You want your vehicle's brake pedal to provide consistent feedback when applying pressure to your brakes. If the pedal changes from a stiff feeling to one that is loose, it's a big warning sign that your vehicle has brake problems. Before you head out to a local mechanic to diagnose the problem for you, it will help to troubleshoot it on your own. You may find out that fixing the problem is simpler than you think.
If the brake pedal is feeling loose when you press it, you likely have a problem with the brake fluid. You'll want to go under the hood of your car and look closely at the fluid levels. There should be a light that indicates that the fluid is full. Having any amount of fluid below the fill line isn't good for your brakes. Add more fluid, replace the cover, close the hood, and see if that does the trick of fixing your problem.
Having pockets of air within your brake lines can cause disruption to the amount of pressure in the hydraulic fluid system. It can result in the brake pedal feeling loose when you apply pressure to it. The trick to fixing a problem with air pockets is to bleed the vehicle's brake lines.
Put the car up in the air on a jack to access the system's bleeder valve, which is located behind the tire. Place a tube on the valve that directly into a small container. Use a wrench to loosen the valve and allow the air and hydraulic fluid to come out. It will help to have another person put pressure on the vehicle's brake pedal to help move hydraulic fluid through the lines. You essentially pump the brakes until air bubbles are no longer in this hose, then repeat the process for each tire's brake lines.
Damage Brake Lines
It is also possible that the vehicle's brake lines are cracked or damaged. A small hole is all it takes to allow the brake fluid to leave the system, resulting in a soft brake pedal. Try to look for brake fluid in your driveway where you park your car to verify that you have damaged lines. You'll then want to take your car to a local auto shop to have your brake lines repaired. You'll be back on the road with responsive brakes in no time.
If you think there is an issue with your brakes, contact a company like Dualtone.