2003 Toyota Sequoia

Brakes problem
2003 Toyota Sequoia V8 Two Wheel Drive Automatic 140000 miles

There is a high pitched whistling sound coming from where the brake pedal goes thru the firewall. Does not occur when brakes are applied even slightly or when under acceleration and is louder if brake pedal is pulled back with your hand. Doesn't happen if the engine is cold and only starts after about 10 miles. Brakes work fine otherwise, no hard or soft pedal. I have been told it must be the brake booster but I think there may be a vacuum leak elsewhere. What do you think. Thanks
July 21, 2009.

I am experiencing the same problem with my 2002 Toyota Sequoia, V8 4 wheel drive automatic with 160000 miles. However the noise can be heard outside the vehicle. Curious about what the problem may be. Thanks.

Apr 11, 2011.
My dealer says it is the brake booster. Another forum mentioned a crankcase valve located under the manifold exhaust. I am unsure what that is.

Jul 25, 2012.