it is hissing because there is a vacume leak in the brake booster it will require a new brake booster
Sounds like the power brake booster is bad. Get it checked out.
I'd check for faulty Brake booster. I've seen cases of them cracking. I'm pretty sure their all made of plastic, the falcon boosters.
it is located to the right of the brake pedal
To reset the neutral gear on a Ford Falcon, first ensure the vehicle is in a safe, level position. Turn the ignition to the "ON" position without starting the engine. Then, press the brake pedal and shift the transmission into the "Neutral" position. Finally, hold the brake pedal for a few seconds before shifting back to "Park" or "Drive." If issues persist, consult the owner’s manual or a professional mechanic for further assistance.
Adjust the brake switch which is above the brake pedal.
brake light switch is above the brake pedal
on the break pedal itself if you look under th edash youll note a plug going onto it that's the switch / sensor
brake pedal light switch.
On the brake pedal arm.
Regular DOT3 brake fluid
To change the brake light switch on a Ford Falcon ED, first disconnect the negative battery terminal to ensure safety. Locate the brake light switch, which is typically mounted on the brake pedal assembly. Remove the wiring harness connected to the switch, then unbolt or unclip the old switch from its mounting. Install the new switch by securing it in place, reconnecting the wiring harness, and finally reconnect the battery to test the brake lights.
Just above the brake pedal on the pedal shaft.