Excessive Regenerative Braking Noise?

[susapix]

I just took delivery of a silver RX400h yesterday. I test drove the model in Colorado a couple of months ago and loved it. But the particular car I ended up with turns out to have a very noticeable and annoying high pitched whine whenever the regenerative braking kicks in.

I'm wondering what experience other drivers have had. Is my noise abnormally loud or is it normal? Can it be tuned down in the shop? Does it get better as the car gets driven? Or do you just have to get used to it?

I certainly don't remember anything like it on the car I drove in Colorado. There may have been a soft whirr, but nothing like this.

The two standard complaints about the RX400h seem to be that it doesn't get the EPA gas mileage (but no car ever does) and that the brakes can get weird if you hit a bump while using them. But so far I've not seen compaints on this forum about the car whining. Which is odd. Nobody likes to hear whining.

Yes, I know I'm whining right now.

Did I get a lemon?

[sakumar]

I just took delivery of a silver RX400h yesterday. I test drove the model in Colorado a couple of months ago and loved it. But the particular car I ended up with turns out to have a very noticeable and annoying high pitched whine whenever the regenerative braking kicks in.

I'm wondering what experience other drivers have had. Is my noise abnormally loud or is it normal? Can it be tuned down in the shop? Does it get better as the car gets driven? Or do you just have to get used to it?

I got mine last month and it does the same thing. The whine sounds (to me) like a police siren in the distance. The manual states numerous times that the brakes make an unusual sound so I guess that is the way it is supposed to be. I must say that after driving around a bit, and with the music on, it is not as disconcerting as it first was. I don't think it is less loud, just that I am getting used to it.

[Rx330driver]

you know, if anything, it should go away. no car, especially lexus should get that sound. IF it doesnt go away by your 500 mile free service, or is it a 1000, i would tell them to get it fixed or something. It might be the brake pads?

[RX400h]

Your gas mileage will creep up over time. Ours went from an average of 21 to an average of 25 over a period of approx. 5000 miles worth of driving.

Although I haven't noticed a high-pitched sound when braking, I really like the jet turbine-sound that emanates from under the hood sometimes.

[atebit]

I haven't noticed the whine, but maybe my radio's too loud to notice.

I do, however, have the bad braking over a bump thing. That will get addressed at my first service, which BTW I'm told is now at 5,000 miles. So much for the "tighten the bolts" freebie service.

[jerryray]

My 400h is just 1 year old with 14,000 miles. I don't hear any noise from the braking system. I do drive with the windows up most of the time.

Is the noise from inside or outside the car?

[sakumar]

My 400h is just 1 year old with 14,000 miles. I don't hear any noise from the braking system. I do drive with the windows up most of the time.

Is the noise from inside or outside the car?

It's not from inside the cabin. It is a whine from the Electric motor/generator when it is engaged during regenerative braking. It is more pronounced when on a down-slope and I am coming to a dead stop (say) at a stop sign. It is not a screech that is typically heard when the brake pads are worn out.

Perhaps the Original Poster had a different observation but the description was similar to what I had noticed in my one month old RX400h. Also, if the radio/cd is on then the whine is not that noticable.

[sakumar]

On Page 10, and again on Page 411, the manual states:

When applying brakes, you may hear a sound coming from the regenerative brakes. However, this does not indicate any trouble.

The sound is noticable, but I assumed it is normal. Now I think I am going to seek out another 400h owner (I have seen another one in the parking lot at work) or have it checked out by the dealer.

[susapix]

Sounds like Sakumar and I have the same experience. But most others do not. Perhaps it varies from vehicle to vehicle and we both ended up with noisy ones.

The odd thing is that my husband, who drives a BMW, doesn't find the whine bothersome at all. He feels it is useful feedback that the regenerative system is working and it makes him feel virtuous.

Yes, I know that the owner's manual says that noise from the brakes is not indicative of a problem. But they are talking about a mechanical problem. I don't think the car has a mechanical problem I just think the sound is unpleasant. Otherwise I love the car.

So I guess I'll drive it for a while and see if the noise gets fainter (or that I get used to it). If not I'll bring it up at my first service and see if there are any adjustments that can be made.

[katzjamr]

my 400h is one year old with 13,000 miles. i sometimes drive with no radio or cooling fans when im talking on the phone. this whine you describe is normal. toyota was worried that thier hybrid would sound like an oversized golf cart so they packed in extra sound insulation all around the cabin and used a laminated windshield to make it as quiet as possible. there is a good chance this sound was there on the models you test drove however it is impossible to anticipate every sound a hybrid will make during one test drive,. ( one reason i took four test drives on three vehicles) it is one of the trade offs you make when you purchase this otherwise excellent system. you will get used to it, it wont 'go away' and you can crank up the mark levinson if its really that bothersome.

[jerryray]

The sound you guys hear , is that the whineing as you slow down>

It may be the normal sound of the CVT transmission gearing(slowing) down.

There are two large flywheels spinning in there, if you ever accelerate hard and take toy foot off the gas you eill hear them too.

[skyfish400h]

The sound you guys hear , is that the whineing as you slow down>

It may be the normal sound of the CVT transmission gearing(slowing) down.

There are two large flywheels spinning in there, if you ever accelerate hard and take toy foot off the gas you eill hear them too.

My Lexus has the "whine" noise. I notice it both accelerating and decelerating when the the electrics are working. I agree that it could be the CVT, but for me it seems more tied to the the electic motor operation in both modes and is especiallaly noticable as you come to a stop.

It's not real loud but I've had newbies in the car notice the sound and ask about it. If anything I'd have to say the sound has gotten louder as miles add on, but maybe it because now that I'm tuned into the frequency, its harder to ignore.

[sakumar]

The sound you guys hear , is that the whineing as you slow down>

It may be the normal sound of the CVT transmission gearing(slowing) down.

T

The excessive whine that I notice is when I step lightly on the brakes. I do hear the softer whine of the motor when accelerating, but that is not as loud as the regenerative braking noise.

Neither is this louder whine present when I am coasting (i.e. foot off the accelerator, but not on the brake). In this case too, the motor is acting as a generator but it is not as noisy.

I am speculating here, but during regenerative braking, the system must be engaging some additinal gearing which has the affect of (a) more rotations to the electric generator/motor as compared to coasting and (/B) slowing down the vehicle. Perhaps it is the additional gearing, or maybe it is the higher rpm of the generator that is responsible for the whine during braking?