* Low Brake Fluid: This is the most frequent culprit. Check your 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 your braking system – a serious issue requiring immediate attention. Do not drive the car until this is fixed.
* Brake Light Switch: This switch is located near the brake pedal and activates the brake lights when the pedal is pressed. If it's malfunctioning, it might be stuck "on," constantly sending a signal to illuminate the lights. This is a relatively inexpensive and easy fix.
* Parking Brake (Emergency Brake): Make absolutely sure your parking brake is fully released. Sometimes a slightly engaged parking brake can trigger the brake light.
* Faulty Brake Light Bulb: While a burned-out bulb usually only affects one side, a short circuit in a faulty bulb could trigger the warning light for both. Check all three brake light bulbs (two on the rear, one on the center high-mounted stop lamp).
* Bad Brake Pedal Position Sensor: This sensor detects when the brake pedal is depressed. If it's faulty, it could send an incorrect signal.
* Wiring Issues: Damaged or corroded wiring in the brake light circuit can cause the lights to stay on. This could be anywhere from the switch to the bulbs themselves. Check for broken or frayed wires, particularly near the brake pedal and the taillight assemblies.
* Master Cylinder Issues: While less common than a low fluid level, problems with the master cylinder itself can also trigger the light.
Troubleshooting Steps:
1. Check the brake fluid level: This is the most crucial first step.
2. Release the parking brake fully.
3. Inspect all brake light bulbs.
4. Check the brake light switch: This may require some mechanical knowledge or a professional mechanic.
5. Visually inspect the wiring harness related to the brake lights: Look for obvious damage or corrosion.
Important: Driving with a constantly illuminated brake light is unsafe. Not only is it a violation of traffic laws, but it indicates a potential problem with your braking system. Have the issue diagnosed and repaired by a qualified mechanic as soon as possible. Don't attempt major brake system repairs yourself unless you have the necessary expertise and tools.
