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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’s the Difference Between Tail Lights and Brake Lights?

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.

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

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.

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.   

How to Check Your Rear Lights

man checking his rear light before traveling
To check if your rear lights are working, turn on the headlights.

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. 

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

mechanic holds old rear light bulb
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.

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. 

Blown-Out Fuse

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

Faulty Brake Light Switch 

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.

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. 

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.

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