of the battery.
The brake light switch is mounted on the pedal assembly bracket.
1. Unscrew the plastic nut of the switch, holding the switch mounting nut from turning with a second key.
2. Loosen the lock nut, unscrew the nut securing the switch to the bracket and...
3.... remove the switch from the bracket. Disconnect the wire ends from the switch. Checking the brake light switch is the same as checking the parking brake indicator light switch (see subsection 8.7.1.).
4. Install the switch in the reverse order of removal. Adjust the brake pedal free play (it should be 3-5 mm). Adjustment is made by moving the switch on the bracket. Tighten the lock nut of the switch, holding the nut.
[The source is on the website vazbook.ru]