Not everything I mentioned may be 100% accurate so please feel free to offer any corrections. I always try to improve the quality of this forum in my posts by presenting issues and following up with solutions when I have them.

Issue:
Buddy of mine has a 2013 and I have a 2014 LS460, for which both car have the C1391 code "Accumulator Leak" in brake actuator. Between us, we've owned 6 LS460s. Brakes pulsate when slowing down and any slightest increase in pressure on the brake pedal results in pulsation (the feeling of overpressure brakes grabbing/soft). Driving and braking feels normal otherwise other than having 6 warning lights and 3 warning messages on the dash LOL. Our 2008, 2009, 2011, 2012 never had the brake actuator issue despite having over 100k miles each.

History on car:

• 2013 LS460L w/50k miles: All serviced intervals performed by dealer especially the 30k & 40k interval; Located in South Texas
• 2014 LS460L w/60k miles; All service intervals performed up to 50k; Located in New Mexico

Brake Actuator information:

• 2007-2012 came with the 44050-50090, 44050-50130 actuator replaced by 04003-45450 (2016 per ZLG warranty) and later replaced by 44050-50110 (found in 2013+ models)
• 2013-2017 came with the 44510-50070, and 44050-50110 Actuator

The 2016 L-SB-0083-16 dealing with the brake actuator squawk/bark noise recommends replacing 44050-50110 with the same model 44050-50170 actuator if repair procedures do not remedy the noise.

The most recent 2019 L-SB-0047-19 dealing with the brake actuator squawk/bark noise recommends replacing 44050-50090, 44050-50110, 44050-50130, 44050-50150, 44050-50170 actuators with 44050-50170 if repair procedures fail to remedy the noise.

As you can see 44050-50170 actuator squawking noise mentioned above is to be replaced by the same model actuator 44050-50170. Someone help me out here, but by this I'm going to assume 44050-50170 is the most recent or updated revision which still has a problem. It seems like Toyota has tried update/revised to the LS's actuators for quite some time now and there is a ton of actuators with various old part numbers being sold out there by ebay resellers and Toyota/Lexus dealers.


Questions and comments:
I looked at my 2014 vehicle and found no leaks in or around the actuator or brake lines and the brake fluid reservoir remains normal. I'm thinking a fluid flush and linear valve offset procedures may fix the problem. But if not, then i will assume the voltage on the solenoids are out of range thus triggering the light or that there is a pressure imbalance inside the actuator that cannot be corrected. I dont fully trust Lexus diagnostics but I have 3rd party warranty so i want the dang thing replaced. My buddy is out of luck on his 2013 with no warranty. Both our cars are relatively low miles and I mentioned the 30-40k service interval done above because that was when the brake fluids were changed. My understanding is that old fluid absorbing moisture may cause corrosion inside the actuator in addition to what i would call a design and material defect in the actuator.

-I want to know if this is still drivable? (of course i have driven the car, just don't know if it's safe)
-Does anyone use any a superior synthetic fluids for their brakes instead of using Toyota fluids?
-Is there a brake fluid that claimed or has proven that it is less prone to absorb moisture?
-Would a failing brake actuator cause the brake booster pump to fail? I know some complaints had this issue as well as the actuator.


Please report this to the NHTSA. My buddy is a lawyer and is considering filing suit to force Lexus into arbitration.

 

 

I got an impression that Lexus sometimes uses sub-assembly numbers in TSBs. It makes it nearly impossible to track down through public parts data bases. If I use parts.lexus.com, I get the following:
It is interesting to note that the latest part number is actually not the highest number.

Did you replace the fluid every 24 months?

 

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I'll answer the questions you posted from my experience in dealing with Lexus/Toyota brake systems. However, I have a question for you. Did you and your friend follow Lexus LS460 brake maintenance schedule - replace brake fluid every 36 months or 30K miles, whichever comes first? From my experience, replacing brake fluid per Lexus/Toyota maintenance schedule is the key to avoiding the failure of Lexus/Toyota brake actuator assembly. This is especially true for LS460 and Lexus/Toyota hybrid vehicles. Now, my answers to your questions:
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1. It's never a good idea to drive a car with brake problems. It is a risk to yourself and other drivers on the road. Brake problems, however minor or small, should be fixed ASAP.
2. Ideally and preferably, Lexus brake fluid (part number 00475-1BF03-LX) should be used. In reality, any reputable DOT3 brake fluid (e.g., Prestone) is fine if you replace brake fluid per Lexus maintenance schedule. On US market, all DOT3 brake fluids are synthetic. I have been using Prestone DOT3 on all Lexus/Toyota cars that I worked on and have not experienced absorbing moisture issues.
3. Every brake fluid manufacturer claims that their brake fluid meets or excels OE brake fluid standards. If you want to have a peace of mind, go with Lexus/Toyota brake fluid (00475-1BF03-LX)
4. In theory, a degrading brake accumulator causes the brake pump/booster to press and depress frequently, thereby causing more wear and tear on the brake pump/booster and shortening its lifespan.

