Disc Brake Wear Sensor
When brake pad wear reaches a point where it needs to be replaced, a steel clip will make contact with the brake rotor, producing a squealing noise alerting the driver that the brake’s linings are worn out and need to be replaced. If you’re hearing this sound and delay fixing your brakes, you will soon hear a grinding noise. At this point, both the brake pads and the brake rotor will need replaced.
On some luxury vehicles, an electronic brake wear sensor system replaces the steel clip brake wear sensor. This system uses an electrical circuit designed to alert the driver with a message on the instrument panel when the brake pads need to be replaced.
Did your brake pedal feel like a drum roll the last time you pressed the brake pedal? If so, you're experiencing brake pulsation, a condition that happens when the brake rotor is warped and needs to be resurfaced or “turned”.
If the brake pad makes contact with the brake rotor and it is not a completely flat surface, the vibrations in the brake rotor will be multiplied through the brake pedal. This is not a safety issue, but it is very annoying.
If you feel a vibration in your vehicle every time you come to a stop after a brake job, take the vehicle back to the shop and ask for new rotors. While your mechanic is working on your brakes, they may ask if you would like your rotors or drums turned. When your rotors are turned, it means that they are shaving off a small amount of metal from the rotor to make sure the surface is smooth, which will improve brake pedal feel and reduce vibrations. Rotors that have been resurfaced too thin can be very dangerous.
If your rotors are too thin and you make an emergency stop, the rotors may warp or even crack. The mechanic should measure the brake rotors with a micrometer to see if the rotors are within the manufacturer’s specifications. (See picture below) If the brake rotors are not within the manufacturer’s specifications, it is recommended that they be replaced. Some “mechanics” do not offer to replace brake rotors because the price can be hard to sell to their customer.