New Disturbing Noise

Jim.Biggs · 12-20-2007, 09:49 PM

A little help diagnosing this would be appreciated.
This is NOT a joke! I have owned the car since NEW and it now has 119,000 miles on it. So I am quite familiar with noises the car routinely makes...

This started about a week ago... I did not think the noise was coming from the Prius ... but now it is confirmed.

I have only noticed the noise when the engine is off. For instance, pressing the power button to start, leaving the car in Park and a few seconds before the engine starts (not every time mind you) a noise lasting about 1/2 of one second. It is LOUD and sort of a "BHONK". I have also heard this noise setting at a red light. It is VERY loud. It is loud enough that others think I am Honking at them and they will honk back!

Here is more to go on... I have found a way to recreate it all most every time. (Nothing is perfect)

Here we go:
With the car fully warmed up after driving around for say 15 minutes, slow down and stop in such a manor that the engine is off. While watching the Energy Display make sure the engine is off and adjust the brake pressure so that the battery remains supplying power to the MG's. The noise will NOT occur at this point. I have waited a full FIVE minutes and the noise did NOT occur!

NOW, for the noise... Press the brake firmly. The Energy Display will show that the battery is no longer supplying power to the MG's. About 5 seconds later "The sound".

Someone that has a flow chart or understands the various functionalities SHOULD be able to tell me what cycles at this point!

I know this is not much to go on but it is so fast and intermittent that it is difficult to isolate. I thought at first the horn was intermittently beeping due to a computer or electrical failure but the sound is wrong. The noise is a little lower frequency than the horn. Perhaps a pump is trying to start and the impeller rubs the casing occasionally...

BTW, the temperature when this happens is mid 40's to low 60's F.

Thanks in advance!

SureValla · 12-20-2007, 09:54 PM

perhaps your talking about the sea lion infestation?

see this thread, complete description and solution in my post on page 5.

N3FOL · 12-20-2007, 10:40 PM

Interesting phenomena

I'll have to keep an ear out and start listening for that 'barking' sound.

firepa63 · 12-21-2007, 10:50 AM

I've had my Prius for about 4 years and I'm always "hearing a new sound", or so I think. As long as I have no warning lights and the car feels right to me, I just turn up the radio and go along my merry way. The same thing has happened with every car I've ever owned. Sometimes it turns out to be mind over matter. My thoughts...

N3FOL · 12-22-2007, 05:45 PM

On my '08, after turning the power off I can hear a buzzing noise under the hood. I suspect it is the Hybrid system that is 'doing its thing'.

Yes, the car runs great and I am still in the break-in period...closing 2K.

Jim.Biggs · 12-30-2007, 03:41 PM

A followup...
Perhaps it WAS an ABS component "barking" but like several other problems I have had... I post the issue here and like magic the problem goes away! It has been gone about a week now! I did nothing to it.

I love these self repairing cars!

donee · 12-30-2007, 04:37 PM

Hi Jim...,

Is there any consistancy in speed when the BHONK happens? Like 7 mph ? That is the speed the regeneration kicks out and the hydraulics actuate the fricting brakes. If so, that would imply the BHONK is the brakes taking up the wear clearance (which would need to be huge) when the Hydraulics press the pads to the caliper, or the calipers are binding.

If that is the case, then a caliper cleaning is in order. Look for the caliper binding mechanisms, or that if the guides and guide bushings (if the Prius has those?) are not worn or nicked. Properly lubricate the caliper guides Hobbit has a write-up on caliper maintenance on his web site.

jamesbalch · 01-06-2008, 09:53 AM

I have this EXACT same noise, only it is a little softer. Sounds just like someone lightly bouncing thier fist on the horn to remind someone in front of them that the light has turned green and to get going!

There is a service bulletin in regards to this brake noise....they call it a "squeak" but I think this is the noise they are reffering to.

See the TSB section at the top of the page and look up "Brake Noise" (TSB BR001-07).

When I was in for a routine inspection, I mentioned this soft "honking" noise to the service department.....they lubed the brake pedal linkage. Of course it is still there. I wil have them bleed the brakes next....then replace the ABS brake actuator assembly under warranty if neccesary.

