1. Disconnect the wire from the terminal «minus» battery.
2. Disconnect the pads with wires from the switch terminals.
3. Loosen the switch locknut and unscrew the switch from its bracket.
4. Check the brake light switch. For a serviceable brake light switch with a fully protruding stem, the tester readings should tend to zero, i.e. contact is closed.
5. When the stem is sunk by 4–5 mm, the tester readings should tend to infinity, i.e. contact is open.
6. Install the switch in reverse order. Adjust the position of the switch so that the brake lights come on even with low brake pedal travel.