Brake Light Doesn’t Work When Headlights Are On (Troubleshooting Guide)
Is your brake light not working when headlights come on? If you’re experiencing this strange occurrence, you could be asking your many questions including why this happens and what you can do to fix it. Luckily, this article will help you out.
Brake light doesn’t work when headlights are on is mostly caused by a broken ground circuit. Other potential causes for this issue include blown brake light bulbs, malfunctioning brake light switch, incorrect bulb installation, blown fuse, turn signal switch malfunction, wiring issues, or even a defective light control module.
This article will take you through more in-depth details on why your vehicle brake lights fail to work when the headlights are on and how to fix this issue. We will also discuss why the lights only work headlights are off, and why only the brake light works when the headlights are on.
Why Your Brake Light Doesn’t Work When Headlights Are On
Here are the common reasons why your brake light doesn’t work when the headlights come on:
Broken ground circuit
The most common reason why your brake lights won’t come on when the headlights illuminate is due to a bad ground circuit.
Proper grounding is key to the proper functioning of various electrical components of your car, including the lights.
Inspect your car wiring harness for signs of damage, e.g. frayed wires, broken wires. In case you find any issues, make the necessary repairs and replacements.
Blown bulb
Another likely reason behind the light not coming on is a blown bulb. We advise you to inspect the brake bulb at the rear of your car to see if it’s burned out
If you find that the bulb is faulty, simply replace it with the correct one designed for your vehicle.
Wrong bulb installation
Yes, a wrongly installed brake light bulb can also cause the light not to come on when the headlights illuminate. If you had your brake bulb recently installed you’d want to access it and check if it was installed correctly. Remove the bulb and reinstall it the correct way to see if this solves the problem.
Faulty brake light switch
The brake light switch sits near the brake pedal and helps activate your vehicle brake lights whenever you press the pedal. However, if this switch is failing, it will not activate the lights when the headlights come on. Consider having your brake light switch inspected if you suspect it could be the cause of this problem.
Blown fuse
You may also want to check the condition of your brake light fuse. The fuse box is usually situated under your dashboard. If the fuse is bad, the only solution is to replace it with a new one. Make sure you get a new fuse that’s similar to the one that’s blown.
Wiring issues
If your car has developed any faulty wiring, it could also be the culprit behind the problem you’re facing. Bad wiring will interfere with electrical connection that exists between your headlight circuit and the brake lights. Be sure to inspect your car wiring harness for signs of damage corrosion, loose connections, etc., and fix them as necessary.
Malfunctioning light control module
A failing light control module in your car can affect the interaction between your headlights and brake lights. if you’ve still not found the culprit to this point, you may want to have the module tested by a qualified auto mechanic and replaced if necessary.
Issues with the turn signal switch
Some car models’ brake lights are part of the turn signal circuit. This means if the switch is broken, it may cause the brake light to stop working when the headlights are on. It’s therefore, important to inspect your switch diagram wiring for signs of damage.
What To Do If Brake Light Doesn’t Work When Headlights Are On
If your vehicle brake light doesn’t work when the headlights come on, you can carry out a diagnosis to find out what’s causing this problem.
Below, we have discussed helpful troubleshooting tips to help you out:
- Inspect the brake light bulb: take out the brake light bulb at the rear of our car and check if it’s damaged or burned. If yes, replace it with a new one. Replacing the bulb is a simple DIY task that you can carry out on your own.
- Ensure the bulb is correctly installed: you may also want to remove the brake light bulb and reinsert it correctly so that it sits properly in its socket.
- Take a look at the grounding connection: check the brake lights ground wire and ensure it’s connected securely and has no signs of corrosion. If necessary, clean up the grounding point to ensure a good connection.
- Check the brake light switch: You should also test the brake light switch to see if it’s in good working condition. An easy way to test this component is to use a digital multimeter. Alternatively, you can use this light bulb test method. If the switch is bad, simply replace it with a new one.
Here’s a quick video on how to test the brake light switch with a multimeter:
Video:
- Inspect the wiring: Check the wiring connected to your car brake light for any signs of damage e.g. broken or frayed wires. In case of any issues, be sure to replace or repair the problematic wiring as necessary.
- Get help from a qualified mechanic: If you try all the troubleshooting steps above but still can’t find a solution to the problem, then it’s time to get help from a qualified mechanic.
What If Your Brake Lights Only Work When Headlights Are Off?
In some cases, your brake lights will only work when the headlights are off. In this case, the most likely reason behind this issue is an electrical system problem with your car.
In most cases, your car may be having a bad ground connection to the bulb shell or to your car tail light assembly. (Source).
