×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

The ignition switch?
7

The ignition switch?

The ignition switch?

(OP)
Does anyone know what year and what manufacture started to use a computer to control the ignition switch. I'm sure every auto now has this feature, and the start stop technology is proof it exists.
I am particularly curious if a 2009 Honda CR-V has this type of ignition switch. Because if it does then it will need a manual E-Stop button installed.

RE: The ignition switch?

What will the e-stop "stop"? Technically, the computer controls the various engine functions, such as the fuel pump, the ignition timing, the throttle, and the starter solenoid, among others. Which are you looking to cut off? Selecting neutral is the best bet in terms of allowing everything else to continue to function, but I'm not sure what you want to have happen.

RE: The ignition switch?

Every OE that I know has used the ECM to command starter functionality for 20+ years, the switch just sends the driver request to the ECM.

E-stops allow drivers to kill vehicle power during runaways, fires, etc. On a test car they’re usually the big red mushroom in the ugly lil box velcroed or otherwise poorly fastened to the top of the dash. On a racecar they’re usually installed with a bit more pride.

RE: The ignition switch?

I do not know the details of that particular vehicle - you would have to obtain the factory service manual and dig through wiring diagrams to see where the circuits for the ignition switch go. But ...

If any vehicle in that generation ever had a factory trim level with pushbutton start, or if there was ever a factory option for remote-start via the key fob, or if it ever had a factory-equipped immobiliser-type alarm system, you can be certain that all engine starting and running functions are commanded through the ECU, even on the trim-level versions that don't have those features.

RE: The ignition switch?

(OP)
The E-Stop would be in series with the power supply to the coils, I'm guessing they are controlled by the ECU grounding them? Too many cases of unintended acceleration, all fully computerized vehicles need an E-Stop button. So do all Max 8 aircraft, since all sources tell me the plane still has control cables. If ignition is commanded by the computer system that means the only control on some older vehicles that the driver has is the steering wheel.

RE: The ignition switch?

Too many? Most every case of unintended acceleration is due to the driver pushing the accelerator pedal. One case was a pedal trapped by a floor mat; the same car with the same mat stuck the same way was stopped a day or so before by using the brakes.

E-stops only work when the user isn't panicked - panic appears to be the case for every driver in every unintended acceleration accident.

Anyway - it's easier to pull power from the fuel pump.

RE: The ignition switch?

(OP)
https://www.carproblemzoo.com/honda/cr-v/car-accel...

Maybe some acceleration problems are caused by incapable drivers. But with fly by wire and total computerized control of every system in a vehicle now, it is possible to have a runaway. Many things can cause that with electronic systems. Most newer vehicles have full on board diagnostics by radio capabilities, works similar to onstar and probably not well known, that opens them up to hacking and remote control.
In a runaway condition, how can you turn it off if the computer controls everything? The accelerator or throttle, the brakes ABS, now the electronic steering, the full electrically actuated valve body with no mechanical linkage to the manual valve or park pawl, the parking brake, and of course the ignition switch system. In such cases your basically in for the ride in an autonomously controlled vehicle, that you think your in control of via video game joy sticks of sorts.

Hand full of reports?, like everyone with some car problem is going to go on line to report it. Gosh most of them don't even get reported to the manufacture, check the above link.

Some new learning in this.
https://www.youtube.com/watch?v=NCTf7wT5WR0

Fuel pump power I thought of that, but then it can have a small run on time, maybe just use a DPST and pull both.

I use to have a vehicle that did an unintended acceleration deal, it had a little linkage problem, I'd just turn off the ignition switch if it wouldn't clear right away, but then some of us are not the panic types.

RE: The ignition switch?

The movie "Christine" is a documentary.

RE: The ignition switch?

Quote (enginesrus)

The E-Stop would be in series with the power supply to the coils, I'm guessing they are controlled by the ECU grounding them? Too many cases of unintended acceleration, all fully computerized vehicles need an E-Stop button. So do all Max 8 aircraft, since all sources tell me the plane still has control cables. . .
What a great idea - E-Stops in aircraft. Think of the lives that could be saved!

je suis charlie

RE: The ignition switch?

