A belt slipping?

I suggest posting your question on Priuschat.com There are many knowledgable Prius owners there.

Thanks for the lead. Happy holidays!

Jem,,, What Belt ???? VBG

A little more detail is in order to discover the source of the sound. What direction is it observed from?
Does the sound occur when the vehicle is cold, or hot? Is there a set of circumstances that make the sound more likely to occur, such as after sitting all night? Or maybe even about five hours AFTER the car has been shut off?

Hi John,

It's hard to know from what direction the sound is coming. I use my Prius to carpool to work every day and my passenger even thinks the sound is coming from different directions on different days.

We've never noticed the sound on the way to work early in the morning and we've only noticed it at the end of a 45 mile commute in the evening, I have to conclude it only happens when the engine is hot.

It probably doesn't matter but I should mention I just had an alignment and new tires installed, which didn't have any effect on the chirping.

The next time it's making the noise, you need to stop, and get out of the car and follow the sound to its source. That's what I would have to do if you brought your car here for me to find the noise. The problem is for me to drive it 45 miles to maybe get it to make the noise we end up with cost issues, that make the practice undesirable.

Laura,

It is the brake actuator. There is a service bulletin out on it, TSB BR001-07. If you do a google search for "Toyota Service Bulletin Prius Brakes" you should be able to find it.

I bought a 2005 Prius a few days ago and noticed the noise last night. It sounds EXACTLY like someone lightly tapping the horn. Other people have referred to it as "barking" instead of "chirping" in some of the threads online. But it sounds like a common problem.

I bought my 05 Prius on the condition that the dealer would fix any issues my mechanic found. In addition to the other things we found, I'm going to have them replace the brake actuator assembly.

Since yours is a 2007 it is probably under warranty as long as your Prius isn't over 36,000 miles.

Good luck!
Sara

Hi sara.

That's a good tip about "that noise", but I have one comment. Without actually hearing the sound and confirming that it is definitely coming from the brake actuator, just running out and changing it could result in disappointment if the sound this particular car is making isn't solved by that service. That's one of the biggest mistakes we see people make, we call them pattern failures when we see a similar reported problem on a number of vehicles. We call it poor diagnostics when a tech simply throws, in this case a brake actuator at a car, without confirming the noise absolutely came from that area this time. I can tell you the brake actuator noise would come from a single specific direction in relation to the driver, and its repeatable, and not random in nature. Lets see how yadax3 responds to this information.

Hi again,

I came back to tell John the noise is coming from under the hood of my car and I just read Sara's post. I have no idea what a brake actuator is but it makes sense from the standpoint it only seems to happen when I'm using my brakes. Is the actuator under the hood?

I'm going to go Google the recall now. My car has over 34K miles so I'd better hurry. Thanks!

Update - I took my car to the dealership where I bought it on Friday and they said they couldn't help me because they were unable to reproduce the noise. They also said the aforementioned service bulletin doesn't apply to my issue because the noise it addresses only occurs when the car is started and is cold whereas my noise happens when the car has been driven a significant distance and is hot. Note: They said they obtained this information when they called Toyota's technical team. The service bulletin doesn't mention this qualifier.

The dealership also said the noise I'm hearing is from the brakes releasing pressure which is a normal function of that type of brakes. They said a triangle with an exclamation point in the center would illuminate of there was a problem with my brakes so I shouldn't worry about the noise.

Do you agree Im concerned about nothing or do you think theyÂre giving me the runaround?

Without first hearing the noise myself, and then working through every step required to understand exactly what the sound is, there is really no way to know if what you can hear is a problem or not.

