MJN331

Hello fellow Lexus owners,

If anyone knows what's happening with my Lexus 2002 SC430, would greatly appreciate hearing from you. The dealership is now conducting electronic diagnostics and say they won't have an answer until tomorrow. What just happened to me and a passenger was a life-threatening situation -- no question a multi-fatality crash could have taken place on the busy Los Angeles 101 freeway. I just opened a case # with Lexus corporate and requested they send an engineer (or whoever) to inspect the car at the dealership. My vehicle has 135,000 miles and I keep it in excellent condition -- also take preventative care like changing the timing chain at 90,000 etc. and there are no mechanical or other problems.

HERE'S WHAT HAPPENED --

I was driving around 60 mph on the freeway and suddenly a loud shrill (alarm) went off and various dash lights came on, including ABS, VSC and maybe something else. I checked the oil light and it wasn't on and the temperature was fine. So my plan was to exit the freeway, turn the car off and hopefully the alarms/lights would not return when I restart the car -- that was the hope.

When I began to change lanes to pull off the highway there were NO BRAKES -- NOTHING! I pumped the pedal multiple times and that didn't help -- at most, I maybe had 3-5% braking power. THANK GOD I didn't panic and remembered the rules to downshift gear by gear while slowly pushing down on the parking brake. It worked and I was able to pull the car off the highway. I was with a friend and we were heading to an event at that time so we decided to leave the car, Uber back later and call a tow truck.

When I returned to the car, I thought there was a one in a trillion chance it would start with no alarms and everything would be perfect again. Miraculously, it did and it was like nothing had ever happened! I drove the car a little bit around a parking lot to test the brakes and there were no issues. I decided to drive home on familiar surface streets, no hills, where I could crawl at 10 mph in the right lane with the flashers on. I knew it would be safe going that slow and I never needed to use the parking brake to slow down the car because throwing it into low gear basically did the trick. I guess that took me down to like 1 mph and the parking brake took care of the rest.

After about 2 miles of crawling along, the same thing happened and again no brakes. I pulled the car into a gas station across the street and got it towed from there.

This morning my mechanic did a diagnostic -- he wrote down about 8 numbers and they're with the dealership now. What he was able to ascertain is there was/is some kind of a short (or whatever) in the computer system that oversees the power (something like that) to the brakes. It was a 100% system failure and the last thing the mechanic did before I towed the car off to Lexus was check some relays (switches?) that are located in a plastic box under the hood. One of them seemed to be "clicking" -- it was intermittent, maybe 2-3 clicks every ten seconds. He explained it appeared the relay is "trying" to work but can't -- that was the analysis.

I politely explained to Lexus there's no reason in the world one should have a complete loss of all brakes -- and it's not like the fluid had leaked or something. If this happened to someone who doesn't think quickly, they could have died. And if there would have been a quick stop-and-go on that freeway ahead of me, the most I could of slowed down to was maybe 20 mph -- some other unfortunate would have slammed into the car in front of them at at least 50.

I told Lexus I want a full explanation as to how this can happen -- not just for me, but for other drivers. From researching this forum and others, I found only one case like mine -- it happened a few years ago but the difference was after that fellow turned his car back on the next day, there weren't any problems at all -- and I think he's been driving the car ever since. He wrote on his post when he took it to the dealership and relayed his story, they thought he was nuts (for lack of a better word). Maybe this person is still driving the car but I'm really nervous about getting back behind the wheel of mine.

By tomorrow the dealer says they'll have it figured out. Maybe they'll want to swap out a couple of switches, or recommend a new (braking) computer system. I guess that would fix the "current" problem but if one doesn't know the underlying cause of how this happened and how it could be prevented in the future, how safe is my (and other) cars? I mean, what's to say it won't happen again and this time I'm driving down a hill? After 2002, I don't know if Lexus created some type of a preventative safety measure for brake failures, having been aware this problem was already (or could be) there. I really don't know anything on this front but this life-threatening occurrence is extraordinarily rare -- it's like you're driving your car down the street and it suddenly blows up with you in it. Final notes -- the brake fluid level was fine and my mechanic and the service manager at Lexus Beverly Hills said they'd never seen anything like this. So if you have any thoughts, it would be greatly appreciated.

