How to Replace a Third Brake Light (Step by Step)

Where you access the third brake light depends on what you're driving. On a sedan, open the trunk and look up at the rear parcel shelf or the area just below the rear window. There's usually a plastic trim panel with a snap cover or a couple of screws. On a hatchback or SUV, open the lift gate and check the headliner trim at the top of the rear window opening. On a pickup truck, go inside the cab and check the rear of the headliner near the back glass. Remove any screws and pop the trim cover off to expose the back of the housing. Most of these pop off without any tools once the screws are out.

Before you go looking for a bulb, check what kind of housing you have. Look at the back of the unit. If you see a socket you can twist out, you've got a standard replaceable bulb. If the back of the housing shows a strip of LEDs behind a sealed lens with no visible socket, the whole housing needs to be replaced. Most vehicles from the late 1980s through the early 2010s use replaceable bulbs. A lot of vehicles after 2012 or so have sealed LED assemblies. If yours is sealed, skip to the CTA section below and find the right replacement housing for your vehicle.

Grip the socket and twist it counterclockwise about a quarter turn, then pull it straight out of the housing. For small wedge-type bulbs (921, 194, 168), the bulb pulls straight out of the socket with light pressure. For bayonet-style bulbs (1157, 3157), push the bulb in slightly and twist counterclockwise, then pull it out. Once the socket is out, take a close look at the metal contacts inside. Green corrosion or black discoloration from heat means the socket is on its way out. Clean the contacts with fine sandpaper while you're in there. Skipping this step is how new bulbs fail in three months.

Push the new bulb into the socket. Wedge-type bulbs press straight in until they're firm and flush. Bayonet-style bulbs go in with a push and clockwise twist. If you're handling a halogen bulb, use gloves or hold the bulb by the plastic base. Fingerprint oils on halogen glass create hot spots that burn the bulb out prematurely. If you're installing an LED replacement and it doesn't light up when you test, pull it out and rotate it 180 degrees. Most LED bulbs are polarity-sensitive and will only work in one orientation.

Don't button things up until you've confirmed the new bulb actually works. Plug the socket back into the housing, then have someone press the brake pedal while you look from outside. If you're working alone, set something heavy on the brake pedal or use a brick. The center brake light should come on bright and solid. If nothing happens, check that the bulb is fully seated in the socket, then check that the socket is fully locked into the housing. If it still won't light, the issue might be the socket, a blown fuse, or broken wiring in the hatch flex cable.

Once the bulb is confirmed working, twist the socket clockwise back into the housing to lock it. Snap the plastic trim cover back into place, making sure all the clips seat fully. Reinstall any screws you removed. On hatchbacks and SUVs, press firmly around the edges of the trim panel to make sure every clip is engaged before you close the lift gate. A trim panel that's only half-seated will rattle on every bump.