Brake failure. Trying to figure out what happened.
#16
Lexus Test Driver
The service history could show if the brakes were ever bled. Never bleeding brakes could be the reason you had brake MC failure.
Why do you say it is electronics?
#17
Rookie
Thread Starter
I just thought you might be interested in seeing any maintenance performed by Lexus, if any...it’s a nice service provided by Lexus. I have the Lexus service history on both of my SC430s.
The service history could show if the brakes were ever bled. Never bleeding brakes could be the reason you had brake MC failure.
Why do you say it is electronics?
The service history could show if the brakes were ever bled. Never bleeding brakes could be the reason you had brake MC failure.
Why do you say it is electronics?
#18
Lexus Test Driver
It wasn't soft like brakes that hadn't been bled. It was a momentary grab followed by complete to the floor failure. They would have been soft long before you'd have a failure. I know what air in the lines feels like. In addition, once I started the car to move it, the brakes were fully functional again.
Never had major brake failure like you and others, but did have a bad leak on my 2002 SC430 BMC shortly after I made the purchase.
Replaced it with a $100 unit from a 2005 in a salvage yard. Still good several years later.
Here are my two cents...When the fluid is never changed and the fluid is black, caused by water/condensation entering the system, the seals in the MC piston can fail which allows fluid to pass by them causing the pedal to move to the floor rapidly.
or the lack of fresh fluid in the ABS controller causes a similar problem with the ABS valves sticking open.
I say that because in three cases I know of, the driver pressed the brakes very hard...perhaps enough to engage the ABS.
Last edited by Bgw70; 01-03-21 at 04:24 PM.
#19
Rookie
Thread Starter
What do you think failed?
Never had major brake failure like you and others, but did have a bad leak on my 2002 SC430 BMC shortly after I made the purchase.
Replaced it with a $100 unit from a 2005 in a salvage yard. Still good several years later.
Here are my two cents...When the fluid is never changed and the fluid is black, caused by water/condensation entering the system, the seals in the MC piston can fail which allows fluid to pass by them causing the pedal to move to the floor rapidly.
or the lack of fresh fluid in the ABS controller causes a similar problem with the ABS valves sticking open.
I say that because in three cases I know of, the driver pressed the brakes very hard...perhaps enough to engage the ABS.
Never had major brake failure like you and others, but did have a bad leak on my 2002 SC430 BMC shortly after I made the purchase.
Replaced it with a $100 unit from a 2005 in a salvage yard. Still good several years later.
Here are my two cents...When the fluid is never changed and the fluid is black, caused by water/condensation entering the system, the seals in the MC piston can fail which allows fluid to pass by them causing the pedal to move to the floor rapidly.
or the lack of fresh fluid in the ABS controller causes a similar problem with the ABS valves sticking open.
I say that because in three cases I know of, the driver pressed the brakes very hard...perhaps enough to engage the ABS.
If you check one of the first links on this thread you will see a similar issue reported..
#20
Dbryan, so glad you are okay. That sounds terrifying. I remember the other post from a couple years back.
I w/ ask about brake bleeding w/ my mechanic. Is there something to proactively check w/ the MC? I will go back to those links and re-read.
What would happen if one tried to pull up the parking brake should something like this happen? Providing one had the wherewithal!
I w/ ask about brake bleeding w/ my mechanic. Is there something to proactively check w/ the MC? I will go back to those links and re-read.
What would happen if one tried to pull up the parking brake should something like this happen? Providing one had the wherewithal!
#21
Lexus Test Driver
First, I was using normal pressure when they suddenly failed. Secondly, they functioned properly when the car was turned off and then back on again. Thirdly when I have the oil changed, the shop always examines all the fluids and it was fine. Finally the first time I brought it in I specifically had the brakes checked as per usual whenever I buy a car. It was not brake fluid. I am certain.
If you check one of the first links on this thread you will see a similar issue reported..
If you check one of the first links on this thread you will see a similar issue reported..
https://www.aboutlawsuits.com/toyota...-recall-99756/
https://www.mechanicsdirect.com/blog...us-is-failing/
http://www.diy-time.com/automotive/t...ta-lexus-cars/
#22
Rookie
Thread Starter
not our model or year but it is happening...
https://www.aboutlawsuits.com/toyota...-recall-99756/
https://www.mechanicsdirect.com/blog...us-is-failing/
http://www.diy-time.com/automotive/t...ta-lexus-cars/
https://www.aboutlawsuits.com/toyota...-recall-99756/
https://www.mechanicsdirect.com/blog...us-is-failing/
http://www.diy-time.com/automotive/t...ta-lexus-cars/
This describes it pretty well
Popping/Clicking Sound
There have been various loud sounds reported to occur immediately preceding brake actuator failure. Though the descriptions of the sound may vary, they are all loud and consistent. The loud sounds likely result from the pressure leaking rapidly from the brake system, as the brake actuator fails to regulate the pressure.Sudden Brake Failure
The worst and eventual result of brake actuator failure causes a sudden failure in the braking system. Since the brake actuator is responsible for both immediate braking and the parking brake, this can occur at nearly any time. Owners have reported the sudden failure at many different speeds, including braking to slow a vehicle as well as intentional stop braking. Failure, while parked with the parking brake engaged, has also been reported to result in diagnosing brake actuator failure.
