Brake Lights Won't Go Off: Causes & How to Fixby Josh BoydUpdated September 09, 2022
Once every so often, a vehicle will do something quirky that leaves us confused. One scenario that illustrates this point quite well is when your brake lights won't turn off, even at times when they should not be lit. This problem tends to go from baffling to concerning in rapid succession when your vehicle's brake lights are the source of your issue.
If your vehicle's brake lights stay on, you are not alone. Fixing this issue is simple, and the following guide will provide you with the very details required to do so.
Why Do My Brake Lights Stay On?
When your brake lights won't turn off, the most likely cause is a faulty brake switch.
This particular switch is mounted below a vehicle's dash, in direct line with the brake pedal. Whenever a driver depresses their vehicle's brake pedal, this switch makes contact and distributes a positive or negative signal (depending upon the vehicle) to the brake lights, forcing their illumination. If this switch fails, the affected vehicle's brake lights will often fail to de-energize.
Here are some other potential reasons that your car brake lights won't turn off:
- A broken or damaged brake switch actuation bumper
- ACAN-BUS (electrical communication) malfunction
- A stuck brake pedal
Proper diagnosis will be required to determine the true source of the issue at hand, in each particular case.
How Do You Fix A Brake Light That Doesn't Turn Off?
Now that you have a better understanding of what causes brake lights to stick, you might find yourself wondering how you address the problem. However, before you can properly fix such an issue, you must first determine its root cause. By thoroughly diagnosing this fault, you will be better equipped to make a sound repair.
Follow the steps below to fix your brake lights that won't turn off:
- Check Brake Pedal Clearance: Begin by making sure that nothing is binding your vehicle's brake pedal, preventing it from returning to the rest position. Unsecured brake floor mats are a prime culprit behind issues of this type. Also, check to see if your car's brake pedal can be fully depressed and returned to its rest or stop position without any binding of the pedal linkage.
- Inspect Brake Switch: If your inspection during Step #1 revealed no issues, carefully check your vehicle's brake switch for signs of damage, or loose electrical connections. This switch will be located beneath the dash, inline with the brake pedal linkage. Likewise, inspect all associated wiring for signs of damage.
- Check Switch Continuity: You can quickly check to see if your vehicle's brake switch is stuck with the use of an ohmmeter. Simply disconnect the attached wiring connector from this switch, before checking to see if continuity is made and broken when depressing and releasing the brake pedal. The exact procedure for this test can be found in most model-specific service manuals. A lack of change in continuity would indicate a failed switch.
- Consult Vehicle-Specific Testing Procedures: If all has checked good to this point, you will need to consult factory-specific service literature for your particular vehicle, in a bid to locate CAN-BUS testing procedures. In most cases, diagnostics of this degree will require the use of a quality OBD-II scanner.
Things You'll Need
- Socket set
- Stoplight switch
- Stoplight switch stopper
Josh Boyd is an ASE certified, career automotive technician with an intense passion for all things of mechanical nature. Whenever Josh does not have a wrench in his hand, he can be found writing for multiple publications.