jiboom

I have a 2008RX 400H. Barking noise while pressing brakes has become increasingly worse over the past month. No warning lights on dash. My independent mechanic said the actuator is going. Do I have any chance of getting this fixed by Lexus as it is a known problem but past the extended time. If not is it worth considering a used actuator. Thanks for any advice!

gwgang

This reply may be too late, but I would share my experience. My brake had been barking since I got it used 11 years ago. It's still barking, but otherwise no performance degradation. I wouldn't worry about it until it fails. Chasing after this problem only cause wallet drain, not solution.
What is my "barking brake" symptom? When my RX400h is stopped with my foot on the brake, and I proceed to increase pressure on the brake, the brake system will make "barking" noise. No abnormal noise is observed when applying brake during driving, high speed or low speed, or when coming to a stop.

Attempted repair effort: Replace front brake rotors -- total scam by a previous repair shop I used.
Master cylinder replacement suggested -- I didn't do this. My brake is working fine.
ABS software reset/update -- done by Lexus dealer, didn't fix the noise. Fortunately I didn't pay for it.

ukrkoz

Brake actuator should prime once after start up and then after complete shut down, about 10 seconds after.
That's it. No repetitive noise should be occurring otherwise.
I'd be very careful with neglecting brakes malfunction though, it needs to be mentioned, that hybrids are drive by wire brake by wire cars and, when electronic side of that fails, they switch to regular hydraulic braking. It's double safe design feature though, having no brake booster (that's what accumulator/actuator are for) will make it hell of fun to slow down in emergency.

gwgang

A malfunction light will lit up if electronic parts fail. Hydraulic power works just fine stopping the car. The electronic part is used when the computer decided to use regen to slow the car instead of using the brake. When you are braking while driving over a bump, you will feel the release of the electronic brake control, and hydraulic brake takes over. You will experience this as a slight surge in speed vs smoothly slowing down.

There was a TSB for ABS system to fix customer compliance of brake noise. I don't think it really works.

myw

this happened on my previous Rx400h - i just ignored it. never caused a performance problem at all - but it did make the barking noise. i expect it to happen with my current rx400h as well.

iMSQ

Could you please explain what it is? Thanks.
PS: Simple situation: pressing brakes -> sound -> replace the braking pads

ukrkoz

Brake actuator is making a sharp staccato noise when it primes. Some could call it barking. It primes right after system starts and then releases valves, with same noise, after shut down.

Toyota hybrid system braking is set up so that it favors regenerative braking over hydraulic. That means that regen braking comes FIRST and, if demand for slowing down vehicle is not satisfied, THEN hydraulic braking is employed. Not computer deciding whenever it wants to do this or that. System is set up so that 80% of braking power is supplied by regen. Yes, in normally functioning brake system you will have hydraulic pressure assistance from brake accumulator and actuator. Not so much if actuator fails.
Look under the hood. There is no hydraulic lines running from master to calipers. They all go into large black cube and from there - to calipers.

iMSQ

When my actuator was dying it was pumping most of the time when the engine was ON. There was no barking sound, only pumping sound.

riredale

To a lot of us, it sounds more like a barking seal. Lots of threads about the issue. It's the ABS actuator and Lexus wants thousands of dollars to replace it.

There's more on this thread:

https://www.clublexus.com/forums/hyb...ctuator-2.html

In particular, go to my comment on the above thread on October 9, 2018. In that reply I also include some audio that demonstrates the sound.

This really should be a class-action suit. Lexus RX is a great car, but it should never bark like a seal.