I just recently noticed this and want to make sure it's normal. If I press the brakes quickly there is a swoosh of air that sounds like it is coming from the pedal (like from a bicycle tire pump). But only if I press quickly. I usually drive like grandpa Jones so everything is nice and easy for me so I never noticed it, especially with the music on. Does everyone else hear this when they are driving and depress the brakes fast? Brakes work absolutely fine though and are not spongy. I had a tacoma the last 10 years and never noticed this noise. Don't know if its a jeep thing

 

This is completely normal, happens on all modern vehicles. There's a vacuum-assited brake booster that makes the pedal easier to push, and that's the sound of pressure leaving that system.

 

Thanks for the quick response to my noob question. Like I said I'm coming from a Tacoma I have had for the last decade, and guess im just not used to the jeep sounds, lol.

 

Mine makes a rubber rubbing sound. I havent had time to even look under there to see where/what is causing it.