Brake Light Not Working On One Side

Brake Light Not Working On One Side? Here’s How To Fix It!

Functioning brake lights in your vehicle are crucial as they signal to other drivers that you intend to stop or slow down. If you notice that one of your brake lights is not working correctly, it is necessary to address the issue promptly.

So, what should you do when the brake light not working on one side? First, you should examine the bulb. Replace it immediately if it’s damaged. If the bulb is fine, you should check the bulb socket and inspect the wiring for any signs of damage or corrosion. There are several reasons that cause brake lights not working.

In this article, we will talk about what may be causing the problem and give you some tips to prevent it from happening again. So, let’s get started!

Why The Brake Light Not Working On One Side: Causes And Possible Solutions

Why The Brake Light Not Working On One Side

Here are the causes with some symptoms and potential solutions to help you fix the brake light on one side.

Potential CausesHow To Fix
Damaged BulbReplace the damaged bulb with a new one
Corroded Bulb SocketApply a thin layer of dielectric grease
Broken Brake Light SwitchInstall a new brake light switch.
Damaged WiringTry to repair the damaged portion of the wire.
Poor Electrical GroundUse sandpaper to carefully remove debris and rust from the grounding point.
Malfunctioning Electronic Control Module Or Body Control ModuleGet your automobile checked by a good mechanic.

1. Damaged Bulb

Most cars have a brake light system that contains the brake light switch, socket, bulb, and wiring. The brake light switch seals the circuit when you hit the brake pedal. 

However, if one of your brake lights gets damaged, the circuit for that side will be incomplete. Thus, the electricity can’t pass through the burnt-out bulb, and it will not turn on.

Car Damaged Bulb


One of the brake lights won’t light up when you apply the brakes, but the other one will light up. 


If one of your bulbs is burned out, you have to replace it with a new one. The cost of a typical replacement bulb is around $10.

  1. To change the broken bulb, locate the access panel at the rear of the taillight assembly. 
  2. Remove the cover and take out the old bulb by gently turning it in an anticlockwise direction. 
  3. After that, insert the new bulb and fasten it in place by turning it clockwise. 

2. Corroded Bulb Socket

The bulb socket helps complete the electrical link to light the bulb. If the metal contacts on the socket become corroded, it can be difficult for electricity to flow. 

Car Corroded Bulb Socket


You might notice that your brake light on one side will flicker, work improperly, or totally stop working.


  1. To check your socket, look for any corrosion or melted plastic. You can use a Q-tip to remove any grease from the socket. 
  2. Then, clean the socket with sandpaper, a wire brush, or an electrical solvent. 

Most modern cars use dielectric grease to prevent corrosion, so you should apply a thin layer after cleaning.

3. Broken Brake Light Switch

Whenever you press the brake pedal, the brake light switch gets activated and flows electricity to light up the brake lights. However, if the switch is broken, it won’t activate the brake lights on one side of the car. 

Car Broken Brake Light Switch


The light on one side of your car turns on but not on the other. Additionally, you may face difficulty in changing gears.

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Follow these processes to solve the problem. 

  1. Look near the top of the brake pedal arm to access the faulty brake light switch. 
  2. Disconnect the electrical connector from the brake light switch. Simply squeeze the connector or press a release tab to take it off.
  3. You should carefully detach the old switch from its mounting point.
  4. Now, take the new brake light switch and put it in the correct spot on the mount. 
  5. Take the electrical connector and plug it into the new switch. Make sure to connect it firmly until you hear a click.
  6. Once you are done, check if the brake lights are working.

4. Damaged Wiring

If the wiring has any damages, such as cuts, frays, unsecured connections, or rust, it can prevent electricity from flowing to the brake light on that side. 

Car Damaged Wiring


The brake light stops working, appears dimmer than usual or flickers constantly.


To address a problem with defective wiring in your car, follow the process below.

