The brake light switch is located on a flange or bracket protruding from the brake pedal support. With the brake pedal fully released, the plunger of the switch should be fully pressed in, and when the pedal is depressed, the plunger releases, sending electrical current to the brake lights at the rear of the car. To check the brake light switch, observe whether the brake lights illuminate when the pedal is depressed and turn off when released; if they do not, adjust the switch by loosening the locknut and threading the switch inward until its body contacts the brake pedal, then release the pedal. If the lights still do not activate, the switch may not be receiving voltage, could be defective, or there may be an issue with the circuit between the switch and the lights, although it is unlikely that all brake light bulbs are burned out. A voltmeter or test light can be used to verify voltage at one side of the switch connector; if no voltage is present, troubleshoot the circuit from the switch to the fuse box. If voltage is present, check for voltage on the other terminal when the brake pedal is depressed; if absent, replace the switch, and if present, troubleshoot the circuit from the switch to the brake lights. To replace a faulty switch, unplug the electrical connectors and pull the switch out of its bracket, with installation being the reverse of removal, ensuring to adjust the switch as previously described.