When mechanical things are doing their jobs, its not beyond reason for there to be some sound associated with fluid movements, solenoids opening and closing, and any other operation of a motor or whatever. It many times can come down to a very subjective judgment whether a given sound, although potentially unpleasant is an indication that there is something wrong. The worst thing any tech could do right now, without complete knowledge of whether this really is a problem or not would actually be to attempt to fix it. If it really isn't a problem, and the sound is in fact normal and the tech does try to fix it, then he/she is going to replace parts that aren't bad, and the noise will still be there. Worse than that, if they try and fix something that isn't really broke three times, especially if it is related to the brakes, then you would in fact fall under the lemon law, because of the three failed attempts to repair.

Keep in mind also that attempting to fix something that actually isn't broke is another way to convince you that there is genuinely something wrong with the car as well. That's not going to be productive for anyone.

I know I have ruffled a few feathers through the years as I take on questions such as yours. You ask if they are giving you the run around. Seriously if they were, what would they have to gain? Techs normally work under a system called flat rate. They are allowed just so many minutes to diagnose a problem, and then each individual repair has "allegedly" been time studied, and the techs pay for replacing a part, such as the brake controller on your car is a fixed amount. Manufacturers are good at having parts like that brake controller returned and if they tear it apart and don't find anything actually wrong with it, they will back flag the dealership, who in turn will take that time back off of the tech. In short this means if they blindly just throw a brake controller at this, not only might the car not be fixed, the tech could actually not be paid for replacing it.

Rest assured no one, not Toyota, the dealer, nor the tech, wish for you to have a problem with the car. If there is a problem they will once identified fix it, but first they have to identify it. With every model there is a learning curve and lets take your car as an example. It could easily be the only car exhibiting a sound as you are describing right now. Many times at the dealer level with cars under two years old, they rely on the fact that the same things happen to the majority of the fleet. That's why the diagnostics can be done in such a short period of time, say 12 to 18 minutes. Then along comes a car that is not playing by the rules, in essence yours, and they don't really have a good way to deal with it and be productive. In fact, if a tech was to take your car, and spend all of the time necessary to figure out precisely whats going on, not only would it be likely he/she would not be paid for the time that they spend. I can show you where techs that actually would make a habit of spending that kind of time eventually lose their jobs because management will sit up in the office and see how many hours the people are turning, and someone will be clocking fewer paid hours, the one that chases all of the ghosts and nightmares!

So to that end, now you see a little deeper inside the dealer, here's how to make their natural weakness not effect your satisfaction with your car. First, they need a set of ears that have positively identified where the sound is coming from. They need to be able to reproduce the sound, almost at will and with a little effort you can accomplish both of these steps. Realize what I am saying, your not doing their job for them, you are empowered to help them solve a possible problem with your car.

The next time your car is making the noise predictably, get them on the phone and let them know your coming in right then, and you expect someone to take a look before the sound goes and hides again. Stay with your car while this step is performed. In all likelihood you know exactly what to do to make the car create the sound, the tech can then move around listening to it to help verify the source. From there all you can do is let them do what they can. You might have to accept that the sound is not an indication that something is wrong, and if this was a "normal" car and not so quiet because the engine isn't running when you are stopped it may easily be drowned out by other typical sounds.

Realize the old adage might just fit here. "If it isn't broke, don't try to fix it".

And from the view of an actual X dealer tech i have had cars in my stall that the customer says has a problem or funny sound. Funny thing is when i get to see it the sound
or problem is not there. I will spend about 10 mins. on it.
If i find nothing i wrte on the work order " no fault found at this time " and send it out. I don't get payed even though i'm clocked in. If the time keepers likes you he will leave you clocked in until you get your next car.
that gives you a heads up on your next payed hour. Remember
we use " trimmers " for all electrical, A.C., interiors,
and everything the mechanics and body shops don't fix. That
includes water leaks and wind rushes and roars. Everything
is straight time. If you are very good friends with the time keeper he will clock you in even before the car jocky
brings you your next car. If you are good you make a lot of
money. We have to bring in 75 percent of our stall to keep
our job. Most of the realy good techs. have no problem
bringing in 100 to 150 percent of the stall. Usually the
tuneup man and transmission man can bring in 200 percent, no problem.