Skip to content
Brake lights are a vital safety feature on every vehicle, alerting drivers behind you when you're slowing down or stopping.
Without them, your risk of being rear-ended increases dramatically. According to the latest data from the National Highway
Traffic Safety Administration (NHTSA), around 30% of rear-end collisions are linked to faulty or non-functioning brake lights.
Have you ever wondered how many accidents could be prevented by simply ensuring your brake lights are in working order?
If your brake light isn't functioning, you're not just risking a traffic ticket—you're putting yourself and others in danger.
This article is here to help you avoid that. We'll show you how to diagnose and fix brake light problems on your own, saving you a trip to the auto repair shop.
What Causes Brake Lights Not to Work
The brake light circuit is protected by a fuse, and if this fuse blows, the circuit is interrupted, rendering the brake lights non-functional.
Brake light bulbs have a limited lifespan, and if the filament inside the bulb burns out, the light will no longer illuminate.
The brake light switch, which is located near the brake pedal, is responsible for triggering the brake lights when you press the pedal.
If this switch fails, the lights won’t turn on, leading to a potentially dangerous situation. Wiring issues can also play a significant role in brake light failure.
Damaged or frayed wires in the brake light circuit can prevent the lights from receiving the necessary power to operate.
Corroded or loose connections at the light sockets can lead to poor electrical contact, causing intermittent or complete brake light failure.
It depends! The entire tail light assembly may need to be replaced if it has sustained damage or if internal components have failed.
Problem Checklist
❌ Blown Fuse
❌ Burned-Out Bulbs
❌ Faulty Brake Light Switch
❌ Wiring Issues
❌ Corroded or Loose Connections
❌ Faulty Tail Light Assembly
Related Reading: Can the Ancel VD500 OBD II Diagnostic Scanner Reset Brakes?
How to Diagnose a Brake Light Problem
Diagnosing a brake light issue requires a systematic approach to identify the root cause.
Use the ANCEL X7 OBD2 Scanner
Conducting a comprehensive vehicle check. Begin by connecting the X7 to the OBD2 port located beneath the dashboard.
Once connected, follow the on-screen instructions to perform a scan, focusing on the brake light system.
The scanner will identify any issues related to the brake lights, providing diagnostic codes and detailed information to help you address the problem efficiently.
Check the Brake Light Bulbs
Start by inspecting the bulbs.
Remove the lens cover and check if the filament inside the bulb is intact or burned out.
If the bulb is blackened or the filament is broken, it needs to be replaced.
Even if the bulb appears fine, it’s still a good idea to test it with a multimeter or swap it with a known working bulb to be sure.
Inspect the Fuse
Locate the fuse box, which is typically found under the dashboard or in the engine compartment.
Use the vehicle’s manual to identify the fuse related to the brake lights.
Remove the fuse and inspect it. If the metal strip inside is broken, the fuse is blown and needs to be replaced with one of the same rating.
Test the Brake Light Switch
The brake light switch can be tested using a multimeter. First, locate the switch near the brake pedal.
With the multimeter set to measure continuity, press the brake pedal.
The multimeter should show a reading indicating continuity when the pedal is pressed. If not, the switch is faulty and should be replaced.
Examine the Wiring
Check the wiring leading to the brake lights for any visible damage, such as cuts, fraying, or corrosion.
Use a multimeter to check for continuity in the wires. If there’s no continuity, there’s likely a break in the wire that needs to be repaired.
Check the Ground Connection
A poor ground connection can prevent the brake lights from working.
Locate the ground wire and ensure it is securely connected to a clean, rust-free metal surface.
Use a multimeter to test for continuity between the ground wire and the vehicle’s frame. If there’s no continuity, clean the connection or replace the wire.
How Do You Fix a Brake Light Failure
Once you've diagnosed the problem, fixing it can be straightforward or may require some mechanical skill, depending on the issue.
If the bulb is burned out, it should be replaced with a new one of the same type.
Ensure the bulb is seated correctly in the socket, and the lens cover is securely fastened.
If the fuse is blown, it should be replaced with a fuse of the same amperage.
It is important never to use a fuse with a higher rating, as this could lead to electrical damage.
If the brake light switch is faulty, it will need to be replaced.
This typically involves removing a few screws and disconnecting the wiring harness from the old switch before installing the new one.
Damaged wires can be repaired using electrical tape or by splicing in new wire sections.
If the damage is extensive, it may be necessary to replace the entire length of the wire.
Corroded connections can be cleaned with a wire brush or replaced if necessary. Ensure that all connections are tight and secure to prevent future issues.
In cases where the entire tail light assembly is faulty, it will need to be replaced. This involves removing the old assembly, disconnecting the wiring, and installing a new assembly.
Why Is My Brake Light Not Working But the Bulb Is Good
Sometimes, the brake light may not work even though the bulb is in good condition.
A faulty brake light switch is one possible reason for this issue. The switch may not be sending the signal to illuminate the lights.
Wiring problems can also cause brake lights to malfunction,
even if the bulb is good. The wires connecting the brake lights may be broken, frayed, or disconnected, preventing the lights from receiving power.
A blown fuse can also be the culprit.
Even if the bulbs are in good condition, a blown fuse can prevent the brake lights from functioning. It is essential to ensure that the fuse is in working order.
A poor ground connection can cause the brake lights to malfunction.
The ground wire should be checked to ensure it is properly connected to the vehicle’s frame.
Additionally, the socket where the bulb sits could be damaged or corroded, leading to poor contact and preventing the bulb from lighting up.
Conclusion
Ensuring your brake lights are functioning correctly is vital for your safety and that of others on the road.
By understanding the common causes of brake light failure and following the steps to diagnose and fix the issue, you can maintain the reliability of your vehicle's lighting system.
Regular maintenance and prompt attention to any issues can help prevent brake light failures and ensure that your vehicle remains safe and compliant with traffic regulations.
FAQs
Why do my brake lights stay on even when I'm not pressing the pedal?
This could be due to a faulty brake light switch or a problem with the brake pedal itself. The switch might be stuck or misaligned, causing the lights to remain on.
Can I use LED bulbs in my brake lights?
Yes, you can replace standard brake light bulbs with LED bulbs. However, make sure they are compatible with your vehicle and check if any modifications are needed to avoid hyper-flashing or other issues.
What should I do if only one of my brake lights is out?
If only one brake light is out, it’s usually a sign of a burned-out bulb. Replacing the bulb should fix the issue. If the problem persists, it could be a wiring or socket issue.
![2024 Top Motorcycle All System Diagnostic Tool [We have tesed]](http://www.ancel.com/cdn/shop/articles/Black_and_Red_Racing_Team_Logo.png?v=1726657532&width=1){kind=logo}
