The power brakes on most vehicles operate on the engine vacuum. If there is a leak or problems with the power brakes it can make a hissing sound. But then, sometimes power brakes do that when they're working properly. It could be from either a hole in the diaphragm of the brake booster or normal operation. If the sound is new, and was not there before, and your brake pedal is going to the floor, then you should have the power booster replaced.
BEHIND THE BRAKE PEDAL
behind the brake pedal
the switch is on top back side of brake pedal.
Sounds like a Vacuum leak in brake booster.
Directly above the brake pedal.
top of brake pedal
I have a 97 Tahoe and the brake lights were not working and the problem was in the emergency flasher switch. I just jiggled it and the brake lights worked so am thinking you might have the same problem. It could also be the brake pedal switch located right on the pedal arm.
brake light switch, it is typically located above the brake pedal somewhere on the brake pedal arm
There is no such thing as an "Emergency brake" in a vehicle. The PARKING BRAKE is the pedal to the far left against the edge of the driver's footwell. The handle above the pedal is the release.
The vacuum selector switch on a 1999 Chevy Tahoe is located under the dash. It is to the right of the gas pedal.
Follow the below steps to replace the Brake Light Switch on Chevy Blazer:1) Open the Chevy Blazer's driverdoor, and move the driver's seat as far back as it will go. Lean under the dashboard with the flashlight, and shine the light on the brake pedal arm to locate the brake pedal switch.2) Unhook the brake pedal wiring pigtail from the Chevy's brake pedal switch by hand. Unbolt the old brake pedal switch from the mounting bracket using the box wrench set.3) Remove the old brake pedal switch by hand. Insert the replacement brake pedal switch into the brake pedal bracket. Bolt the switch in place with the box wrench set.4) Plug the brake wiring pigtail into the replacement brake pedal switch by hand. Readjust the driver's seat, and close the door. Hope this helps.
Check the brake light switch on the brake pedal