Aptosuser

My 2010 RX 450h makes an odd noise when I accelerate and when I brake; not all the time, but often enough to make me wonder what if anything is going on. This noise sounds most like a quick, light beep of a car horn, as if another driver just barely touched the steering wheel, and for a time I thought some impatient motorist was beeping at me. Then I realized that the sound was coming from my car. Sometimes, it seems to come from the front and sometimes from the back. If the Lexus dealership were closer, I'd take the car in and ask about this, but it's 40 miles away, so before I get all worked up about this I'd like to know if anybody here has heard a sound like this in their car and whether they have any idea what it is. Again, I hear it when I accelerate and when I brake but not other times. The car has 20,000 miles on it now and is under warranty because it's CPO.

VVRX

Check and make sure that your hood is not unlatched.

Aptosuser

It didn't look or feel unlatched, but if it was, it isn't now.

Aptosuser

Update: The funny sound is coming more often -- essentially almost any time I brake in any manner more than gradually, and often when I accelerate after a full stop, and that's with gentle acceleration. It seems like it's coming from under the car, and most often sounds like it's in the front somewhere. Now that it seems to be happening regularly, I guess I'll have to drive the 40 miles to the dealership so that they can hear it. I called to ask about it, but the service adviser didn't know what it could be, guessing only that maybe the noise was from the windshield-washing-fluid reservoir being low. Anybody have any thoughts about this mystery?

corradoMR2

The only time my hybrids RXh and CT made funny noises that sounded like a buzzing horn was after the car was parked and turned off. It also states in the manual that these noises are normal but I don't recall if there was a mention of this while the vehicle is in motion. Do you know if these noises while in motion are similar to what you hear while parked?

Cruiter

I've got a 2010h with near 60K now and can't figure out a noise you may be experiencing. Keep up updated after visiting the dealer please.

Aptosuser

I took the car in to the dealer (40 miles away) yesterday, and of course, the car would not make the funny sound when a technician when for a ride-along with me. Figures.

corradoMR2

^^^ Sorry to hear, I know the feeling. If possible, take a video clip of the noise before the next attempt.

As a matter of fact, if you can post it on Youtube and link it here, we can also get to see/hear it and make a more objective comment on what it can be.

Aptosuser

It happens after I've been driving at residential-street speeds for awhile, when I brake and when I accelerate away from lights or stop signs (starting from 0 mph). I'm guessing this has something to do with the left-front brake, but why would it happen when I step on the accelerator? Is a brake shoe catching somehow? Is there something going on with the regenerative braking? I'll have to try to duplicate it at the dealer. I recorded the sound on my smartphone, but mp4 files can't be uploaded here.

Aptosuser

Yesterday I took my RX450h to an excellent independent shop (recommended by a relative and highly praised on Yelp!) to see if they could figure out the source of the clicking noise which they agreed was coming from the left-front wheel -- on braking and accelerating. They took the tire off and inspected the calipers, brake pads and so forth but couldn't find anything wrong with the car, just as the Lexus dealer in Monterey hadn't been able to find anything amiss. So today, I resorted to "the Google" again. I found a post by an owner of an IS300 (in S. California) who had been wrestling with a similar clicking noise from the rear driver's-side wheel also on braking and accelerating. He took his car to an independent mechanic who found the problem: a loose rear-axle nut on the driver's side. I checked the IS300's specs; it's a rear-wheel drive car, so that makes sense. My RX450h relies on front-wheel drive (when it's not in AWD, which is essentially never). So it could be that the source of the clicking noise in my car could be a loose driver's side front-wheel axle nut. I'll take the car back to Monterey and ask the dealer to check into this. They didn't charge me anything when they checked it out but couldn't find anything a week or so ago. For anyone who's interested, the IS300 owner's forum post follows:

IMPORTANT FOR IS300 Owners> Finally Found Clicking Noise from Drivers Side Rear Wheel
Well I'll try and keep it simple...

For the past approx 1.5 years, I have a had an annoying yet bearable CLICKING noise coming from my rear Drivers side wheel..

No - it's not the rear or front brake pads shifting.
But it sounds very similiar.

First of course thought it was the old brakes or brake components... nope...(just got new ones), maybe my old wheels.. nope...(just got new ones), maybe the hand brake... nope (adjusted)... etc...

The noise was pretty consitent, but yet from time to time it would go away... It would happen whenever a load was placed on the rear wheels.. Accelerating, Decelarating, backing up into a spot or leaving the spot... stop and go traffic... etc...
This was even after I had a reputable shop, check it out... about a year ago...

Finally it came back again 3 months ago... I had enough!!!

This weekend I took it to Dynamic Auto Service here in So Cal...
The Lexus Certified Master Tech (which I know for a long time), found the problem in about 10 minutes...


I couldn't beleive it..
I had a Loose Rear Axle Nut on the Drivers side.

It was maybe 3/4 or 1 full turn out of place. This is the nut that has the cover on it and a cotter pin to prevent it from backing out.
It is located in the center of the rear wheel hub and the nut is deep in the axle ending. It holds the rear axle in the center of the hub.

No Need to Remove Rear Rotor or Rear Caliper to see if this is your issue..
You just have pull the rear wheel off...

Well I guess after 5 1/2 years and 94K Miles, it found a way to back out of place. I never had any work done on the axle.
He removed it and re-installed it.
We can see a clean spot on the end of the axle thread were the nut installs.

My friend/tech figured it was never installed correctly during build/production and it finally got loose enough to allow the rear axle to CLICK or SHIFT on take offs, etc..

Pretty weird if you ask me.. But the noise is finally gone!!!
From a safety stand point I feel a lot better that the problem was found a fixed!!

vlad_a

I highly doubt your problem is the same as the IS300 issue above. On the rear of the driver side, the locking washer was a little loose. It could have made the same noises, as described above. The nut itself was very tight. We ended up securing the washer by bending out the pin that came through it. The only reason I was looking at it was of the same post above. But, that's on my IS300!

What is more common on Toyota vehicles is the sliding pin seizing up on front calipers. That is usually accelerated by salt in the snow regions. That made some really weird clicking noises. I replaced both front calipers. Again, this is on my IS300. Keep in mind, it was already 10 years old at the time.

Aptosuser

vlad_a, I took my RX450h back to the Monterey dealer this past week and asked them to check the left-front axle nut. Though the service adviser said the design of the axle nut in the RX is not the same as in the IS, the sound I heard was the same as that reported by the IS owner -- a single click on braking and/or acceleration, and not a continuous clicking noise. So it seemed reasonable to me that source of the noise was the same, and I insisted that they check it. I Their mechanic did after driving the car and verifying the clicking sound for himself. He tightened the nut by a "millimeter", drove the car again and reported that the sound was gone. Knock (or click) on wood, I haven't heard it since. So it seems the problem has been solved. t didn't take them very long and they didn't charge me for it.

Cruiter

Something about your original post was ringing an old bell. I finally remembered, when I got my RX 450h in June of 09, I was getting the very same sound. The dealer heard it but couldn't fix it as it was erratic. I couldn't hear it with the windows up and the radio on so gave up on it. But later when I started using Toyota for service I brought it up the 1st time I was there by asking them to make sure they tightened the half shaft bolts as called for in the manual. No problem, the Toyota required the same thing. They did and the click was eliminated. So from day one, one of the bolts was not tight.

Aptosuser

Jim,
What's a half shaft and where is it?
Steve

Cruiter

Drives the front wheels from the tranny.