FMEA isn't simple.

RE: The ignition switch?

(OP)
The E-Stop in an aircraft is to get all automation out of the loop. So it does not interfere with a pilot trying to save his plane that a computer has hijacked. Not to E-Stop the engines.
If those Max 8's had that hundreds of people would be alive.

RE: The ignition switch?

Quote:

If those Max 8's had that hundreds of people would be alive.

Not necessarily; the pilots would still have needed to know what the MCAS system was doing; moreover, EVERYTHING in the controls have some level of automation, even if it's not FBW. An FBW Airbus would fall out of the sky if you E-stopped its automation system since all controls would die.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: The ignition switch?

That's the puzzle for Ethiopian. The entire MCAS operation was detailed in the Lion Air Preliminary report that was issued on or about the same day Ethiopian took possession of their accident airplane; also at the same time the FAA Emergency AD and the new FCOM pages from Boeing were issued to Ethiopian. Yet, 5 months later when their crash happened, neither pilot had been through any training on the matter. It's been 21 months since the typical final report issue date for Ethiopia to do so.

RE: The ignition switch?

(OP)
The whole idea of an E-stop in the plane would be to get rid of MCAS and any other computer trying to hijack the plane. Yeah Airbus and all the other full flyby wire tubular coffins, at first there were tons of fatality's with them. Any place that electronics has full authority over control there is a chance of some problem. 5G is concerning many pilots.

RE: The ignition switch?

Maybe you should consider walking...

RE: The ignition switch?

Walking? I read about a guy who did that and found himself hauled into the trees by a python. http://news.bbc.co.uk/2/hi/africa/7999909.stm

This doesn't touch on the dangers of drop bears, the victims of which are never found.

RE: The ignition switch?

Quote:

The whole idea of an E-stop in the plane would be to get rid of MCAS and any other computer trying to hijack the plane.

That's a remedy possibly worse than the disease, in most cases. If the designers could get to the point of identifying all possible cases of "hijack" the MCAS incident wouldn't have occurred in the first place. There are almost always unintended consequences for any drastic actions like this. MCAS is a teensy, teensy, part of millions of lines of code. Adding an E-stop means likely years of regression and safety testing, and they cheated on the testing as it is.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: The ignition switch?

Wasn't MCAS stuffed into some old 8-bit processor and had to be kept very simple so it would fit?

Would this plane e-stop have to latch off until some higher power re-engage the systems? One of the crashed flights, the pilots turned off the trim system which disables all electrical control over the stabilizer (just like this magical E-stop would do), but they also put flew the plane too fast with it so far out of trim that they couldn't hold it in the air. So, they decided to turn the trim system back on. What the pilots did amounts to the same thing as pressing this magical save the plane E-stop and then deciding to pull it back out again.

RE: The ignition switch?

I'm sure the disasters forum has a MCAS/737 crash thread. The number of failures outside of MCAS operation were mind numbing, but Boeing has become the central pinata.

RE: The ignition switch?

There is/was thread815-487065: Boeing 737 Max8 Aircraft Crashes and Investigations [Part 9]

However, the OP was asking a more general question, which included Toyota's SUA problem. On the Prius, disabling all computer enhancements means stopping the SUA, but also killing the ABS and power steering. Asking someone to have the presence of mind to manually pump the brakes in an SUA scenario is a long reach.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: The ignition switch?

(OP)
This thread is all about a computer hijacking a vehicle, and how to regain control of that vehicle (air or ground). It is not a joke or something to joke about, it is something that needs serious thought of how to do it. Its all funny until you or a loved one are in a vehicle that has this happen.

RE: The ignition switch?

