Brake “hiccup†sound.

I think I've had the same thing happen... Hadn't thought to ascribe a biological function to it, though...

I live near sea level, but every time I visit my family in the high Cascade desert (high elevation and colder), the brake system or brake pedal makes a vibration noise when I depress the pedal. The sound is similar to rubbing an inflated latex balloon.

Absolutely no idea what is causing this, but I would also like to know. The service center was not able to get my brakes to "hiccup" - perhaps the rather savage-looking technician scared the hiccups away.

Anyone else?

 

We just went to Reno-Truckee from Sacramento and noticed the same noise as I released the brake from a dead stop. Temp was 34F and we were sitting for 3 hours in stop & go traffic. Back at Sacramento there was no noise.

 

Hi -

Thought I was imagining things but I also have started to hear this noise after driving in hot conditions and heavy traffic - I do not hear it all of the time but it does seem related to the brakes.

Let me know if you find a solution.

Thank you.

ML

 

First - I do not know - I've never heard a Prius do the hiccup thing - so this is at best an educated guess...here goes.

Any Toyota with B/A (brake assist) including the Prius has an accumulator with pressurized brake fluid. In the event you are in a panic stop and did not use enough force on the pedal to induce ABS operation, the store of pressurized fluid will be released into the brake system to induce ABS and thusly bring the vehicle to a shorter and more stable stop.

As you drive - (and it sounds like heat in the brake system - which relates to heat in the brake fluid) - pressure can change in the BA accumulator - if heat increases, pressure increases, and the system will bleed off some pressure to return the sytem to a proper level. Is it possible you are hearing this pressure bleed during these events? - Just a theory ... Food for thought...

 

Not for me. The sounds occurs when the vehicle is cold, and seems to go away after driving for 20 minutes or so. Cold and high altitude are the only two significant possible contributing factors in my case, although neither may be responsible.

My situation (and this has happened on three occassions) is this: drive from the Oregon valley to Central Oregon in the winter. Park overnight. Starting with the next morning, the brakes will make a strange noise any time I drive my Prius in that area. Problem goes away upon returning to the soggy, warmer valley.

The sound itself is much akin to rubbing an inflated latex ballon, and occurs when lightly depressing the brake pedal. The sound is not well correlated with the physical pedal displacement, but seems to be generated by an automated part of the brake system.

My evidence for this statement is that the sound is highly stereotyped - it sounds the same regardless of how slowly, quickly, delicately, or forcefully I depress the brake pedal.

Any ideas??

 

Thanks, Rick. Glad to know that I'm not alone.

I'll give Toyota a call and report this as well. Better safe than sorry if it turns out to be a defect.