If turn signals work but brake lights do not, it may indicate a faulty brake light switch. This component is responsible for activating the brake lights when the pedal is pressed.
Driving with malfunctioning brake lights can lead to dangerous situations on the road. While you may notice your turn signals work fine, having non-functional brake lights is a common problem faced by many drivers. This issue is not only frustrating but also unsafe and illegal in many places. Understanding the causes and knowing how to fix it is essential.
Ignoring malfunctioning brake lights can pose a significant risk to both the driver and other road users. In the following sections, we will explore potential causes and solutions for this common automotive issue.
Credit: www.ford-trucks.com
Contents
How Turn Signals and Brake Lights Work Together
Before diving into the causes and fixes, it’s important to understand how brake lights and turn signals are wired. Both brake lights and turn signals share the same light housing in many cars, especially in older models. This design is called a “dual-filament” or “shared-bulb” system, where one filament in the bulb is for the brake light and the other is for the turn signal. When one function stops working (such as the brake light), it’s often due to an electrical or wiring issue affecting that specific function.
Common Causes of Brake Light Failure
Common causes of brake light failure include:
1. Blown Brake Light Fuse
One of the first places to check when your brake lights fail is the fuse. A blown fuse will prevent power from reaching the brake lights while allowing other systems, like the turn signals, to operate.
- Symptoms: Turn signals work but brake lights don’t. All brake lights fail, not just one side.
- Solution: Inspect the brake light fuse in the fuse box, usually located under the dashboard or in the engine bay. Replace it with a fuse of the same amperage if it’s blown.
2. Faulty Brake Light Bulb
A blown or faulty brake light bulb is one of the most straightforward issues to diagnose and fix. The filament inside the brake light portion of the bulb may burn out, while the turn signal filament continues to work.
- Symptoms: Only one brake light doesn’t work, while the turn signals are functional.
- Solution: Inspect the brake light bulbs. If the brake filament is broken, replace the bulb.
3. Bad Brake Light Switch
The brake light switch is located near the brake pedal and activates the brake lights when you press the pedal. If this switch malfunctions, your brake lights won’t illuminate, even though your turn signals continue to work.
- Symptoms: Brake lights fail on all sides. Other lights (like the third brake light) may also stop working.
- Solution: Inspect and, if necessary, replace the brake light switch. You can find it at the base of the brake pedal arm.
4. Faulty Turn Signal Switch (Multifunction Switch)
In some vehicles, the brake lights are wired through the turn signal switch, also known as the multifunction switch. If the turn signal switch is faulty, it could interrupt the flow of electricity to the brake lights while leaving the turn signals operational.
- Symptoms: Brake lights fail, but turn signals work. Sometimes, other functions controlled by the multifunction switch (like hazard lights or wipers) may also fail.
- Solution: Replacing the turn signal switch usually resolves this issue. However, this can be a more complex repair that might require the steering column to be partially disassembled.
5. Corroded or Faulty Ground Connection
Electrical systems require a good ground connection to function properly. Corrosion, rust, or a loose ground wire can interrupt the flow of electricity to the brake lights, while other systems like turn signals continue to work.
- Symptoms: One or both brake lights fail intermittently, while turn signals remain functional.
- Solution: Inspect the ground connection near the brake lights for corrosion or loose connections. Clean or tighten the ground wire as needed.
6. Broken Wiring
Over time, wiring harnesses can become damaged, worn, or frayed, especially in areas prone to moisture or vibration. A broken wire in the brake light circuit can cause the brake lights to fail, while the turn signal wiring remains intact.
- Symptoms: Brake lights don’t work, but turn signals function normally. Other electrical issues may also appear.
- Solution: Inspect the wiring leading to the brake lights for visible damage, breaks, or wear. Repair or replace damaged sections as necessary.
7. Faulty Bulb Sockets
Bulb sockets can corrode, especially in vehicles exposed to moisture or road salt. A corroded socket may prevent the brake light from receiving power, even if the bulb itself is fine.
- Symptoms: Brake lights may flicker or fail to work, while turn signals remain unaffected.
