RudeDoggy

I have a new-to-me 2018 RX450hL and I've noticed the knocking sound when depressing the brake pedal. I didn't notice the sound when test driving it a couple of months ago. I can recreate the sound as posted by pdaeng at will.

I just wanted to mention that my RX is built in Japan but still exhibits this issue it seems, so it's not just the Canada built RXes that are having these issues.

Hopefully there is a Canadian TSB outlining the fix for this seemingly known problem as the closest dealership is 3 hours away.

maureenBH

MY 2019 rx450H f-sport started the chirping sound 6 months after I bought it. I brought it to Lexus and they said there was nothing wrong. So the chirping sound got worse by December- a few months later and this time I dropped it off at Lexus and said adamantly “I’m not picking it up until it’s fixed”. They finally fixed it but it took them a week to figure out what was wrong with it. Then the service guy tells me that nobody wanted to fix it because it was too expensive. I don’t think he was supposed to tell me this.

vettestr

Hi, did he tell you what was the problem? My wife 2017 got the same chirping sound. They fixed it but the chirping sound still there. It doesn't happen every time.
Thank you!
-Mike

ClownLoach

So this problem even affects 2021 RXh models - I am having the same issue.
Took it to the dealer today (I have a trustworthy service advisor who is always transparent and doesn't BS me) - he stated that there is a revised brake actuator part and new TSIB on the way - that it was expected in February but has been taking a while due to the pandemic.

golferjack

Did you ever get the new TSB info and the part number?

mckdaddy

Yes! I took mine in last week for an oil change and they mentioned the TSB brake actuator thing to me and asked if I’d been having any brake noise since buying it (got a 2020 450h in May 2020) and I responded that I’ve had the noise since day 1. It is now quiet to press the brake pedal, and seems wonderfully strange to be that way.

golferjack

Was it a different TSB and part number?

mckdaddy

I do not know anything other than he mentioned “TSB” and “brake actuator”, and I was gleeful to have the noise no longer occur.

Wiener

I have got a problem with my new 2020 Japan-made RX450h. It has got like 17 000km and since its first service (15 000km) it has developed a strange behavior. After depressing the brake pedal quite firmly and having it depressed for like a second or two, there is a loud knock/grind coming from after the hood, it is noticable on the brake pedal too. I have not only experienced it while the vehicle was stopped but also while driving and needing to brake firmly. It has shown itself first when I was changing from reverse to drive - that is the situation when you usually depress the brakes firmly and leave it that way for a second or two.

It is loud, comes from the actuator assembly (this angular silver-colored part visible on the video with the Toyota 44050-48320 label on it) and can be felt even on the brake pedal. Under the hood in can be felt on the actuator itself, on the reservoir and on the hose between those two. However, it is intermittent. On some days I can recreate the knock every time I depress the pedal. On the others like today I can't recreate it even once during a 1h drive.

There is also buzzing coming from the can-shaped part with the NOK MZ21-135A label on it. The knock is not felt on that part.

Any ideas?

The dealership says that it is a known problem - a brake pump cavitation, which is a known design problem and they are waiting for Lexus to fix it. I even took a mechanician (not the service advisor) on a ride and he heard the noise and was absolutely sure that it is the brake pump cavitation. They told that it is a common thing on the Lexus NX. I don't believe them much. I would have noticed it before the first service for sure. And they obviously did not redesign the pump at the service...

They do clean the brakes at the service so my theory is air trapped in the brake system. But I don't have enough technical knowledge to back it up somehow. Oh and the video!
You can hear the noise in: 0:15, 0:36, 0:44, 1:21.
https://streamable.com/lr5ff0

This sounds kinda different to your recordings guys.

golferjack

"The dealership says that it is a known problem - a brake pump cavitation, which is a known design problem and they are waiting for Lexus to fix it. I even took a mechanician (not the service advisor) on a ride and he heard the noise and was absolutely sure that it is the brake pump cavitation. They told that it is a common thing on the Lexus NX. I don't believe them much. I would have noticed it before the first service for sure. And they obviously did not redesign the pump at the service..."

We have a 2016 RAV and it has the same sound, but only when I open the driver door, Opening the door on the Rav, begins the process of getting the car ready to drive. The brakes do not have a vacum air supply, so the car is getting the brakes ready by running a motor to provide braking power. The RX does not go through the activation process until the system is on. The sound you hear is discussed on the RAV forum and from what I have found is completely normal, and does not have anything to do with bleading brakes. We have had the sound since day one and our braking system is just fine.

Wiener

No, I do not mean the buzzing, the buzzing is fine. You can hear a knock/thump/pop in 0:15, 0:36, 0:44, 1:21. Or do you mean that the knock/thump/pop is normal? It happens not only on startup, but also when stopped on the red lights after a 1 hour drive for example or even while driving on a highway and braking firmly in movement. I just created the video in my garage so you can hear it better. It would obviously not bother me if it was only on system startup.

golferjack

I meant the buzzing

Wiener

I've got another video for you. Now with an accelerometer placed on the actuator so that you can not only hear the sound but also see the vibration. And again, it is NOT about the buzzing.

You can hear the noise isolated in 0:21-0:23 for example.
https://streamable.com/r5fu27

SoCalRX

Good luck in getting matters resolved. Trying to resolve our brake issues was a nightmare on our 450h, and we are simply waiting to until our same problem starts again. We are on our fourth ABS unit and ancillary components, plus weeks without our RX (they did provide a loaner throughout each ordeal). Likely this is our first and last Lexus vehicle. We do like the salesperson who sold us the vehicle and the service advisor we deal with, but that is about it. Dealing with Lexus directly is a mixed bag. The Lexus Techs that work at our dealership are also a mixed bag of competency.

Wiener

So I've got some feedback. I have visited the dealership again and they did some more diagnostics and documentation and have sent my case to Toyota Motor Poland and are waiting for feedback. It is probable that the case will be forwarded to Toyota Motor Europe. They will probably replace the actuator. However, I am pretty sure that this problem did not occur even once before the first service visit at 15 000km. They say that it's coincidence and... I am not able to rule it out, maybe it is. They still say that it's cavitation effect. I will keep you informed.

I don't get it, every Lexus I have had was extremely reliable, but always caused brakes problems. I have had an IS200t and the rear right brake was sometimes rubbing while driving (not braking), it was like a long consistent squak. I have had pads and discs replaced under warranty multiple times, but it actually never helped and I finally sold the car. It also started after a service visit. I mean... every dealership I have visited is kind of reverse Midas, everything they touch turns into ****.

Update: I have got a service appointment. Toyota Motor Poland authorized my dealership to replace the actuator. Will see if it helps...