Originally Posted by 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

Originally Posted by ejthomas

I'm perusing this thread as we just purchased a near-mint 2002 SC430 with 52k miles. On startup first thing in the morning, I hear an on and off "screech" that appears to be associated with the brake system pump/accumulator. Once it cycles a few times, the pump shuts off and I have no problem for the remainder of the day. No lights on the panel, and the brakes work fine. I'm wondering if this unit is on its way to failing, and the bird-of-prey screeching is advance warning... Thanks. E.J.

Originally Posted by ejthomas

Thanks for your reply... I wasn't clear in stating that the screeching noise is when the car is in Park and not moving.

Originally Posted by ejthomas

I'm perusing this thread as we just purchased a near-mint 2002 SC430 with 52k miles. On startup first thing in the morning, I hear an on and off "screech" that appears to be associated with the brake system pump/accumulator. Once it cycles a few times, the pump shuts off and I have no problem for the remainder of the day. No lights on the panel, and the brakes work fine. I'm wondering if this unit is on its way to failing, and the bird-of-prey screeching is advance warning... Thanks. E.J.

Originally Posted by ejthomas

Thanks for your reply... I wasn't clear in stating that the screeching noise is when the car is in Park and not moving.

Originally Posted by ejthomas

Here's a short clip that I took behind the wheel. At the time, I wasn't sure if it was under the dash or hood. I figured out that it's the MC assy later, but in watching the video, one can hear the pump cycling. And always, once the cycling stops, the screech went away. BTW, at no time have I seen any warning lights on the gauge cluster. Thanks!

Originally Posted by ejthomas

For some reason, I'm unable to get the clip attached, although it's under the size limit and appears to pull from my computer file. But then I don't see it in this (or the last response). Could be pilot error here...any suggestions? Thanks!!

Originally Posted by JDaveSC430

Why in the world wouldn't this be a priority safety complaint to the TSB? I have an 02 72 k miles, have new brakes and serviced and changed fluid and never had a problem but, this worries us all. Whoever has had this should call the TSB hotline FROM A LEXUS DEALER'S service manager's office on speakerphone!!! Maybe have an auto lawyer available for consult. Damn!.