Here are Some Signs of Brake Problems
If you ever heard a high-pitched screeching sound when you applied your brakes, that's a small metal shim, called an indicator, that is telling you it's time to replace your pads. If you hear it regularly, you should make an appointment with your mechanic.
If your brakes are not as responsive as they should be or if the pedal 'sinks' toward the floor, this is an indication there may be a leak in the system.
A vibration on the brake pedal is often a symptom of warped rotors. Warped rotors are caused by braking for long periods. They heat up and cause the rotors to warp.
A grinding metallic sound usually means that you have worn off the pads or worn them down. The grinding noise is actually two pieces of metal rubbing together. This can scratch your rotors, creating an uneven surface.
If you experience any of these, you should contact a repair shop as soon as possible.