[ccyphers]

Hey folks. My wife’s 99 Camry recently started making a hissing noise near the brake pedal area. It started hissing when she pressed on the brakes but has since started hissing all the time…..when her foot is on and off the brake. I tried pumping the brake with the car turned off to build up pressure, kept my foot on the brake and started the car and the pedal went almost to the floor. I checked under the dash and the sound is coming from the pedal area. I also checked under the hood and the sound seems to be coming from the brake power booster area. Upon putting my ear closer to the booster in the engine compartment, the sound seemed to be more towards the engine and maybe not from the booster itself. Kinda hard to tell where the sound is coming from under the hood with the engine running.
1. Does this sound consistent with the power brake booster being bad?
2. If it is the brake booster, how difficult is it to replace for a simple do-it-yourselfer?
3. Anyone know of the typical cost to have one repaired at the dealership?