Do we have brake override?

[yaris-me]

The Yaris has not been recalled but do we have brake override?

http://www.youtube.com/watch?v=VZZNR...ayer_embedded#

[Yaris Hilton]

Nope. And it'd kill the awesome dragstrip prowess of an automatic Yaris if you couldn't stand on the brakes, hit the gas and slip your foot off the brake as the light goes green.

[Loren]

Geez, people. If the throttle sticks, put the car in neutral, shut off the ignition and stop. It's that simple.

No "brake override" necessary. Just use your head.

[Tamago]

Originally Posted by Loren

Geez, people. If the throttle sticks, put the car in neutral, shut off the ignition and stop. It's that simple.

No "brake override" necessary. Just use your head.

tell that to the people with smartkeys lol

but yeah, i agree with you

[Loren]

Originally Posted by Tamago

tell that to the people with smartkeys lol

but yeah, i agree with you

I've yet to see a car that doesn't allow you to shift to neutral or push in the clutch. Or one (smart key or not) that doesn't have a means for the driver to turn off the engine. This "brake override" BS is just someone trying to cash in on the hype.

[41magmag41]

Who needs a brake override when you have an attorney on retainer.

[BLH]

In the automatic. The shift selector tells the ECU to change to neutral. Get the ECU confused enough and maybe it will not shift into neutral. Manuals no contest. Move to neutral it is in neutral.

[sbergman27]

Originally Posted by BLH

In the automatic. The shift selector tells the ECU to change to neutral. Get the ECU confused enough and maybe it will not shift into neutral. Manuals no contest. Move to neutral it is in neutral.

But what if the manual transmission's shift lever jams? What if I'm in an elevator and the cable breaks and all the secondary safeguards malfunction? What if I'm having dinner in a revolving restaurant and there's a power surge which slings me through the window to my death, while the remaining diners must deal with the Ginsu Knives that come flying out of the kitchen as the restaurant spins up?

Or maybe... just maybe... none of these things are very likely? Maybe people are simply irrationally distrustful of software. And maybe... just maybe... the historically dismal quality of consumer grade software like... well... Microsoft Windows... has done a lot to fuel that irrational distrust.

But the embedded software world is a completely different ball game. Particularly when that embedded software is controlling critical systems. People view the ECU as though it's running the same slap-dash software as their ever-problematic laptops. And it just ain't so.

-Steve

[yarrr]

^^ lol well said

The yaris doesn't have brake override, but like most vehicles, has a lot more brake horsepower than wheel horsepower.(slam on the gas and brake to see)

[Loren]

Originally Posted by BLH

In the automatic. The shift selector tells the ECU to change to neutral. Get the ECU confused enough and maybe it will not shift into neutral

I just looked at the service manual (since I don't own an automatic), and there is a physical shift cable from the shifter to the transmission. I don't think it's possible for the ECU to override you physically putting the transmission into neutral.

Interesting side notes:
You can uplug the electronic shift cable from the transmission and drive the car shifting manually using the shift lever. (this is listed as a test procedure to verify that a shift-related fault is electronic and not within the transmission itself)
The lock-up torque convertor only locks in 4th gear above 37 mph. (this is why people who accidentally drive around with the stick in 3 get such poor MPG)

It's amazing what you can learn by reading the manual.

[QR25DE_SpecV]

Originally Posted by Loren

Geez, people. If the throttle sticks, put the car in neutral, shut off the ignition and stop. It's that simple.

No "brake override" necessary. Just use your head.

Absolutely not. Never turn the ignition off and try to come to a stop. Without the engine running you're no longer producing vacuum, which your brake assist runs off of. No vacuum = no power brakes equating to pretty much zero stopping power.

Correct situation is to put the vehicle in neutral, let the engine redline, and come to a controlled stop.

If for what ever reason you lose power brakes, you still have the emergency brake. You just have to make sure you don't lock up the rear wheels.

[sbergman27]

Originally Posted by QR25DE_SpecV

No vacuum = no power brakes equating to pretty much zero stopping power.

No. The Yaris doesn't really need power brakes. And you can stop the car just fine without them. You *will* need to push harder. But your grandmother could probably lock all four wheels with the power disabled.

Being *surprised* by a lack of power assist could be a problem. Especially if you have other stuff on your mind. e.g. if you are coasting in neutral with the engine off and something completely unexpected happens, which requires immediate action.

-Steve

[sbergman27]

It's probably worth highlighting some points which differentiate the ECU's software from the buggy crap that people are used to dealing with:

1. Embedded software is more like server software than it is like desktop software. It has a very well defined set of inputs and outputs. And the software itself is not very complex at all. The number of lines of code is likely quite small. It's absolutely nothing like the average email client, or browser, or spreadsheet. All of which are vastly, unimaginably, more complex pieces of software, which must deal with vastly more varied, unpredictable, broken, and even hostile input. Particularly in the case of email clients and browsers. e.g. the vast majority of web pages on the Internet use sloppy, invalid, broken, HTML and ECMASscript.

