Check around brake pedal for something rubbing. If OK, I'd look into the master cylinder.
YES-IF IT has a vaccume booster & not Hydro or air brakes
The Parking Brake has a couple of configurations, on some vehicles with rear disc brakes it will press the inside pad of the caliper and squeeze the pad against the brake rotor to engage, some vehicles have a small set of brake shoes inside the rear rotor hub which press against the hub and prevent it from turning when the brake lever is engaged. On vehicles with rear drum brakes, the parking brake causes the rear brake shoe on either side to press against the brake drum and prevent it from turning. Either configuration in on the rear wheels.Usually the rear axle. The parking brakes are also the emergency brakes, and if they were on the front, could render the vehicle unsteerable in an accident avoidance maneuver.Rear brakes. On some older cars they parking brake actually surrounded the drive shaft and when applied lock the drive shaft in place. Today the parking brake applies the rear brakes.
Brake fluid in reservoir below acceptable level.
If the tire locks up when you apply the brakes and you have drum brakes then you may have brake fluid leaking onto the brake shoes. If you have ABS then you may have a bad wheel sensor. The adjusters on the brake shoes are out of adjustment or broken. Springs or hold down hardware may be broken. Cracked brake linings. Backing plates are worn out.
Either warped rotors or drums can cause pulsating. Apply the parking brake slowly while going about 15mph and see if t pulsates. If it does, it is the drums that need turning. If not, it is the rotors that need turning.
un equal adjustment of brakes will cause one brake to apply earlier and harder than other brake
If the brakes on a Mazda 6 are squeaking, it could be indicative of a problem. The brake pads could be incorrectly set.
Only use products designed to clean brakes. Most auto parts stores carry brake cleaner. If you use anything else it could leave a residue that could cause your brakes to fail.
There are a lot of different things that could be wrong. But initially what it means is that your brakes are going out or are out You should start by checking your brake fluid if that is low it would cause you to loose pressure. If your brake fluid is low and you fill it things should get better if you don't have a hole in your brake line. If the fluid is full check your brake pads
Usually, a loss of pressure in your brake system means that there is a hole somewhere in the system. A leaking brake line or a punctured reservoir could cause a loss of pressure. A bad master cylinder could also cause a loss of pressure in the back brakes.
The cause can be traced to a few things. Number one the master cylinder may have failed. Number two you could be low of brake fluid or have none at all due to a leak or broken brake hose. If the power brake booster fails you may think you do not have brakes because it requires an excessive amount of pressure on the pedal to activate the brakes. Whatever the cause do not drive this car into you have the brakes repaired.
Could be low on brake fluid. If it is low you either needs brakes or you have a leak in the system.
brake caliber
It could be a bad cylinder, bad springs, bad emergency brake, or could need to be adjusted.
Probably a rotted out brake line sprung a leak, check the brake fluid reservoir.
worn front end parts (steering or suspension) could cause a car to shake when appling the brakes.
Accumulation of brake dust over time will cause the calipers to stick and the brakes will heat up from the friction. They might need cleaning and relubing. Driving with your foot resting on the brake pedal will also do it.