As relayed above, if they're able to fix the "current" problem, where do I (and all of us) stand in the future, as far as knowing that our braking systems won't fail -- and if they did fail, there would be preventative measures in place (back-up systems or whatever) to ensure our safety and the safety of others?

Thank you,

MJN from Los Angeles

DshngDaryl

Wow! I am glad you are here to tell us the story. What a scary experience.

If I were to guess, it sounds like your brake booster failed.

Here are symptoms of a failed brake booster https://www.yourmechanic.com/article...er-check-valve

MJN331

Thank you and much appreciate you answering! I'm printing out the link you've provided.

VVTiBob

slawless

The same thing happened to mine recently (2004 59,000) It was the brake booster. Modern disk brake systems are designed to work with power brakes. you cant generate enough pressure on the pedal to stop it without the power brake booster. I had another car I was coasting down a slight incline, engine off. The brakes have a little boost reserve. When that was exhausted the car was very hard to stop. The E-brake wasn't much use either. In that case I started the car and it stopped as usual. It was a very controlled situation.

If you are curious My SC brake failure story. Fortunately mine was much less of a close call than MJN331. (I'm glad you and your SC are OK) My wife had been driving the car a lot. That day my son took the SC to work. the car was fine. He pulled into the parking space and was listening to the end of a song. Suddenly the dash lights up and the car starts screaming continuously. He shut the car off, turned it on again, same thing. He called me to ask what I thought. I told him to drive it around the building and see if it was drivable. He said it was still screaming and the brakes felt a little funny (brake boost reserve) but would try to drive it home after work. At 5:30 I get a call " Dad there are no brakes" He backed it out and it just did not want to stop. So I picked him up and called the towing service. About $2500 later, good as new. Fortunately, this did not happen with my wife driving. She would not know how to stop the car and the results would have been much worse.

Lesson to be learned. If your dash lights up and it just starts screaming at you as MJN331 describes. Get off the road as fast as possible.

GmanSC

Bgw70

Goldwinger

With the brake booster and abs unit built into one, it makes for a lot to go wrong. Brake fluid does break down and attracts moisture. The rubber parts deteriorate
and generate small particles that cause the fluid to get darker in color.

jonas's RX

I wondered if more frequent brake fluid flush would help this issue.

This is the first time I heard of complete brake failure
But even 1 time is too many times to see this happen.

wow,, complete brake failure is not a good thing.
if you are driving 75Mph and your lowered the car to
A lower gear, that probably would damaged the transmission
but I guess that is better than totaling the car not to nebrion
a full blown accident.

Hope everything works out

sixonemale

First off I was glad to read that everyone is okay regarding the incident mentioned in this thread. Secondly, what you've mentioned above is exactly what I was thinking. I've only replaced the brake fluid once with our '06 SC, but in the manual it says to "replace the brake fluid" every 30,000 miles.

MJN331

Thank you. The dealership got the car at 10 in the morning yesterday and were authorized to only conduct a diagnosis -- they said they'd call later but haven't heard back. They also know there's a case number with corporate, but haven't heard from them as well. The only good news is I like the SUV loaner car.

MJN331

Thanks for your input and happy both you and your son are okay. I don't know 2002 technology but one would like to think when they put together this car's braking system, the engineers or whoever would have asked what could theoretically cause a 100% brake failure. If there was an answer to this, would have been nice to have some kind of back up mechanism/safety measure in place that either slows down the car in some way or quickly restores the brakes. It is what it is and thanks again.

MJN331

Appreciate your good thoughts and thank you.

MJN331

Thank you so much for being so thorough, and wanting to help. There's so much critical info you provided and it'll be put to good use in figuring things out.

MJN331

Didn't hear about the brake fluid going "bad" and causing problems until now. I keep every service receipt and I'm pretty confident we either flushed the system and/or checked to ensure the coloring etc. looked okay. Thank you again for your kind reply.