Your Turn Signal & Brake Light Broken? Surpising Ways To Fix It

Your vehicle comes with a wide range of lighting parts that let other road users know your intentions. Two of the most important signaling features are the brake and turn signal lights. 

Unfortunately, these lights may fail or start acting erratically at one point or another.

In some cases, you’ll notice the turn signal and brake light not working on one side; this could be the passenger or opposite side. 

If this happens, the vehicle likely uses a single-bulb system where the turn signals and brake lights share the same bulb.

So if the bulb on one side fails, both the turn signal and brake lights will stop functioning as well. However, it’s always good to do some checks and get additional information before drawing any conclusions. 

Why Is My Left Turn Signal and Brake Not Working?

Some vehicles are designed in such a way that the rear turn signal and brake lights use one bulb with two filaments. This mechanism is known as a single-bulb system. 

The filament is the part of the lighting fixture that generates light whenever an electric current flows through it.

In such vehicles, it’s common for the turn signal and brake light to malfunction on the left or right side depending on the bulb that has failed. 

However, it’s crucial to note that this is not the case for all vehicles.

Most cars have turn signals and brake lights operating independently of each other. So when you notice the left signal and brake light not working, you’ll have to identify the underlying issues separately. 

On that note, the most common reason why one of the brake lights or signals might stop working is a burned-out bulb. Other likely causes include a blown fuse, bad ground connection, and wiring issues.

These points are discussed in more detail below:

Is the Brake Light and Turn Signal the Same Bulb?

Unfortunately, there’s no straightforward answer to this question as it comes down to the make/ model of the vehicle. 

As mentioned earlier, some older vehicles use a single bulb system with two filaments. This means that the brake or tail lights and the turn signal functions are housed in one bulb. However, there’s one filament for each of the lights. 

That said, it’s crucial to note that the two serve very different functions.

The brake lights light up whenever the brakes are engaged. This signals to other drivers and road users that you plan to make a stop. In contrast, turn signals let you notify other drivers that you’re changing direction

Identification of the Issue

If you suspect either the turn signals or brake lights to have a problem, you’ll want to verify this as soon as possible. Of particular importance is confirming whether the issue is isolated to the passenger side or the other side. 

The easiest way to do this is to ask a friend or family member to stand behind the vehicle. Next, press down on the brake pedal using your foot. If both brake lights are working, then they should illuminate instantly.

So if one of the brake lights doesn’t light up, then you’ll know there’s an issue.

The direction lights are much easier to troubleshoot than the brake lights. Simply drive around your neighborhood, taking a left or right turn whenever possible.

If the signals are working, they should illuminate each time you shift the respective turn signal lever; be it the left or right turn signal. 

Possible Causes 

Here’s a list of things that can cause the rear light and direction signals to fail:

Burned-out Bulbs

If one of the rear lights or turn signals isn’t working, the most likely issue is a burned-out bulb. These parts are like any other lighting fixtures, which means they have a finite lifespan. 

Generally, turn signals are expected to last for about 4,000 hours while braking lights last for up to 40,000 miles.

That said, these bulbs can burn out faster if you encounter a lot of stop-and-go traffic, which is usually the case when driving in big cities. 

Still, if it’s been a long time since you had your signals or rear lights replaced, then this might be the solution you need. 

Faulty Fuse

Nearly every lighting fixture in vehicles uses a fuse. The purpose of a fuse is to break the current when an excess amount is flowing through it. In doing so, it protects the braking lights or turn signals from severe damage. 

A faulty fuse – be it for the turn signals or brake lights – can disrupt the electrical brake circuit or power supply connected to the lights; hence, causing them to malfunction.

The good news is that a blown fuse can be easily replaced. 

Simply check the vehicle’s manual and identify the location of the fuse box. Typically, this is found in the engine bay or underneath the dashboard. 

Next, remove the blown fuse and replace it with a new one. While you’re at it, ensure the new fuse has the same voltage rating as the initial one. Otherwise, you’ll encounter a similar problem within a short time. 

Wiring Issues

If the bulbs and fuses are in perfect condition, the other likely culprit is wiring. As such, you’ll want to examine the wiring system connected to the braking lights and turn signals. 

Start by checking the wires for visible damage. More specifically, look for frayed, corroded, or broken wires. 

If the wires look fine, then the issue might be more deep-rooted. In this case, you’ll need a multimeter to measure the flow of current along the wiring.

If you come across any open circuit- which means the circuit is incomplete – you’ll need to fix or replace the entire wiring system. 

Troubleshooting Steps – Step-By-Step Guide to Troubleshoot and Fix the Issue

In summary, diagnosing malfunctioning turn signals and brake lights involves these three steps:

Start with bulb replacement 

Since this is the most probable cause, replacing the blown-out bulb should resolve your lighting issue. Here’s how to do it:

  1. Put on the right protective gear, including safety goggles and gloves. 
  2. Remove the tail light by unscrewing the bolts holding it in place
  3. Gently detach the bulb from the socket and replace it with a new one. You should be wearing gloves at this point to avoid leaving residue that can shorten the bulb’s lifespan. 

Check the fuse box for a blown fuse

If neither of the bulbs is burned out, inspect the fuses. Replace any blown fuse with an identical one of similar voltage. 

Examine the wiring for any visible damage 

Finally, check the wiring that powers the signals and braking lights. In modern cars, this wiring harness is positioned behind the panels in the trunk so you’ll have to remove them to gain access. 

Once you do, inspect the wires for damage.

If they’re broken or corroded, replace them with new ones. You should also check whether all the wires are connected properly. Reattach any loose connections you encounter.  


Anytime you notice your turn signal and brake light not working, you might feel slightly scared given the vital functions they play. However, you need not worry too much as these issues can be easily fixed. 

First, identify the underlying problem. This could range from a burned-out bulb to a blown fuse or poor wiring.

Once you’ve figured out the problem, you can repair or replace it accordingly. However, if none of these DIY solutions work, be sure to consult a professional mechanic.

They have much more expertise and knowledge in this area. 


Dean Alvarez, TireForge Head Author

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