In the vehicle that started the focus on SUA for Toyota, the initial incident driver shoved on the brakes and pulled to the side of the road and then shifted to neutral. It's what I did both times (two different vehicles) a conventional throttle stuck WOT in passing situations. It was also the case that my fully manual car became difficult to stop because GM decided to run a brake line in a place that wasn't possible to inspect but was a place where road salt could cut through - but without an isolation valve to keep the brake fluid from bleeding out. Good job GM.

RE: The ignition switch?

eru,

I don't see anyone particularly laughing here, but I don't see a kill switch as a panacea, because of the unintended consequences. You, or any of the others in the thread, might know and expect what might happen when a car's electronics is killed, but your "loved ones," would they know what to expect and how to respond? Will they be like the 737MAX crew that was unable to control the plane with MCAS turned off? And note, that was ONLY the MCAS being disengaged. Imagine the tumult if all computerized systems were turned off? Would you trust an aircrew that hasn't been flying by the seats of their pants to manually fly a plane with you on board?

And what happens if the kill switch gets accidentally engaged in the middle of a critical maneuver? Will your loved ones know exactly what to do because not only is acceleration turned off, but so is power steering and braking. And note that not all scenarios are served by having no gas; unless EVERYONE else on the road is equally careful, you're likely to be killed by someone who was glancing at their text messages and failed to notice that you're stopped dead in the water.

By all accounts, both the 737MAX's and Toyota's code was rife with errors, bugs, and bad coding practices. THAT is what needs to be concentrated on, writing GOOD code, particularly in the case of Toyota, whose industry has a coding standard and their programmers completely ignored it and Toyota's management lied about complying with it. Concurrently, we need to have good code checking beyond what people at Toyota didn't even bother checking. Their "mission critical" variables had ZERO redundancy, so ANY mishap could potentially change the variables and FUBAR everything, along with the fact that their software stacks were constantly in danger of overflowing, because they under-designed them and just assumed that everything would be hunky-dory, with doing the extensive testing to prove it.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: The ignition switch?

Ha. I can answer what happens when the kill-switch inadvertently operates. GM built a kill switch into the same car with the failed brake line. Cruising down the highway the engine drops dead. Thankfully I have a clutch pedal to eliminate engine braking, but still get to cut across 3 lanes of high speed traffic as my car slowed on the gentle uphill. It took a dealer mechanic two days to figure it out - and return the car to me with a massive oil leak from screwing with the distributor, but not replacing the distributor o-ring. It turned out no changes to the distributor were required; the cause was a corroded ground under the ignition module that hangs out under the cap. Since the dealer didn't tell me what they did I got to discover that corrosion problem on my own later. Eventually I just kept the screwdriver to remove the module and some sandpaper in the car; it was "fixed" several more times that I owned the car. Here's a hint GM - steel rivets in contact with aluminum is a problem.

RE: The ignition switch?

Quote:

but your "loved ones," would they know what to expect and how to respond?....THAT is what needs to be concentrated on, writing GOOD code

Agreed on both points. Probably the best example arguing against kill switches is the famous GM ignition switch debacle from ~10 years ago. Most of the wrecks behind that recall didn't involve the steering column actually locking, just loss of engine power. Not to deride anyone but many folks simply dont react well to emergencies, both their minds and bodies freeze up in new situations. When I taught driver's training in the military (often to city folks who had never driven a lawnmower much less a large military vehicle) we intentionally had new drivers drift vehicles on ice and dirt, pulled parking or trailer brakes randomly, and set up other scenarios where they would be forced to think and react. With a bit of training anyone can become a really good driver, unfortunately stateside our system is designed to crank out "steering wheel holders."

As to software quality, I never gave that much thought until a sibling that is a computer scientist borrowed my small collection of engineering quality texts and returned with a rant about poor quality in the software industry. His experience as a programmer was that they dont give nearly the diligence to ensure quality through testing that I have experienced as a ME. Disclaimer: I'm an automotive hardware guy, he's an OS programmer so about as far apart as possible in terms of role and industry.

RE: The ignition switch?

