What is that high pitch squealing/whining noise?

03 Tacoma 4x4. Help?! Pressed the brake pedal and heard a high pitch squealing/whining noise coming from the engine area while pressing on the brake pedal. Noise stops when brake pedal is released.

 

Are you sure it's not coming from the brakes themselves? Usually when you hear squealing while braking it's because the pads are getting low and need to be changed, or you have dirt/rock/road grime stuck between pad and the rotor causing it to squeal when you brake.

Brake pads have a little metal piece built into them so that they intentionally squeal when getting low to let you know that they need to be replaced.

 

I don't know what a failing brake booster sounds like but it might be suspect, being that the noise is only while you have pedal pressed down

 

Does it only happen when your GF is riding with you?

 

Are you saying the squealing happens when youre completely stopped by the car is running?

 

If it's only happening when you're pressing on the brakes (and still moving), it's very likely your front brake pads are just worn out and need to be replaced.

When the brake pads wear down, eventually a piece of metal is exposed that makes a horrible sound when pressing the brakes.