brake problem s3

[builder al]

Hi lads Im still trying to find out what my brake problem is. I had the car plugged in for faults it came up with fault 00812 035 brake pressure solenoid -84- sporadic my ABS kicks in realy early it scares the **** out of me what does the solenoid pressure switch do. the car has a will of its own I know its not called Herbie and ideas lads would be helpfull not the name the problem

THANKS LADS