You can validate the simple main page of YarisWorld.com:

http://www.yarisworld.com

right now if you like:

http://tinyurl.com/y9atgsu

See what I mean? Your browser has to guess what the author meant by that train wreck of broken HTML and do its best to display it right. It has no check engine light to turn on.

2. The ECU software engineers have it even better than Apple's. The PC world is a hardware free-for-all. But Apple engineers have the tremendous advantage of controlling the base hardware. They don't have to worry about what SATA controller Dell decides to use on a low-line laptop. But they do have to worry about what third party video cards, etc. the user might install. The Toyota engineers control the hardware in a very profound way. Even more so than Apple.

3. All this makes testing much easier and more straightforward. The variable's are so greatly reduced. And test they do. Because if the software fails... you don't just lose all that work you put into your nifty-difty spreadsheet that you were so busy working on that you forgot to save. These companies know that they'll get a very bloody nose if they make a mistake. There is a huge incentive to test thoroughly, no doubt with lots of paperwork shuffling back and forth, to and from Toyota Legal. That's another typical hallmark of embedded software.

Unfortunately, it seems that they are also vulnerable to getting a very bloody nose even if they *don't* make a mistake.

-Steve

[Loren]

Geez again.

Everybody... go find yourself a deserted back road somewhere where you have plenty of space and nobody around. Accelerate to 45 mph, turn OFF the ignition and try to stop your car.

Now, do the same thing again, only press the brakes lightly several times before actually trying to stop the car. This will deplete much (maybe all) of the brake booster vacuum. You'll know when you run out of vacuum, the pedal will get harder. Then stop the car. It will take a bit more pedal effort than you're used to, but you CAN still stop the car.

Do the same thing from 60 if you need to, just to give you more time to bleed all the vacuum from the brakes. Feel what it feels like. Know what to do. Someday you might find yourself in a situation where your engine has quit, or some mysterious vacuum leak has occurred, or some part of your brake booster has failed... it's GOOD to know what this feels like, and it's good to know that you don't need to PANIC and assume that the car doesn't have enough brakes to stop. It does.

Aaaaaand, just to be sure I'm not leading anyone astray, I just went out and TRIED IT. 45-60 mph, cut the ignition, press the brakes a few times (it takes 6-8 presses just hard enough to get the brakes to engage to deplete the vacuum), and then stopped the car with no power assist. Does it take a lot more pedal effort? Yep. Is it impossible? Far from it.

Again, TRY IT. This is one of those things that could save your life someday. The more you know, the less likely you are to panic when something goes wrong.

Oh, and if I was recovering from a stuck throttle, I wouldn't waste those 6-8 presses of the brake pedal... I'd simply find a place to pull over and brake ONCE to stop... and I'd have full assist to do it. (you might want to try that, too... just to prove it to yourself)

[bronsin]

This is what the media did to Audi in the 90s. Basically drove Audi from the US market.
None of it true. (car shifts itself into drive and accelerates)

[sbergman27]

Originally Posted by Loren

Geez again.

Want to hear something *really* amusing? My Chevy Sprint, curb weight 1680lbs... and that's 33% lighter than the Yaris, and a featherweight car by any standards... has power brakes. (My brother chides me by calling it my "turbocharged go cart". Though I steadfastly remind him that it's not turbocharged.)

What in the world did all those drivers of pre-1930 5,000lb Cadillacs ever do without power brakes? Careen around and crash into each other, I guess. I've been in positions, over the years, where stopping my 5200lb '68 Fleetwood, without vacuum, was called for. It's definitely more difficult. But doable. Not a job I'd put my grandmother on. Especially since she's dead.

Interesting point about manual shifting. I drove a 1992 Geo Metro for a while where the automatic shifting was (very) unreliable. Not knowing what it was going to do was more annoying than just doing it myself. So I disconnected its shift solenoid connectors, and treated it like a semi-automatic. Manual shifting... but with no clutch to mess with.

-Steve

[IllusionX]

i really wish people weren't so stupid.

i mean.. com'on! those vanhool busses are DBW, does not require a key (push start) AND have electronic shifters... i have yet to see one that are faulty enough to have such problems...

[sbergman27]

Originally Posted by IllusionX

i really wish people weren't so stupid.

I wish more people sat and thought about things. Bandied ideas around in their minds. Did thought experiments to examine how reasonable this or that assertion was in light of other things they know.

I wish that we did not live in such a "tabloid" world. It's not about stupidity... which is a label. It's about a willingness to employ critical thinking.... which is a behavior.

No offense intended to you, IllusionX. But I wanted to make that distinction.

-Steve