Squeaking brakes can be very annoying. It usually makes people turn their head an look at you providing some embarrassment. There are a few reasons your Brakes are making noise and some are simple fixes.
Squeaking after it rained or visiting the car wash
Brake pads sometimes make noise after they get wet. The moisture gets into the brake pad itself and causes the brakes to squeak and make a groaning noise. When this happens the noise will disappear after a few stops. The brake pads actually heat up and causes the moisture to evaporate. There is also another reason this happens after it rains or you visit a car wash. Sometimes there will be a layer of surface rust on the Brake Rotor and after a few stops the rust will be removed by the Brake Pad. These types of noises are considered normal for brakes to make because they disappear after 2 to 3 stops.
Constant squeaking when pushing on the brake pedal
Constant squeaking when pushing on the Brake Pedal can be caused by a few things. One of the first reasons is the make up of the brake pads. Brake pads are made up of ground up non flammable items that are meant to cause friction between the Brake Pad and the Brake Rotor. Some times during the manufacture of the brake pads an extra hard piece of something may be in the pad causing a squeak. The tell tale sign of this is grooves in the Brake Rotor. The repair for this situation would be to replace the brake pads.
Another reason they may squeak when pushing the brake pedal is the lack of lubrication on the brake pad. For brake pads to operate properly the Brake Pads need to be able move inside the bracket that holds them. If the Brake Pads were installed into the bracket without grease being applied they would make a squeak noise as the pads moved inside the bracket. The best way to remedy this situation is to take the Brake Calipers off and lubricate the brake pads.
The third reason is failing Brake Calipers. General Motors Trucks are most well known for this. The way the brake caliper is designed it has a piston with a rubber seal around it to create a seal inside the caliper housing. Over time the seal becomes dry and it makes a squeak noise when you push on the brake pedal because the piston moves. The way to correct this is to rebuild or replace the brake caliper.