#23
Pole Position
Hey BGW, didn't you once say that Lexus has a rebuild kit for the master cylinder? Something relatively new, since you had to buy a used one the time you had a problem.
Though the master cylinder is expensive to replace, it might not be too bad for people to have their cylinder "rebuilt"
Ah heck, I guess I should just google "Sc430 master cylinder rebuild kit" and see for myself
https://www.lexuspartsnow.com/oem-le...epair_kit.html
Though the master cylinder is expensive to replace, it might not be too bad for people to have their cylinder "rebuilt"
Ah heck, I guess I should just google "Sc430 master cylinder rebuild kit" and see for myself
https://www.lexuspartsnow.com/oem-le...epair_kit.html
#24
Lexus Test Driver
Hey BGW, didn't you once say that Lexus has a rebuild kit for the master cylinder? Something relatively new, since you had to buy a used one the time you had a problem.
Though the master cylinder is expensive to replace, it might not be too bad for people to have their cylinder "rebuilt"
Ah heck, I guess I should just google "Sc430 master cylinder rebuild kit" and see for myself
https://www.lexuspartsnow.com/oem-le...epair_kit.html
Though the master cylinder is expensive to replace, it might not be too bad for people to have their cylinder "rebuilt"
Ah heck, I guess I should just google "Sc430 master cylinder rebuild kit" and see for myself
https://www.lexuspartsnow.com/oem-le...epair_kit.html
I never bothered to purchase one since I was able to locate the salvage yard BMC. But I almost did because I was desperate. Never could locate the source of the leak.
I still believe one of the contributing factors for failure is not keeping the fluid serviced.
It seems this only happens to the first generation SC430s.
Does anyone remember any 2006-2010s failing?
#25
Rookie
Thread Starter
yep, that would be the one...a new BMC piston and O-rings.
I never bothered to purchase one since I was able to locate the salvage yard BMC. But I almost did because I was desperate. Never could locate the source of the leak.
I still believe one of the contributing factors for failure is not keeping the fluid serviced.
It seems this only happens to the first generation SC430s.
Does anyone remember any 2006-2010s failing?
I never bothered to purchase one since I was able to locate the salvage yard BMC. But I almost did because I was desperate. Never could locate the source of the leak.
I still believe one of the contributing factors for failure is not keeping the fluid serviced.
It seems this only happens to the first generation SC430s.
Does anyone remember any 2006-2010s failing?
#26
Lexus Test Driver
I should add that I also believe Toyota had some issues with our SC430 BMCs but there just weren’t enough malfunctions or enough people shedding light on the problem.
Our BMC is complex and expensive because it does it all in one unit...BMC, ABS, pump and accumulator all in one. I want to say the GS430 had an identical unit with its own share of failures.
I believe One of the articles I posted was a class action lawsuit for another Toyota model.
Lets face it, Toyota only uses so many subcontractors to produce their parts.
Last edited by Bgw70; 01-04-21 at 12:35 PM.
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dbryan (01-05-21)
#27
Driver School Candidate
Really sorry to hear about this and am also glad your okay. It's a scary thought to even have about any vehicle yet alone one being serviced regularly by the dealership. I also have an 02 sc430 and am concerned as well. I have had mine since a little under 100k miles and am up to about 175k miles. I did the supra tt front brake upgrade along with the stainless steel lines and saw a major improvement in braking.
#28
Pole Position
yep, that would be the one...a new BMC piston and O-rings.
I never bothered to purchase one since I was able to locate the salvage yard BMC. But I almost did because I was desperate. Never could locate the source of the leak.
I still believe one of the contributing factors for failure is not keeping the fluid serviced.
It seems this only happens to the first generation SC430s.
Does anyone remember any 2006-2010s failing?
I never bothered to purchase one since I was able to locate the salvage yard BMC. But I almost did because I was desperate. Never could locate the source of the leak.
I still believe one of the contributing factors for failure is not keeping the fluid serviced.
It seems this only happens to the first generation SC430s.
Does anyone remember any 2006-2010s failing?
#29
Lexus Test Driver
What years, is it the O-ring, is it contamination, does it happen more to cars in a certain climate, etc.
We just know it happens and the only answer I have seen is Toyota telling people they need a new $$$$ BMC.
#30
Rookie
Thread Starter
What's worse is why does the computer sensor disable the brakes? Even mushy brakes would be better than no brakes. If this is Toyota's/Lexus' attitude maybe there is a class action suit waiting for someone to take on. This seems more deadly to me than the airbag issue