today i faced another problem i just try to start my car but, due the dead 12v battery it didn't start so i pressed the BRAKE PEDAL until it reach the bottom, again i tried to press but its not going to the bottom why was that, is it due to dead battery? And last time i called an automobile expertise to jump start my car. he check the voltage with a digital multimeter and he said me if you jumpstart even you will get this problem again until u replace the new battery. but i said him it doesn't matter do a jumpstart and finally it was ok . now again i faced the same problem and this time i am going to change the battery.
The brake pedal response changed because you were using up the reserve of pressurized fluid. With the battery dead the pump in the booster couldn't replenish it. Go ahead and get a new battery.
