Common Causes:
* Low Brake Fluid: This is the most common reason. Check the brake fluid reservoir (usually a clear plastic container near the master cylinder under the hood). If it's low, you have a leak somewhere in the brake system which needs immediate attention. Do not drive the vehicle until this is addressed.
* Brake Pad Wear: Worn brake pads trigger a sensor that illuminates the brake light. This is a less urgent issue than low brake fluid, but still needs attention soon.
* Faulty Brake Light Switch: This switch is located near the brake pedal and activates the brake lights when the pedal is pressed. If it's faulty, the lights might not work correctly or the warning light might stay on even when the brake is not applied.
* Faulty Brake Light Bulb(s): While a burnt-out bulb wouldn't directly cause the brake light warning to come on, some systems will interpret a failed bulb as a problem within the braking system itself. Check all your brake lights (including the center high-mounted stop lamp - CHMSL, often called the third brake light).
* ABS (Anti-lock Braking System) Problem: The brake light often acts as an indicator light for the ABS system as well. A problem with the ABS module, sensors, or wheel speed sensors can illuminate the brake light. This usually requires a diagnostic scan tool to pinpoint the issue.
* Parking Brake Engaged: A simple oversight! Make sure your parking brake isn't partially or fully engaged.
Less Common Causes:
* Wiring Issues: Damaged or corroded wiring in the brake light circuit can cause malfunctions.
* Master Cylinder Issues: Problems with the master cylinder itself can lead to low brake fluid and the brake light illumination.
* Electronic Control Module (ECM) problems: In rare cases, a malfunctioning ECM could trigger the brake light warning.
What to Do:
1. Check the brake fluid level immediately. If it's low, do not drive the vehicle. Have it towed to a mechanic.
2. Inspect the brake pads. If they're worn, they need replacing.
3. Check all brake light bulbs. Replace any that are burnt out.
4. If the problem persists, have the vehicle scanned with an OBD-II code reader or take it to a qualified mechanic. They can diagnose the exact cause and make the necessary repairs.
Ignoring a brake light warning is dangerous. Address this issue promptly for your safety and the safety of others.