You may also want to check the brake light bulb socket and ensure the contacts aren’t touching each other or anything unusual that could result in problems.
You should also check the harness at tail light to ensure the wires are not shorting against each other.
Other areas to look into are whether all the other bulbs are correct, wiring problems, sockets, power supplies are sufficient, combination switch on the steering—look for anything that doesn’t seem right and could lead to problems.
If you check all these parts and they don’t solve the problem, you should have a certified mechanic perform a diagnosis on your car to help you figure out things.
Why Your Jeep Brake Lights Don’t Work When Headlights Are On
Jeep Grand Cherokee brake lights not working when headlights are on
If you own a Jeep whose brake lights fail to work when the headlights are on, the problem could be a burned-out brake light bulb or a wrongly installed bulb.
Other potential issues include a faulty brake light switch, grounding problems, malfunctioning light control module, or wiring issues.
You can follow the troubleshooting tips we discussed earlier to diagnose the exact problem your car is going through.
However, if you’re not comfortable doing this diagnosis, then you take your car to a certified auto mechanic to do it for you.
Why Is One Brake Light Not Working When Headlights Are On?
If one of your brake lights does not illuminate when your headlights are on, the problem could be caused by a bad bulb or incorrectly instated bulb.
Access the bulb that’s not illuminating and inspect it for damages. You can also try removing it and reinserting it to see if it will start functioning as intended.
Another reason why this is likely to happen is due to a bad socket. You may want to inspect the socket for the problematic bulb for signs of corrosion.
Clean it if you suspect it’s not making a proper connection with the bulb. You can also replace the socket with a new one.
Writing issues can also bring about this problem. We advise you to inspect the non-functioning bulb’s wiring for signs of damage, loose wires, frayed wires, etc. Ensure the connections are secure and corrosion-free.
Any damaged wiring should be repaired or replaced to help restore the bulb’s proper functionality.
Grounding issues could also be responsible for one of your brake lights not working when headlights come on. You should check the grounding for the non-functioning brake light and ensure it is securely connected and corrosion-free.
Above all, you may want to check if your brake light switch is in good working condition. Have the switch tested and replace it if it doesn’t seem to be in good working condition.
Why Do My Tail Lights Not Work When My Headlights Are On?
If your tail lights are not working when the headlights are on, the key areas to inspect include:
- Check for blown tail light bulbs
- Check for incorrectly installed tail light bulbs
- Inspect all the wiring connections for tail lights for signs of damage
- Faulty light switch that controls tail lights and headlights
- Check whether the fuses related to tail lights are blown
Is It Okay To Drive With No Brake Lights?
It’s not recommended to drive your car with no brake lights. Brake lights serve as a crucial safety feature that notifies other drivers behind you when you’re slowing down your car or making a stop. This helps prevent various accidents, such as getting rear-ended.
If your vehicle’s brake lights aren’t functioning, it means the other drivers won’t be able to know your intentions whenever you’re slowing down or stopping your car. This increases the risk of getting rear-ended as well as other accidents.
Overall, it’s a good idea to have your brake lights fixed as soon as possible if they start malfunctioning. This is important for your own safety as well as that of other road users.
Mind you, driving a car without headlights is regulated in certain jurisdictions and you may find yourself on the wrong side of the law.
If you’re experiencing a situation where the brake light doesn’t work when the headlights are on, you may also find our article on brake light won’t turn on helpful. This article provides troubleshooting tips and potential solutions for a brake light that fails to turn on. Additionally, if you’re noticing that the brake light comes on when accelerating, our article on brake light comes on when accelerating explores the possible causes and suggests steps to address this issue.FAQs:
Are brake lights connected to headlights?
No brake lights aren’t connected to the headlights. The two are separate lighting components designed to serve different purposes in your car lighting system
What fuse controls brake lights?
The fuse tasked for controlling brake light is the one labeled “stop lights” or “brake lights” and is located in the fuse panel/box. For more info concerning the specific fuse that controls brake lights, consult your vehicle’s owner manual.
Conclusion
It’s a common experience among various car owners for their brake lights to fail to work when the headlights are on. The most common causes for this issue include bad ground connection, blown bulbs, wrongly installed bulbs, wiring problems, faulty brake light switch, blown fuse, turn signal switch problems, and malfunctioning light control module.
Diagnosing your by paying close attention to these areas will help you easily uncover the underlying problem and do the necessary repairs or replacements to fix the problem. If you follow our troubleshooting guide above and can’t seem to find out what’s causing the brake lights issue, get a certified auto mechanic to diagnose your car.
