Brake lights are red lights on the rear of a vehicle that light up when the brake pedal is depressed. Most modern vehicles have three brake lights: one in the rear window and one on each side of the back of the vehicle. The brake light in the rear window is now mandatory for all new vehicles sold in the United States. Brake lights are extremely important safety devices; they warn vehicles of a stop in the flow of traffic. If a brake light goes out, both brake lights should be replaced, because brake lights tend to burn out in pairs.
Disconnect the negative ("-") battery cable. Open the trunk. In the back of the trunk toward the taillights is a plastic trim panel; remove the trim clips center retainer with a small screwdriver, and pull the clip from the plastic trim. There will be four or five clips that will need to be removed. Pull the plastic trim from the vehicle.
Pull the carpet trim back carefully to access the brake light retaining nuts. Using a socket set, remove the three retaining nuts. Pull the taillight away from the body to remove the electric connector from the taillight. Squeeze the back of the electric connector, and pull away from the light bulb socket. Turn the plastic light socket counterclockwise a quarter of a turn to release it from the lens. Pull the brake bulb straight out from the socket.
Check the part number on the side of the new bulb against the old bulb's part number -- they should match. Push the new bulb straight in to the socket. Slide the light socket back into the lens, giving the light socket a quarter turn clockwise to lock the socket into the taillight. Reinstall the electric connection, squeezing the connection until a clicking sound is heard. Reattach the taillight to the body using the three nuts that were previously removed.
Reinstall the plastic trim in the trunk using the trim clips. The outer portion of the clips needs to be inserted into each of the clip holes; the center pin of the clip can then be pushed in to lock the clip. Close the trunk. Reinstall the negative battery cable.