It's an interesting contrast - to ensure that the ignition remained in run-mode the correct choice would be an interlock to overcome like there is to start the car in the first place (though that is to manage the anti-theft device.) But an interlock to prevent inadvertent shutdown is exactly how the 3-second push to shut off the "out of control" Toyota with the trapped pedal was intended to work.

RE: The ignition switch?

But, how many people actually knew about that feature, or remember, or remember during a panic situation? A feature that 99.9% of the users will never use is a problematic safety feature

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: The ignition switch?

It sucks to have a loaner car have an emergency situation within the first few hours of operation. The best thing was the dealer that loaned out that car got sued out of existence - because they had been told the floor mat caused unexpected acceleration and they put it back to do it again. Still it's curious that a cop panicked and didn't put the transmission in neutral, but no one teaches people anything about how the devices they use and depend on actually work anymore.

RE: The ignition switch?

(OP)
If you read the info I posted about the CR-V's some tried to put it in neutral, it didn't matter, and with many cars, may not work anyway if there is no manual valve connection to the shift control. All newer valve bodies are now electronically controlled that means you move a joy stick to shift and the PCM TCM or which ever does the shifting. There is no jamming it in park no nothing. All your driver controls are pretty much like a video game joy stick, with no mechanical linkages. So in these situations how do you regain control? There is no way to shut it down, from the drivers seat. You have no access to the wiring under the hood.

You would think the first thing the cop would try is to shut off the ignition switch. It is evident that he had no way to shut it down.

RE: The ignition switch?

I would think the cop would do what the last person to drive the same car with the same problem did before he came back and complained to the dealer. The cop did have a way to shut it down but the dealer didn't tell him and he didn't read the manual (probably removed by the dealer).

Only one claim that it would not go into neutral from anything but Park (shouldn't they have to use Reverse gear first?) - from someone no doubt panicked.

Quite worrisome - claiming that the CR-V has an emergency brake. If used this will typically leave the car uncontrollable. Most cars have a parking brake.

Anyway - based on those claims, get rid of the CR-V immediately. Most troubling "I was also unable to stop my car."

I wonder if that car is still driving around.

I assume you have had time to put in the cut-out switch on the fuel pump so you have no problems anymore.

RE: The ignition switch?

ecu controlling starter - I hadn't thought of that, but my 03 Regal was definately hard-wired fron ign switch through the neutral safety switch to the solenoid. The wire is probably 10 gauge.

My 2016 Impala Limited is definately ecu controlled, because I can twitch the key and it will crank for several seconds until the engine catches. And this car is pretty much the same as my 2011 Impala, because the "Limited" was the old series continued in production while they built a new Impala at the same time. Strange, but they did something like that with the Malibus for a while...

With electric power steering assist, you sure don't want all power cut off. And power brakes are only good for one or two applications before you exhaust the stored vacuum. Of course the abs needs power, but you can still stop without it.
Of course, with the older hydraulic power steering you need the engine turning for hydraulic pressure. Then there are all the cars using hydraulic brake boost, I wonder how many applications they can do with engine off?

Then, if things go badly and you do hit something - no power means no airbags. Crap. Yes, if they are installed I want them to have some chance of functioning.
But shifting by wire does make me nervous. All of my cars since the 03 Regal (and including it) have had ECU control of shifting, but certainly there is physical valving in the trans that is connected to the shifter.
The ecu can do whatever it wants, but if I put it in neutral, the ecu can't cause the trans to transmit power - I think.
Now I want to look up the design of the Impala's trans and verify that...
Anyway - an electric disconnect will be needed in my funky project hotrod when I take it on the track, but really not suitable for a modern passenger car.
As an anti-theft device, a stealthy switch in the fuel pump power lead could be useful!




Jay Maechtlen
http://www.laserpubs.com/techcomm

RE: The ignition switch?

I have a late model car with a feature getting to be rare. The leftmost pedal works a little hydraulic cylinder that mechanically pushes friction plates out of engagement when pressed with no ECU intervention, and a lever in the middle of the instrument panel works a couple of cables that push and pull a mechanical gizmocontraption that engages the gear that I want, with no ECU intervention possible.

glasses

RE: The ignition switch?

