How to Diagnose a Hard Brake Pedalby Contributor
Sometimes you may find that the brake pedal is acting a little strange and feels "hard." This is something that should be examined as it would not be safe to drive in a vehicle with faulty brakes. Here we will detail two possible causes for a hard brake pedal and the possible solution. If this is not the answer, then consult with a trained mechanic.
Brake Power Booster
Check the brake power booster by pumping on the brake pedal while the car isn't running. Continue pumping until you've "bled off" the vacuum from the booster.
Hold the pedal down while you start the car. The pedal should go down a bit more beneath your foot. If it doesn't, then you should examine the connection between the vacuum hose of the brake power and the engine's vacuum.
Replace the brake power booster if the connection's fine, which would fix the hard brake pedal problem.
Check the components of the caliper for any wear.
Look at the metal spring where the brake pads sit.
Apply tension to the pad and see whether you hear a pop. If you do, the brake pad is moving too much on the bracket. Replace the caliper. This could help the hard brake pedal.