Brake or tail light is not working: repair options and cost

Updated: March 12, 2020
We need brake lights and tail lights for safe driving. What are the repair options if your car is out of warranty and one of the rear lights is not working? The first question is whether it's a regular bulb or LEDs (light emitting diodes)? See the photo. In most cases, an LED taillight comes as one unit and is replaced as an assembly. Read more about replacing the taillight assembly.
Removing the taillight bulbRemoving the bulb in the 2009 Honda Accord.
If it's just a regular bulb that is out, it's an inexpensive problem. If you are not comfortable changing the bulb yourself, you can take your car to a local dealer or any auto repair shop. Replacing one brake or tail light bulb in an average car will cost $10-$55 labor plus the cost of the bulb ($1-$7). In some cars it's very easy to do; in others the taillight assembly might need to be removed in order to replace a bulb.
If you want to replace the bulb yourself, the key is to use the right bulb type and install it properly to avoid electrical issues.
Removing the taillight bulbRemoving the bulb in the 2009 Honda Accord.
The owner's manual for your car not only lists the bulb types, but for most cars, provides instructions on how to replace one. In many modern cars, the bulb is installed in a socket. For example, in this 2009 Honda Accord, the owner's manual says: Remove the socket by turning it one-quarter turn counterclockwise (see the photo above). Pull the bulb straight out of its socket. Push the new bulb straight into the socket until it bottoms. Insert the socket back into the light assembly. Turn it clockwise to lock it in place.
Bulb typeBulb type. Fig2.
The bulb type is also printed on the bulb itself; see the photo. Most auto parts stores carry the common bulb types. If you want to be sure to install the new bulb the same way, mark the position of the bulb with a marker or snap a photo before removing it. In some cars, bulbs are installed on a board that is attached to the taillight assembly.

How to check if the bulb is good? In most cases, it's easy to see when a bulb is burned out. See this photo of a burned-out and a new license plate bulb.
Checking a light bulb in a carThis bulb is good.
Another way to check it is to measure the resistance of the bulb using a multimeter. A good bulb should have resistance from 0 to 3 Ohms. If the multimeter shows OL, which means the resistance is out of range (no continuity), the bulb is bad. It's also possible to check the bulb using a 12V power source, or, as in this photo, a 9V battery.

Double-filament bulbs are used for two functions; they can work,
Double-filament bulbDouble-filament bulb.
for example, as a brake light and a tail light or as a turn signal light and a tail light. Often, when one filament fails, the other might still work. When testing a double-filament bulb with a multimeter, each filament has to be tested separately.

Can a bad bulb socket cause the light not to work? Yes, whenever you check or change a bulb, or if the new bulb doesn't work, check the socket that holds it.
Good and melted brake light bulb socketThe bulb socket on the left image is melted and must be replaced.
Often the bulb doesn't work because the socket is melted or burned out or has a bad connection; see the photo. In this case, the bulb socket will also need to be replaced. If your local parts store doesn't have it, you can order it from a dealer. A bulb socket costs from $5 to $15. In some cars, the socket comes as part of the taillight wiring harness and may cost from $15 to $35.

How long do bulbs last in a car? In some cars, bulbs can last up to 10-15 years, although in other cars, they are known to fail much earlier. It depends on where the bulb is located, the quality of the bulb and many other factors.

What can cause the third brake light to not work? A working third brake light, which is technically called a center high-mounted stop lamp, helps avoid rear-end collisions.
Third brake light is not working The third brake light or "center high-mounted stop lamp" is not working.
According to the NHTSA, the addition of a mandatory center high-mounted stop lamp in 1986 resulted in a 4-percent reduction in rear-end crashes. If the third brake light doesn't work, it could just be a bad bulb(s) or LED unit. However, because of its location, problems with the third brake light are often caused by other reasons. For example, in many cars and pickup trucks, water can leak inside the third brake light assembly or connector and cause corrosion. In this case, not only will the bulb(s) have to be changed, but the light assembly might need to be re-sealed. If there is a separate seal (gasket) that leaked, it will need to be replaced. The connector must be checked for corrosion too. See how a corroded connector looks.
Trunk lid harness Trunk lid harness.
Replacing a separate LED center high-mounted stop lamp might cost $150-$320 (parts and labor).

If a third brake light or other lights are installed on a trunk lid or a liftgate, another common problem is a broken wire inside the harness that connects to the trunk lid or liftgate. In older vehicles, repeated opening and closing of the trunk lid or liftgate can cause the wires inside the harness to break or short-circuit between each other over time. For example, this issue is common in older German cars. Often, shorted wires in the harness can cause the brake light fuse to blow. If the third brake light is not working, check the bulb(s) and look for signs of corrosion in the connector. If the bulb(s) is okay, the electrical circuit must be checked.

What can cause all taillights or all brake lights to not work? Although it's rare for two or three bulbs to fail at the same time, bulbs must be checked first.
Third brake light is not working One of the ways to check brake lights is to look at the reflection when you park your car near the reflective wall.
If the bulbs are good, it means that the electric circuit for the affected lights is down. For example, a bad brake light switch can cause the brake light circuit (and all three brake lights) to not work. If the electric circuit is down, the first step is to check the fuse.

Most cars have two or three fuse boxes; you can find the fuse location in the owner's manual. One circuit can have more than one fuse. If all the fuses are OK, the circuit must be diagnosed. In modern cars, lights are controlled by electronic control modules. Mechanics at a dealership or well-equipped auto repair shop can check any of the control modules with a scan tool or multimeter.

The fuse for the affected lights is blown. A blown fuse is easy to replace, but if the fuse is blown, it means there is a short circuit. For example, one of the bulbs could be shorted or installed the wrong way. Another common problem is when wires that connect to the trailer harness rub against a metal part and short. Damaged wires inside the trunk lid harness could also short between each other and cause the fuse to blow. It's not always easy to find the reason for a blown fuse, but a knowledgeable mechanic should be able to help. Most dealers and auto repair shops charge a flat fee ($50-$130) for initial diagnostics of an electrical problem like this.