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Summary
  • Tail lights and brake lights are part of one assembly, and many vehicles use the same bulb for both. However, they don’t serve the same purpose.
  • Tail lights illuminate as soon as the headlights are on. Meanwhile, the brake lights are only activated whenever the driver steps on the brake pedal.
  • A burnt bulb, circuit problems, blown-out fuse, and a faulty brake light switch are some of the reasons why rear lights can fail.

Tail lights and brake lights are located at the rear end of the vehicle. Both are usually covered by a single external housing一but does that mean they’re technically the same? Let’s find out. 

What Is a Tail Light?

The term tail light typically refers to the entire tail light assembly, which includes both the tail light that lights up with the headlights and the brake lights . These two lights might seem identical, but they serve different purposes.

What’s the Difference Between Tail Lights and Brake Lights?

You might be wondering which bulb is the brake light and which is the tail light. Distinguishing the motor vehicle tail and brake lights is usually easy and can be done by turning on the headlights. The main difference between tail lights and brake lights is that the former lights up as soon as the headlights are turned on, while the latter only engages upon stepping on the brake pedal. While both lights are red, brake lights tend to emit a more luminous red light. This is because the brake lights are meant to clearly signify that the vehicle is braking even while the tail lights are turned on, while the tail lights are only supposed to make the vehicle’s rear visible at night or in low visibility scenarios. 

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So, are tail lights the same as brake lights? Yes and no. They are part of the same tail light assembly, but they are two different lights that serve different purposes. 

If either the tail light or brake light is faulty, the entire assembly is typically replaced. You simply can’t replace one or the other. 

Close up of car tail light
One filament inside the bulb is for the tail light and the other filament is for the brake light.

Are My Tail Lights and Brake Lights Using the Same Bulb? 

On many vehicles, the tail lights and brake lights share the same bulb. One filament inside the bulb is for the tail light and the other filament is for the brake light. There are also some vehicles that have a separate bulb for each circuit.

You can determine whether your brake lights and tail lights share the same bulb by having an assistant press the brake pedal and noting which bulb illuminates within the tail light assembly.

As an aside, on most vehicles, the brake lights (stop lights) double as turn signals. Typically, the stop lamps are wired through the turn signal switch and its flasher or module so that when the stop lights are activated and a turn signal is selected, the stop light on that side of the car will flash. Exceptions would be vehicles with stand-alone turn signals, which are usually orange rather than red and only serve as turn signals or hazard flashers.

The tail lights, on the other hand, may share the same bulb but aren’t as bright as the turn signal/brake lights, which are brighter and pull more current.

How to Check Your Rear Lights

Your vehicle’s tail lights and brake lights are essential safety components not only for you but for other drivers as well. These lights allow your vehicle to be seen during low-visibility conditions and alert other drivers that you’re slowing down, so it’s important to ensure they’re working properly before driving.

, Tail Lights vs. Brake Lights: Are These Two the Same?

Pro Tip: On many vehicles, the tail light circuit also feeds the instrument lamps, so that if the tail lamp fuse is blown, the instrument lamps are also inoperative. On vehicles wired this way, the instrument lamps will have a separate fuse between the tail light circuit and the instrument panel lamps.

To check if your rear lights are working, turn on the headlights. The tail lights should glow red once they’re on. Next, have someone stand behind your vehicle to check the brake lights. They should shine brighter than the tail lights once you step on the brake pedal.

What Causes Rear Lights to Fail?

There are several reasons that may cause a tail light or brake light to fail. These include:

Burnt Bulb

A burnt bulb is one of the most common reasons for tail lights and brake lights to fail. If you notice your tail lights aren’t working but the brake lights are (and vice versa), it may be time for a bulb replacement. 

Circuit Problems 

Circuit problems, such as damaged wiring and corroded bulb sockets, can result in inoperative rear lighting.

If you have wired a lot of other lights (trailer lamps, aftermarket running board or clearance lamps, etc.) to your tail lamp wiring circuit, the part of the headlight switch that feeds the tail lamps can fail due to overheating. The OEM tail light wiring can also fail and melt its way into other wires. This happens more than you think. Aftermarket wiring should include a relay to carry the extra load.

Blown-Out Fuse

If a fuse blows out, power is cut off from the lights, preventing them from turning on.

car brake light switch
If your brake lights stay on after you’ve stopped stepping on the brake pedal, you may be dealing with a bad brake light switch.

Faulty Brake Light Switch 

If your brake lights stay on after you’ve stopped stepping on the brake pedal (or they don’t come on at all with the pedal depressed), you may be dealing with a bad brake light switch. In some cases, the switch contacts may stick t, causing the switch to continuously supply power to the brake lights even when you’re not stepping on the brake pedal.

See also  How-To Video: Headlight Replacement on 1995 Ford F-250 4x4

The brake light switch may also slip out of position, create a space between its plunger and the pedal, and prevent the switch from being turned off.

Where to Buy New Rear Lights for Your Vehicle

 If your rear lights are dim, faulty, or not working, don’t put off replacing them. Not only do they increase the risk of accidents, but they can also get you in trouble with the law. Luckily, you can get some new lights that are compatible with your vehicle easily at CarParts.com.

Search for the parts you need on our website using your mobile phone or computer, then input your ride’s details into our vehicle selector to view the rear lights that fit your ride. We have a wide selection of high-quality rear lights and tail lights available at competitive prices to help you get more bang for your buck.

Order a rear light today, and we’ll deliver your product straight to your doorstep in as fast as two business days. If you have questions, give us a call using our toll-free hotline to get in touch with our round-the-clock customer service team.

Spare yourself some time and trouble by getting your hands on some new lights as soon as possible. Come check out our collection by visiting our website at CarParts.com.

Get Your Tail Lights Installed. Get $100 Cash Back.
About The Authors
Written By Automotive and Tech Writers

The CarParts.com Research Team is composed of experienced automotive and tech writers working with (ASE)-certified automobile technicians and automotive journalists to bring up-to-date, helpful information to car owners in the US. Guided by CarParts.com's thorough editorial process, our team strives to produce guides and resources DIYers and casual car owners can trust.

Reviewed By Technical Reviewer at CarParts.com

Richard McCuistian has worked for nearly 50 years in the automotive field as a professional technician, an instructor, and a freelance automotive writer for Motor Age, ACtion magazine, Power Stroke Registry, and others. Richard is ASE certified for more than 30 years in 10 categories, including L1 Advanced Engine Performance and Light Vehicle Diesel.

Any information provided on this Website is for informational purposes only and is not intended to replace consultation with a professional mechanic. The accuracy and timeliness of the information may change from the time of publication.

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