Has this ever happened to you? You get in your car, hit the brakes, and then notice your brake lights are staying on—even when you’re not braking. At first, it may not seem like a big deal. But over time, brake lights that remain illuminated can create safety issues on the road and drain your car’s battery.
So why exactly do brake lights get stuck on, and how can you diagnose and fix the problem?
Having your brake lights randomly stay on can stem from various electrical issues, faulty components, and wiring problems in your car’s brake light system. While it may seem like a nuisance, continuous brake lights can end up causing bigger headaches down the road. Let’s cover the main culprits of why your brake lights are getting stuck on and how you can troubleshoot the root cause, so you can get your car’s brake lighting system back to working properly again.
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The 9 Most Common Reasons Why Brake Lights Get Stuck On
The specific reason your brake lights are staying illuminated varies depending on the make and model of your vehicle. However, there are some general issues that tend to commonly cause brake lights to stay on across all types of cars. Here are the top 9 culprits:
1. Faulty Brake Light Switch
One of the most common reasons your brake lights remain on is a glitchy brake light switch. This is the switch that activates the brake lights when you press down on the brake pedal.
If the switch malfunctions or fails to deactivate properly when you release the brakes, it will tell the lights to stay on even when you’re not braking. A faulty switch often needs to be replaced.
2. Problems With the Brake Pedal
Issues with the brake pedal itself can also cause the brake light switch to stay activated. For example, a stuck brake pedal that’s physically jammed in the pressed position will keep the switch on.
Other brake pedal problems like a stretched return spring, disconnected linkage, or misaligned stop can prevent the pedal from fully returning after braking, fooling the switch into thinking the pedals are still pressed down when they’re actually not.
3. Failure of the Brake Light Relay
There is also a relay that controls power to the brake lights. If this relay fails or gets stuck, it can continuously send voltage to the brake lights even when it’s not supposed to, resulting in illuminating the lights at all times.
4. Electrical Short Circuit
One of the wires that runs from the brake light switch to the lights themselves has likely shorted out. This creates a constant completed circuit back to the brake lights which keeps them powered on, even without pressing the brakes.
5. Blown Fuse
While less common, a blown fuse related to the brake lights could also be the culprit of illuminated brake lights.
When a fuse blows, it stops actively protecting that circuit. This can sometimes result in continuous power still getting through to the lights and keeping them on, even though the underlying electrical issue is not actually fixed.
6. Faulty Brake Light Bulb
Bad filaments or electrical shorts within the physical brake light bulb itself can also cause a bulb to stay powered on even when it’s not supposed to be.
If the bulb has an internal electrical issue causing part of the filament or wiring to essentially “stick” on, that can result in a false completed circuit back through the lights.
7. Loose Battery Terminal Cable
Loose battery connections seem totally unrelated to your brake lights. However, a loose negative battery cable can inadvertently result in continuous power flowing to the brake lights and keeping them illuminated.
This unintended constant power stems from an incomplete circuit when the cable is loose. Tightening the battery terminals may fix the problem.
8. Bad Ground Connection
The ground connection point that completes the circuit for the brake lighting system can also become corroded or loose over time.
A bad ground can cause unintended continuous power flow resulting in stuck brake lights that stay on even when not braking.
9. Aftermarket Alarm or Stereo
If an aftermarket alarm, stereo, or other electrical accessory was installed improperly, it can cause shorts and electrical gremlins that make the brake lights stick on.
The extra installation and wiring required for these extras can lead to shorts, unfinished circuits, and other problems if not done properly.
How to Diagnose and Fix Brake Lights That Won’t Turn Off?
Now that you know the most common reasons brake lights can get stuck on, here is a step-by-step approach you can take to diagnose and fix the problem:
Step 1: Inspect the Brake Pedal and Switch
Start your diagnosis by taking a close look at the brake pedal and switch. Check for any visible damage, sticking, bent parts, or misalignment that could cause the switch to stay activated even when you’re not braking.
Try pressing the pedal and watch to see that it fully returns into the rest position when released. Also try tapping the brake light switch to see if the lights turn off.
Step 2: Check Bulbs and Fuses
Next, inspect all the brake light bulbs themselves. Replace any that appear damaged or burnt out. Also check the fuse box and swap out any blown fuses related to the brake lights.
Sometimes bad bulbs or blown fuses can allow unintended power to continue flowing to the lights. So replacing them is an easy first troubleshooting step.
Step 3: Test for Electrical Shorts
If the brake lights still stay on, use a multimeter to test the electrical system for any shorts in the wires leading to the brake lights. You’re checking for any unexpected completed circuits that could be feeding the lights constant power.
Also check for bad grounds that can cause similar issues. Measure resistance between ground connections to confirm they are intact.
Step 4: Inspect Battery Terminal Cables
Take a look at the battery terminals and cables. If the connections are loose or corroded, tighten and clean them. Loose battery cables are a surprisingly common reason for stuck brake lights.
Step 5: Reset Electrical Systems
Sometimes resetting the electrical system can clear any stuck switches, relays, or shorts that are causing the problem. To reset, disconnect the battery cables for a minute or two.
You can also try disconnecting the connector to the brake light switch to reset its position. Also, reset any aftermarket alarms or radios by disconnecting the battery.
Step 6: Replace Any Faulty Components
If you’ve diagnosed the culprit, now replace any malfunctioning brake light switches, relays, fuses, bulbs, or wires causing the issue. New electrical components should stop the stuck brake lights.
Step 7: Seek Out Professional Diagnosis
If you still can’t resolve stuck brake lights after methodical troubleshooting and repairs, then it’s time to take your car to the pros. Dealership mechanics or trusted local auto repair shops have high-tech diagnostic tools to pinpoint any issues.
Continuously illuminated brake lights can be a nuisance, safety hazard, and battery drain. But in many cases, the cause of stuck brake lights turns out to be a simple fix like a faulty switch or loose wire. Following the strategic troubleshooting steps above helps isolate the root cause so you can get your car’s brake lights working properly again.
Thoroughly inspecting the brake pedal, testing electrical circuits, replacing bad components, and resetting the system often does the trick. But if your brake light gremlin persists, don’t let the problem linger too long. Seeking professional diagnostic services can help get your car safely back on the road and avoid bigger headaches down the line.