Dash Brake Light

[Josie D]

Hi all, I have a problem, I have an Avensis estate 2004 D-4D, the other day while driving I went to brake found pedal went to the floor, did it again and brake went very hard but stopped the car,at the same time the brake light came on for a few seconds on the dash, then went off, since then tried to find the problem checked all brake pads they are fine, did a full brake fluid change everything ok apart from when I touch the brake the light still comes on the dash, when car is at a standstill and rev the engine the light goes off but when at tick over it remains on again for a few seconds. Can anybody please shed some light on what I should check next. Thanks Josie

[PATD]

Check vacuum pipes to brake servo for cracks.

[Josie D]

Hi, thanks for the reply, will check this out tomorrow. any other ideas, thanks

[Josie D]

I have been told it sounds as though it may be the Master Cylinder/Servo????? Does this sound right? Is this easy to replace?