I waited to get an actual manual for my current GTI as the DSG is basically the enforced preference nowadays. I don't care if it's 'better' by any objective metric, it fails on other subjective levels. flame

RE: The ignition switch?

(OP)
My use of the word emergency brake is the same as parking brake, others call them a (BREAK)these days. In the old days it was called an emergency brake I think, it is a manner of speech. I studied the manual for this car and it does have a manual shift cable. So hope park and neutral would work. Unless the shifter is locked out some how, since some folks mentioned they could not move the shifter. ABS can and could eliminate all brake function. To install a fuel cutout switch it would require too much as far as the wire loom goes or interior. Much easier to trace from ignition coils.

RE: The ignition switch?

(OP)
Thank you for those links. I'll have to check the wire diagram. I thought about the relay and fuse before hand. I do not want to tear into the fuse box, or cut a factory wire in the main wire loom. I'll check for the
cutout switch that would be the best choice.

RE: The ignition switch?

How were you going to change the ignition harness without cutting a wire? Anyway, I'm sure you can get compatible connectors and just make a jumper to insert.

RE: The ignition switch?

(OP)
After the fuel pump fuse, there is a T connection to the PCM, the question is can that feed power to the relay during a fault? If so the fuse is bypassed. No such thing as schematics for all the secret black boxes spread through out all the computerized cars these days. Sorry I do miss the vacuum tube days so much, for ease of repairs.

RE: The ignition switch?

The only way for the ECU to monitor whether the fuel pump is getting power and monitor the integrity of the circuit is for the status to be fed back as an input, and that means there needs to be a wire somewhere. This is how it is capable of generating fault codes such as "fuel pump circuit open or short to ground", etc.

An input to an ECU is not electronically capable of being an output. (A connection to the gate terminal of a transistor is not electronically capable of delivering output power.) It will be protected inside the ECU.

RE: The ignition switch?

Quote:

An input to an ECU is not electronically capable of being an output.

Not necessarily; given the high noise environment of the engine compartment, low impedance drivers will tend to drive sufficient current to minimize noise, so there may be sufficient drive for an additional load. That said, after the additional load is added, the noise immunity might be severely degraded.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: The ignition switch?

I would be more convinced if the video was available. I can wire a car to act just like that too. It appears nothing ever happened; perhaps the Best Attorney is fishing for clients.

RE: The ignition switch?

(OP)
It helps prove the authority the in car computers have over such things as ignition switch, and throttle. The much newer models control everything, again that is everything. You are along for the ride if something glitches or is hacked. I am lost at the lack of concern of manufactures to install some sort of emergency stop system, just in case. Just like they should have fail safe measures for over pressure of airbag inflators.
Just makes a person wonder what is the deal?

RE: The ignition switch?

2
No-one here cares "what is the deal". Go somewhere else if you just want to rant about how scary new vehicles are.

I opened the link expecting something interesting but found a description of a truck where the brakes, steering and shifting to neutral were all working.

RE: The ignition switch?

(OP)
I guess that last comment explains it all.

RE: The ignition switch?

Tie a string to the fuel pump fuse. One pull and you'll be safe. Like yanking a tooth.

RE: The ignition switch?

The market proves that this is not a concern for the majority of car buyers, since they care about the price point, styling, and performance features, rather than paying, say, a 20% premium for a possibility of a miniscule probability occurrence. Cars are designed to achieve tolerable risk, not absolute safety; everything in the car costs money, and testing for tiny probability failures incurs lots of additional costs. A car that provides absolute safety likely incurs more cost than anyone, even you, might be willing to pay. Not to mention all the unintended consequences; the heavier the portion of cutouts and safety switches, etc., the more likely there will be failures in those features that result in fatal accidents when none should have occurred at all.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers Entire Forum list http://www.eng-tips.com/forumlist.cfm

RE: The ignition switch?