- Solution: Inspect the bulb sockets for signs of corrosion or wear. If corrosion is present, clean or replace the socket.
8. Bad Relay or Flasher Module
In some vehicles, the brake lights and turn signals share a relay or flasher module. If the relay fails, it can cause issues with the brake lights, though the turn signals may still function.
- Symptoms: Brake lights fail, but turn signals work normally. Intermittent electrical problems may occur.
- Solution: Check the relay or flasher module associated with the brake lights. Replace it if it’s faulty.
Diagnosing the Problem
When dealing with brake light issues, it’s important to follow a logical sequence of checks to identify the cause of the problem. Here’s a step-by-step guide for diagnosing why your turn signals work but the brake lights do not:
- Check the Fuse: Open your vehicle’s fuse box and inspect the brake light fuse. If it’s blown, replace it with a fuse of the same amperage.
- Inspect the Bulbs: Remove the brake light bulbs and check for a burned-out filament. If the filament is broken, replace the bulb.
- Test the Brake Light Switch: Use a multimeter to check the brake light switch located near the brake pedal. If it’s faulty, replace it.
- Examine the Wiring and Sockets: Inspect the wiring harness and bulb sockets for signs of damage, corrosion, or loose connections. Repair any damaged wiring or clean corroded sockets.
- Check the Turn Signal Switch (Multifunction Switch): If all other components seem fine, the issue may lie with the turn signal switch. This will require testing or replacing the switch.
Preventing Brake Light Issues
Prevention is key to avoiding brake light failures in the future. Here are a few tips to keep your brake lights functioning properly:
- Regularly Inspect Bulbs: Periodically check your brake light bulbs for signs of wear or burnout.
- Keep Sockets Clean: Clean bulb sockets to prevent corrosion from developing.
- Maintain Electrical Components: Inspect wiring and fuses regularly to catch any signs of damage or wear early on.
- Address Moisture Problems: If you notice condensation or moisture inside your light housings, seal them to prevent corrosion.
When to Seek Professional Help
If you’re unable to identify or fix the problem with your brake lights, it may be time to seek professional help. Electrical issues in vehicles can be complex and sometimes require specialized tools and knowledge to diagnose and repair properly. A qualified mechanic or auto electrician can use diagnostic tools to pinpoint the problem quickly and safely.
Frequently Asked Questions
Here are some FAQs about the brake light issues –
1. Why do my turn signals work but not my brake lights?
This issue is often caused by a blown fuse, a faulty brake light switch, or a bad brake light bulb. It could also be due to wiring issues or a malfunctioning turn signal switch that interferes with the brake light circuit.
2. How do I check if my brake light fuse is blown?
To check the brake light fuse, locate your vehicle’s fuse box (usually under the dashboard or in the engine bay), find the fuse labeled “brake lights,” and visually inspect it for any signs of damage. If the metal strip inside the fuse is broken, replace it with a fuse of the same amperage.
3. Can a bad brake light switch cause my brake lights to stop working?
Yes, a faulty brake light switch can prevent the brake lights from illuminating when the pedal is pressed. The switch, located near the brake pedal, may need to be adjusted or replaced if it’s not working properly.
4. How much does it cost to fix brake lights?
The cost of fixing brake lights depends on the issue. Replacing a bulb typically costs less than $20, while fixing wiring or replacing a brake light switch can cost $50 to $150. More complex electrical issues involving the turn signal switch or wiring harness may be more expensive.
5. Can I drive with my brake lights not working?
Driving with non-functional brake lights is illegal and unsafe, as other drivers won’t be alerted when you stop. It’s crucial to fix the issue immediately to avoid accidents or traffic violations.
Conclusion
If your turn signals work but your brake lights don’t, the issue could stem from a variety of causes such as a blown fuse, faulty brake light switch, or wiring problems. By systematically inspecting and diagnosing the problem, you can restore your brake lights to working condition and ensure your vehicle is safe for the road. If you’re unsure about the repair process or unable to resolve the issue, don’t hesitate to seek professional help. Properly functioning brake lights are essential for safe driving and legal compliance.