1. The Simple Checks (Easiest First):
* Bulbs: This is the most common cause. Check all three brake light bulbs (two on the back, one in the center high-mounted stop lamp (CHMSL) – often called the third brake light). Replace any burned-out bulbs. Make sure they're the correct type and installed correctly.
* Fuses: Check the fuse box (usually under the hood or inside the car, often near the steering column) for blown fuses related to the brake lights. The owner's manual will show you the fuse diagram.
* Brake Light Switch: This switch is usually located near the brake pedal. It's activated when you press the brake pedal. It's a relatively inexpensive part and easy to replace if it's faulty. You might be able to test it with a multimeter (if you have one) to see if it's providing power when the brake pedal is pressed.
* Tail Light Switch: While less common, a faulty tail light switch could affect the brake lights.
2. More Involved Checks (Requires More Expertise/Tools):
* Wiring: Check the wiring harness for any broken, frayed, or corroded wires leading to the brake lights. Look particularly at the connections at the bulb sockets and the brake light switch.
* Brake Light Switch Connector: Look for corrosion in the connector for the brake light switch. A simple cleaning might solve the problem.
* Grounding Issues: A poor ground connection can prevent the brake lights from working. Check the ground wires for corrosion or looseness.
* Brake Light Circuit: This is more advanced. You'll need a multimeter to trace the electrical circuit from the brake light switch to the lights themselves to pinpoint a break in the circuit.
* Body Control Module (BCM): In some cases, a faulty BCM can cause electrical problems, including brake light failure. This is a more complex issue requiring professional diagnosis.
Troubleshooting Steps:
1. Start with the simplest checks: Bulbs and fuses.
2. Inspect the brake light switch: Visually inspect for damage and test its continuity if you have a multimeter.
3. Check the wiring: Look for any obvious damage.
4. Check the ground connections: Ensure good contact.
5. If all else fails: Seek professional help from a mechanic.
Important Safety Note: Driving with non-functional brake lights is extremely dangerous. If you cannot resolve the issue quickly, do not drive the vehicle until it's repaired. Consider using hazard lights as a temporary (but less effective) measure.
