Re: "Brake Pressure" warning - 91 750IL (archive)

I believe the symptom of fading pedal is the master cylinder. The accumulator, if bad, will seem fine unless you have to hit the pedal hard, at which time it will seem to not go down at all, then slowly go down and stop normally. I think you only have a master cylinder problem. As it sinks near the bottom, pump it a time or two and you should get some pedal back so you can stop, but then it will sink to the floor again. Be careful until its replaced.
Good luck.
Lin Gilbert
1990 750iL

I have been BMW owner for about a month now. And I am attempting to bring my 91 750IL back to the condition it should be in. I don't know enough about the many complex systems of the car yet. But I am learning. I have read almost every message posted here especially if it has to do with the brake system.

I have recently seen a message on the dash message system that is indcating "brake Pressure - See owners manual". This started about a week ago and I would like to get the groups feedback b4 I spend lots of money trying to fix the yet to be identified problem component(s).

Brake pedal pedal pressure/resistance fades as you increase effort and almost seems to go away completely near the floor. I can find no leak in the hydro system nor in the brake system. So my guess is the master cylinder is "bleeding pressure" past the "cups". Or it is the brake accumlator I should suspect (which is sealed? thus I would see no leak right?). Or the brake hydro booster?

I would love if someone could point me to a site that would explain the functions of the brake accumulator and the brake hydro booster.

I am thinking of replacing the brake accumulator and master Cylinder.

Is this a good plan?

Thanks for your help and advice
Sidney B. Nice

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