I have a 2004 GMC Envoy. I replaced the brake pads the other day, and when I was pumping the brake pedal restore pressure on the calipers, I noticed kind of a whooshing sound. I did not drain or replace the brake fluid, just changed pads. The pedal only makes this sound when I'm not moving and I push the pedal down. The brake light is not on, and it drives and brakes perfectly. Is this sound like a pressure release that activates when you push the brakes all the way in when you aren't moving? I don't know that I ever tried pushing the pedal down in the past while at rest other than just touching it when I shift into gear. The noise only happens when I push down kind of far on the pedal.
