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      11-07-2011, 05:13 AM   #72
serranot
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Drives: 2011 E90 M3 6MT
Join Date: Mar 2011
Location: Falls Church, VA

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2011 BMW E90 M3  [5.00]
Quote:
Originally Posted by davem3fan View Post
I believe this one is the brake booster using a pump to
pressurize the brake system fluid in the lines.

There is a noticeable correlation between front brake pad wear/thickness and how long that pump operates on startup.
I believe this is the ABS self-test.