Rather aggravating little noise, isn't it?BR001-07

12-20-2007, 09:49 PM	#1
Jim.Biggs Zardoz Join Date: Oct 2006 Location: Scottsdale, AZ Posts: 22 My Car: 2005 Prius Model: Package: #7 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	New Disturbing Noise A little help diagnosing this would be appreciated. This is NOT a joke! I have owned the car since NEW and it now has 119,000 miles on it. So I am quite familiar with noises the car routinely makes... This started about a week ago... I did not think the noise was coming from the Prius ... but now it is confirmed. I have only noticed the noise when the engine is off. For instance, pressing the power button to start, leaving the car in Park and a few seconds before the engine starts (not every time mind you) a noise lasting about 1/2 of one second. It is LOUD and sort of a "BHONK". I have also heard this noise setting at a red light. It is VERY loud. It is loud enough that others think I am Honking at them and they will honk back! Here is more to go on... I have found a way to recreate it all most every time. (Nothing is perfect) Here we go: With the car fully warmed up after driving around for say 15 minutes, slow down and stop in such a manor that the engine is off. While watching the Energy Display make sure the engine is off and adjust the brake pressure so that the battery remains supplying power to the MG's. The noise will NOT occur at this point. I have waited a full FIVE minutes and the noise did NOT occur! NOW, for the noise... Press the brake firmly. The Energy Display will show that the battery is no longer supplying power to the MG's. About 5 seconds later "The sound". Someone that has a flow chart or understands the various functionalities SHOULD be able to tell me what cycles at this point! I know this is not much to go on but it is so fast and intermittent that it is difficult to isolate. I thought at first the horn was intermittently beeping due to a computer or electrical failure but the sound is wrong. The noise is a little lower frequency than the horn. Perhaps a pump is trying to start and the impeller rubs the casing occasionally... BTW, the temperature when this happens is mid 40's to low 60's F. Thanks in advance! Last edited by Jim.Biggs; 12-23-2007 at 10:58 AM. Reason: More details to aid troubleshooting

12-20-2007, 09:54 PM	#2
SureValla Senior Member Join Date: Jul 2007 Location: White Plains, NY Posts: 505 My Car: 2007 Prius Model: Package: #3 Thanks: 17 Thanked 9 Times in 7 Posts Friends: 0	Re: New Disturbing Noise perhaps your talking about the sea lion infestation? see this thread, complete description and solution in my post on page 5.

12-20-2007, 10:40 PM	#3
N3FOL Senior Member Join Date: Dec 2007 Location: Stewartstown, PA. Posts: 791 My Car: 2008 Prius Model: Package: #4 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Re: New Disturbing Noise Interesting phenomena I'll have to keep an ear out and start listening for that 'barking' sound.

12-21-2007, 10:50 AM	#4
firepa63 Senior Citizen Join Date: Jul 2005 Location: SE Pennsylvania Posts: 930 My Car: 2009 Prius Model: Package: #5 Thanks: 0 Thanked 43 Times in 39 Posts Friends: 0	Re: New Disturbing Noise I've had my Prius for about 4 years and I'm always "hearing a new sound", or so I think. As long as I have no warning lights and the car feels right to me, I just turn up the radio and go along my merry way. The same thing has happened with every car I've ever owned. Sometimes it turns out to be mind over matter. My thoughts...

12-22-2007, 05:45 PM	#5
N3FOL Senior Member Join Date: Dec 2007 Location: Stewartstown, PA. Posts: 791 My Car: 2008 Prius Model: Package: #4 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Re: New Disturbing Noise On my '08, after turning the power off I can hear a buzzing noise under the hood. I suspect it is the Hybrid system that is 'doing its thing'. Yes, the car runs great and I am still in the break-in period...closing 2K.

12-30-2007, 03:41 PM	#6
Jim.Biggs Zardoz Join Date: Oct 2006 Location: Scottsdale, AZ Posts: 22 My Car: 2005 Prius Model: Package: #7 Thanks: 0 Thanked 0 Times in 0 Posts Friends: 0	Re: New Disturbing Noise A followup... Perhaps it WAS an ABS component "barking" but like several other problems I have had... I post the issue here and like magic the problem goes away! It has been gone about a week now! I did nothing to it. I love these self repairing cars!

12-30-2007, 04:37 PM	#7
donee Senior Member Join Date: Aug 2005 Location: Chicagoland Posts: 2,244 My Car: 2006 Prius Model: Package: #2 Thanks: 2 Thanked 54 Times in 47 Posts Friends: 0	Re: New Disturbing Noise Hi Jim..., Is there any consistancy in speed when the BHONK happens? Like 7 mph ? That is the speed the regeneration kicks out and the hydraulics actuate the fricting brakes. If so, that would imply the BHONK is the brakes taking up the wear clearance (which would need to be huge) when the Hydraulics press the pads to the caliper, or the calipers are binding. If that is the case, then a caliper cleaning is in order. Look for the caliper binding mechanisms, or that if the guides and guide bushings (if the Prius has those?) are not worn or nicked. Properly lubricate the caliper guides Hobbit has a write-up on caliper maintenance on his web site.

01-06-2008, 09:53 AM	#8
jamesbalch Member Join Date: Oct 2006 Location: Northeast Posts: 69 My Car: 2006 Prius Model: Package: #6 Thanks: 0 Thanked 2 Times in 2 Posts Friends: 0	Re: New Disturbing Noise I have this EXACT same noise, only it is a little softer. Sounds just like someone lightly bouncing thier fist on the horn to remind someone in front of them that the light has turned green and to get going! There is a service bulletin in regards to this brake noise....they call it a "squeak" but I think this is the noise they are reffering to. See the TSB section at the top of the page and look up "Brake Noise" (TSB BR001-07). When I was in for a routine inspection, I mentioned this soft "honking" noise to the service department.....they lubed the brake pedal linkage. Of course it is still there. I wil have them bleed the brakes next....then replace the ABS brake actuator assembly under warranty if neccesary. Rather aggravating little noise, isn't it?BR001-07 Last edited by jamesbalch; 01-06-2008 at 09:54 AM. Reason: Misspelled Word