The noise is from a bypass valve that is part of the integrated pump the pressurizes the power steering and brakes.
It is common to have some hissing noises.
However, there is so much inter locked between the 2 systems, I am providing you with information on diagnosing each, noises diagnostics, diagrams, general desrptions of how they function together and how to repair the rare cases where there is a problems with a hissing noise.
Let me know if you have any questions or need any more information.
I will reply ASAP as I check posts for replies often.
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Thursday, October 13th, 2011 AT 2:32 AM