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Thank you for the response! Fluids were flushed in their 30-40k service but not every 24 months. I haven't heard of anyone flushing their fluids every 2 years. (I guess we all should.) I was wondering if the brake booster plays as an ancillary component to the actuator in the LS. By installing the actuator, they've reduced the size of the brake booster significantly. The actuator modulates braking force based on driving conditions while the brake booster provides pressure overall to the system?

 

To follow up, Lexus doesnt know is the current part number. Contacted multiple dealers and also Lexus corporate who says "the system" tells them that 44050-50110 is the replacement. When I showed them both LSB's saying to replace 44050-50110 with 44050-50170, they did not have an explanation. This is a $3k service and this response is not acceptable.

One lexus dealer who gave me a quote noted that some wiring harness should be replaced bc they tend to go bad. I am not sure which harness this is that sits by the brake system.

 

Does your cover have a warranty? I wonder if LSBs are applied to recalls and warranty replacements.

 

There's an internal tmc bulletin... Only one number in this thread is a correct 'fixed' replacement one. All others are defective. Even 13+ ones. I can't divulge which one is correct, as tmc will fry my *****. Again.

 

I'd just like to add two things, one being an answer to your question whether or not you can drive with a failing actuator, and I'm paraphrasing miket here, "You can but eventually it will fail completely, requiring you to press the brake pedal very very hard and it will still stop relatively slowly." He didn't recommend driving it into the ground this way.

The other being in regards to brake fluid flush, I now realize that I did mine incorrectly and unless you have the document that tells you exactly what to do, it is super easy to miss steps. I didn't perform accumulator zero down, which I suspect is the small amount of brake fluid stored in the VSC/ ABS system. Don't know what exactly the linear valve calibration does but I didn't do that either and my barking/ clicking is still ongoing as a result. As you can probably figure out, if you skip the accumulator zero down, the old and moisture soaked fluid remains inside the actuator.

tl;dr read the Toyota document that tells you how to change brake fluid and don't skip any steps in techstream

 

My warranty covers part and labor but only at average market rates. So they will cover $100/hr per labor but lexus charges $200/he so i have to pay the difference.. Avg market rate for the 44050-50110 is $1150 but my dealers is charging $1750, so i pay the difference. The point is the severity of the failure is why i try to raise hell. My fluids were changed by the dealer at the 30-40k service interval so i assumed they did it correctly.

I finally sat down and went over the FSM and some online literature on toyota brake actuators. It does seem like the brake booster pump provides pressure to the brake actuator and with the loss of pressure detected inside the actuator, the brake booster pump has to recharge the pressure. Normally you would hear this pressurization sound every 50 secs or few minutes(?) on a normally working unit but with my leak in the actuator, I can hear the pressurization sound every 8 seconds. So even with the car not being driven and only idling while in park, the leak in the actuator would still cause the brake booster pump to overwork to failure. It has to continually run to compensate for this leak even if the car is not moving.

In other related news: the LS500 also are already having brake actuator issues...

 

Scary. I've been eyeing 2013+ LS460 to buy in the next year or so with the false assumption that the major issue of brake actuator being fixed in those year models. After having an LS430 for almost 8 yrs now it's hard to find anything that will live up to it's quality, comfort, and drive ability but at some point I'm going to have to move on to a new car. LS460 are still commanding very high prices for their mileage and age.

 

The sad part is Toyota doesn't give a damn. The money is in the rav, rx and other crossovers.

 

Lexus/Toyota should provide an extended warranty on actuators as these are failing in several models. I suspect there are several reasons that they fail.

1. The brake fluid replacement maintenance is very complicated, needs 2 people and is very risky to create codes and issues. I suspect that sometimes dealers and other mechanics just replace the fluid on the reservoir and call it a day. Many advisors avoid writing brake fluid changes since they can not charge much and it is time consuming and a risky procedure. When we do DIY, not only we need a second person but we running risks of losing communication with Techstream, depleting the battery, having codes and or somehow manage to leave air in the system. Bottom line very few vehicles have replaced properly brake fluid every 30 months. For example on 2014 the fluid should be already replaced 3 times.
2. The Toyota DOT 3 fluid appears inadequate as actuators are failing. They seriously need to upgrade to the lower viscosity DOT 5.1 not only for max temperatures but more importantly for anti corrosion and lubricating properties.
3. The actuator and brake system needs to be redesigned so the brake fluid changing is straight forward for the average mechanic and actually being completed.

 

DOT 5.1 is so expensive though!

 

The brake actuator went out in my 2010 460L with 101k miles. I ordered the part from Lexus of Mobile for $1050 shipped and my local Toyota dealership installed it for me for $715. They usually wouldn't replace parts that a customer brings in but since it was an OEM part still in the box they were ok with it. Lexus dealership wanted $3800 for parts and labor to do the job.