70 mph on expressway - very shrill alarm sounds, brake and several other related lights come on, depressed brake pedal all the way to floor - only about 3% brakes. If there had been heavy traffic this could have been life ending for me and another driver. Coasted to stop, then drove, in low gear with foot near emergency brake, to my house. Searching this forum, I found two other instances with exact symptoms in 2018 in CA. Lexus Guest Services was no help. Could not find an independent repair shop that would agree to look at the brakes since programming the computer is necessary. Had car towed to Lexus dealer for $85, then Lexus replaced the entire electric booster assembly to the tune of $2,850. I believe Lexus has been negligent by not notifying owners that this condition could happen - and it obviously is a known defect in the electric activated booster system.

 

Flasun, can you ask Lexus to pay under goodwill ?

This sound like it is happening in many SC430 and
for sure a critical part like this should never go out.

This is not like a gasket going out due to age. The MC
should never go out unless the system was defective

 

Goodwill - unless you spend a lot of money with Lexus, my guess is it's not going to happen. This also happens on the LX470 (lot more of those out there than SC430s) and nobody I know is getting any "goodwill"

 

Darn, this is scary. I notice that all of the incidents have happened to SCs with high mileage. What preventing maintenance can we do to avoid this deadly failure when our SC getting old?

 

Having owned a 100 series LX470 for some years, I always dreaded a possible brake failure. There is/was ~290 reported failures on LX470/Land Cruiser trucks on the IH8MUD forum.

IIIRC, two themes were most prevalent:
1. The "traditional" part of a master cylinder fails. This is the piston/seal that gets moves down a cylinder applying pressure when brakes are applied. Several IH8MUD members reported out how they bought a replacement piston and seal kit. This sort of thing just happens over time as seals wear out (happened to me on a 5 year old Plymouth). Also, failure to do brake fluid maintenance may lead to rust pitting in the cylinder walls that the piston/seal slide through, contributing to seal failure.
2. The electrical motor that drives the accumulator pump simply wears out the brushes/commutator. This is also an aging thing. Again, on IH8MUD, the most common failure (also IIRC) was to trucks with around 150K miles. Rebuilding the motor worked for some, other had to purchase new or used unit.

There are hundreds of brake failure pages on to read through over there. I was a lucky one. I sold my LX470 before I ever encountered it, and it had 225K miles on it when I sold it.

 

I guess I am a lucky one. I sold three Toyota cars that had the mileages above 250k miles: 343k, 300k and 260k, none of them have developed brake failure. So it’s bit of comfortable but still scary if you think about those incidents.

 

I should be entered into both columns. Col A - MC failed, and Col B - lucky one.

I was working with the seller to buy the SC430 I'm driving when the MC failed for him just 2 days before I was to pick it up (we had a weekend deal scheduled).

He agreed to pay for the whole repair bill as a condition of the sale for no additional dollars. Took a few days to get parts in then another day to get it repaired.

Car has 107K miles.

 

What is most disturbing is the "total failure" scenario. Neither of the two "common" issues oneround reported on above should lead to a total failure, as brake systems are supposed to be designed to be "fail-safe," even when one component fails. If they are not, and the OP's post is 100% legit in reporting a 97% failure (total in my book), than Toyota/Lexus should be investigating their design and taking corrective measures before the tort lawsuits begin!

 

Also own a Mercedes R230. They recognize a similar issue and gave a 20 year extended warranty for their brake system issue. Had this happen with mine with only 54k it appears to be more time / age related rather than mileage.

 

Need to find a lawyer that wants a juicy lawsuit and they need to throw it at Toyota for being negligent. This **** should NOT be happening at all, and is beyond ridiculous regardless of age of the car. This is critical and could end up with someone being killed or hurt at best.

Toyota needs to step up and address the issue and apply a fix for this. They are acting clueless on this when they know exactly what is going on.

I swear this **** behavior is like how the American car companies acted with major recalls and did nothing until injuries/death occurred. On top of that you’re driving your car and this bull**** happens and there’s an accident you end up getting blamed by your own insurance company along with any others that are involved it’s absolutely ****ing ridiculous!!!

I have this in the back of my head every time I drive my SC. I may just look into replacing the system before it has a chance to fail on me. I don’t drive my SC much and it’s only for fun, but I’m modding the car and building up an extra engine - the car will have a lot more power and should be a lot faster and will be driven in a spirited fashion once the aftermarket suspension and big brakes are installed. Last thing I wanna worry about especially after the modifications is for the brake system to fail on me. I live in Los Angeles and there’s always a lot of traffic and if it fails in a situation where I need the brakes to stop the car it could be disastrous.