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Discussion Starter #1
Hi all,

I've noticed that when depressing the brake pedal, there's an electric sound (hard to describe, almost like the sound of a CD ejecting or electric side mirrors being adjusted) coming from the dash area. It seems to only happen when first starting the car and the first couple minutes, but could be happening more and just not hearing due to road noise.

Anyone have an idea what it could be?
 

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Best guess is a leaking brake booster. It sounds more like air leaking/seeping. It would sound like it's coming from under/behind the dash and only when your foot is on the brake. If you lift your foot of the brake and it goes away, then it is definitely your brake booster.
 

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If I'm not mistaken there's an electric brake booster pump to increase efficiency until all systems are up and running. These have a tendency to make a buzzing sound, nothing to worry about.
 

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Vacuum Assist Pump
(or called something like that)

If the engine is not producing sufficient vacuum for the braking system the vacuum pump will engage to assist in maintain system vacuum. You can test its operation by having the key out of the ignition and depressing the brake pedal until stiff, then turn the key to position 2 and you should hear the pump engage and the pedal should travel to the floor.
 
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