Failed Master Cylinder would be my guess. Replace the Master Cylinder.
If the pedal firms up after pumping a few times, its probably air in the lines. Bleed the brakes. If this does not solve the problem look for leaks and record your symptoms in detail to tell your mechanic and go see him soon!
Check you brake fluid and lines. It may be as simple as bleeding your brakes.
the master cylinder is whats bad
Light is usually comes on, when there is a problem with pressure in brake lines. Inspect the brake fluid level, and check for leaks.
If brakes lock up on a 1999 Hyundai Sonata there may be a problem with one or more of the brake components. Improper brake fluid mixture or leaks in the lines will cause the hydraulic calipers to malfunction. The entire brake system should be checked for the safety of the driver when dealing with this issue.
Also, no visible leaks in the lines, all brake pads were changed less than 4 months ago. Master Cylinder has been going dry in 2 days time, now there are absolutely no brakes after I filled it back up today.
Pinched or blocked transmission cooling lines
Did anybody bleed the brake lines? There is possibly still air trapped in lines and air compresses brake fluid does not.
You need to check all brake lines and look for leakage. Also you should check the main brake cylinder for leaks (you can find under the hood attached to firewall on the driver's side).
No. air in brake lines will cause you to have a mushy pedal or no brakes at all. normal causes for brakes to drag are either bad calipers/wheel cylinders or rubber brake lines to have deteriorated on the inside forming a kind of one way valve or the emergency (hand) brake cable is hanging up/frozen.
Probably not. The backfiring is usually caused by a lean condition. Check all your vacuum lines and gaskets for leaks.
Power loss on an engine is generally due to an air problem. Check the vacuum lines on the engine to see if there are any leaks. Leaks in a vacuum line cause a car to either run to lean or rich. This will negatively effect the performance of the car.