strange brake noise maybe under dash

[edwardh1]

2004 toy highlander
I sometimes get a strange noise under the dash- it mostlry happens when letting up on the pedal. especially when moving from a stop. the noise is a woomp noise over about 1 or 2 second as you raise your foot. it makes the noise at the start of the travel of the pedal rise only.
It does it mostly
- not when cold or first driven, works fine then
- when hot or when outside weather is hot it does it more it seem.
At the same time I get this noise the pedal seems lower and it seems the car wants to creep forward, like a bad master cylinder.
I took this problem to the dealer last year and they could never hear the noise or experience the creeping. they said all highlanders had "soft pedals" the only thing that would cause a low pedal they said was bad master cyl which they changed (expensive) did not cure it.
have there been any linkage recalls in the pedal that might cause binding or noise? would adjustment of what I think is the stoplight switch have any effect or cause lack of full pedal return and cause this condition? ?
what looks like my stop light switch (has a green plastic part that pushes on the pedal). should there be free play between the switch and the pedal?
this car had the brake piston "cup: recall, but that was on the first master cylinder.
Could power brake booster cause this, or could the cup problem have leaked fluid into the booster?

 

[CT8]

"I know women who are always late, they do not allow travel time, they think like Star trek, you leave one place and materialize somewhere else." 1971 my first year in college. I had a 1971 Kawasaki Mach III in its day the fastest motorcycle on the road. I remember my first class was at 8 am. I would drive 125 mph as indicated on the speedometer from the time I entered the freeway to the off ramp to the college, I was always late for the first period class.A bit of wisdom.

 

[eljefino]

It's your vacuum booster making the noise. It's because you have a soft pedal with lots of travel. I have a "not fantastic" pedal in my camry which shares a lot of parts with your Highlander and it's generally regarded to be "that way".

I've seen other clunkers with soft brakes and they make the vacuum booster swish, too.

But since yours just started, it hasn't always been this way, and it's worth further investigating. Focus on improving the soft pedal and the noise will lessen.

 

[Kuato]

Originally Posted By: eljefino
It's your vacuum booster making the noise. It's because you have a soft pedal with lots of travel. I have a "not fantastic" pedal in my camry which shares a lot of parts with your Highlander and it's generally regarded to be "that way".

I've seen other clunkers with soft brakes and they make the vacuum booster swish, too.

But since yours just started, it hasn't always been this way, and it's worth further investigating. Focus on improving the soft pedal and the noise will lessen.


Agree - since the noise is new then there's something that has changed. I'd be checking fluid levels, any vacuum hooked up the the unit, and being observant of any change in braking performance.






Originally Posted By: CT8

"I know women who are always late, they do not allow travel time, they think like Star trek, you leave one place and materialize somewhere else." 1971 my first year in college. I had a 1971 Kawasaki Mach III in its day the fastest motorcycle on the road. I remember my first class was at 8 am. I would drive 125 mph as indicated on the speedometer from the time I entered the freeway to the off ramp to the college, I was always late for the first period class.A bit of wisdom.


Dude, lay off the hash pipe it's only Thursday.

 

[Superflop]

I would also like to agree with the other guys. Reading your post made me immediately think of a brake booster issue. Please have it looked at. I thought this before seeing the other posts.