  1. First, park your vehicle and turn off the engine to address any wiring problems.
  2. Check the wiring harness of the malfunctioning brake light properly. You can also use a multimeter to identify where the wire has incurred damage.
  3. Look for detectable signs such as fraying, cuts, or exposed wires.
  4. If you find any faulty wires, you can fix them by using wire cutters to remove the damaged part.
  5. Peel off the end of the wire to uncover fresh copper, then twist and solder the wires together.
  6. Then, cover the repaired portion with heat shrink tubing and seal it tightly using a heat gun.
  7. Afterward, you can use electrical tape to protect the repaired wiring from further harm.
  8. Now, reconnect the electrical connectors and reassemble the brake light housing.
  9. Then, turn on your car’s engine and press the brake pedal to check if the brake light turns on.

5. Poor Electrical Ground

Every time you step on your car’s brake pedal, the brake light switch sends a signal to the brake lights. The ground connection completes the circuit by providing a return path to the electrical current. If the ground connection gets loose or corroded, it builds resistance in the circuit. 

Car Poor Electrical Ground


  • Dim brake light on one side of the vehicle
  • Flickering
  • Brake light is not working 


If you are experiencing poor electrical ground issues in your car, you should check the connections for any greenish-white corrosion or looseness. If you find any, use sandpaper or a wire brush to carefully remove debris and rust from the grounding point.

6. Malfunctioning Electronic Control Module Or Body Control Module

Electronic modules like the ECM or BCM control the brake light operation in modern vehicles. If you experience any issues with your brake lights, it might indicate a problem with these modules. 

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  • The brake lights might not turn on while you are driving
  • After you press the brake pedal, there is a delay in the response of the brake light
  • Warning light flashes on your dashboard
  • The brake light on one side of your vehicle does not illuminate


It is best to take your car to a good mechanic in such cases. The mechanic can help you to get the problem diagnosed and repaired effectively.

For more information on this topic, you can watch this YouTube video.

Tips For Preventing Brake Light From Malfunctioning On One Side Of Your Automobile

If one brake light on your car is malfunctioning, you must take care of it quickly to maintain your driving safety. We have provided you some tips below to avoid brake light malfunctions on one side of your car.

  • Inspect your brake lights regularly
  • Keep your brake lights clean so dirt and grime don’t accumulate on the lenses. You can clean them using a soft cloth and glass cleaner.
  • Over time, brake light bulbs may burn out. You should inspect these bulbs regularly for any signs of discoloration or damage. 
  • During downpours, water can slip into the brake light connections. So, you must check the wiring and brake lights for any signs of water damage.
  • Try to invest in high-quality bulbs
  • When you are replacing the bulbs, make sure you don’t touch them with your bare hands
  • If one of your brake light bulbs gets damaged, you should replace both bulbs on the same side. This will help to ensure that both the bulbs stay in good condition.
Tips For Preventing Brake Light From Malfunctioning On One Side Of Your Automobile
Dealing with brake lights can sometimes be perplexing. While some might find their brake light not working but the tail light still functional, others may face different challenges. It’s essential to understand the intricacies to diagnose the problem efficiently. Furthermore, vehicle-specific issues, like when the Chevy Equinox has its ABS warning light illuminated, can point towards unique problems and solutions. Always ensure to consult with experts or delve into in-depth resources to address these concerns.


For more information on why the brake light is not working on one side, check out the FAQs we have given below.

Q: Can I still drive if my brake light is not working on one side?

You should avoid driving with a broken brake light as it poses a safety hazard to you and other drivers on the road.

Q: How do I know if my brake light is not working on one side? 

You can ask someone to observe the lights when you hit the brakes or park your vehicle in front of a wall and apply pressure to the brakes to see if the light turns on.

Q: Can I use LED bulbs to replace my brake lights? 

Yes, you can use LED bulbs to replace your brake lights. However, you should choose the correct type of bulb for your vehicle, as LED bulbs are available in different sizes and shapes.

Final Words

In conclusion, if your brake light not working on one side, there are a few reasons why it might be happening. You might have a broken bulb, damaged bulb socket, blown fuse, or faulty wiring that you need to check and fix.

By troubleshooting the problem, you can avoid any possible accidents that could occur while you are driving. Remember, it is crucial to regularly inspect and maintain your vehicle’s lighting system to ensure that it is safe and reliable.

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