Besides - we have all these secondary safety devices. When the electronic throttle goes wide open, the ignition can't be switched off, the transmission can't be forced to neutral and the brakes are cooked and useless - there are always the airbags - oh wait . . . . surprise

je suis charlie

RE: The ignition switch?

rofl

"Schiefgehen wird, was schiefgehen kann" - das Murphygesetz

RE: The ignition switch?

Quote (IRStuff)

Cars are designed to achieve tolerable risk, not absolute safety

Lack of understanding of this (accurate) statement is, I think, the reason we have a bunch of these 'but what about an e stop in a car' threads.

RE: The ignition switch?

There is no such thing as "absolute safety". If applying a countermeasure to an identified risk requires adding more switches, sensors, wiring, devices, logic, and so forth, then each of those additional elements adds their own elements of risks or failures, and sometimes the entire concept of the countermeasure itself can lead to risks ... the old "unintended consequences".

Let's s'pose that one were to install the big red button that switches off everything in the car, hard-wired, with no computer intervention possible.

What happens if someone accidentally presses it while travelling at 130 km/h on the motorway? What if a passenger accidentally hits it? If you put it in a place where the passenger can't reach it, what happens if a situation arises where the passenger really is warranted in shutting the car down but can't reach it? There IS NO perfect solution because what might be "safer" given one set of circumstances either doesn't solve the problem or makes matters worse given a different set of circumstances.

If you want to get involved in FMEA, what if the wiring to the switch fails? What if the contacts remain open? What if the contacts weld closed? What if the wire shorts-to-B+ or shorts-to-ground or open-circuits? YES these are already existing line items for all sorts of existing components in the vehicle ... you've just added more, by adding another switch and more circuits and more relays and more wiring.

What, exactly, do you have that big red button switch off? If you switch off EVERYthing, you just switched off power steering (it's generally electrically operated nowadays - and even if not, you just switched off the engine and therefore the power steering pump), and you just switched off the power to the crash sensors and the airbag controller.

Hmmm, that sounds a lot like the problem GM had with the Chevrolet Cobalt ignition switches. No big red button, but that was a traditional old-skool hard-wired ignition switch that, when turned off, turned off everything in the car including the airbag module. GM's problem was that the location and orientation of the switch and the force required to actuate it made it prone to being accidentally bumped and switched off while in motion.

Okay, so let's maybe not switch off the airbag module. Does that mean the airbag system has to stay active when the car is switched off? What happens if I get hit while stopped in my car and I've stopped the engine because the traffic has stopped - should the airbag system stay on? If yes - how long? Is the airbag system to remain in wait while the car is parked for three weeks at an airport parking lot?

If the driver switches off the ignition switch while the car is in motion, it's pretty easy nowadays (with electronic controls in the form of a suitably programmed "body control module") to arrange for ABS and electric power steering and lighting circuits and airbags etc to remain powered up until there is suitable evidence via other sensor signals that these systems are not needed.

FMEA is a real thing. The auto manufacturers do it. They are not perfect nor is anyone else, and you can identify situations in which there is no perfect solution but you have to weigh the probability of event X and its consequences against the probability of event Y and that event's consequences.

No, a '63 Ford Falcon didn't have a lot of these things. It didn't have ABS or airbags or electric power steering. You didn't have to worry about when to switch something on or off if it didn't exist in the first place.

In terms of safety I will take my odds in a crash in my modern small car over what would happen in a '63 Falcon ANY day. It may not be perfect ... nothing is ... but we are in a whole lot better position now than we were then, in terms of occupant protection.

RE: The ignition switch?

When we introduced ABS the FMEA was taken very seriously, and the DVP of tests was extensive and pursued thoroughly. One line item was - what happens if you fit a non ABS brake rotor (no tone wheel) to an ABS car? The test driver, who was a bit too clever, started at 10 kph, 20 kph, 30 kph, 40 kph. No problem with full braking.

At 50 kph the car spun around and almost rolled. Turns out the ABS was disabled below 10 kph, the software detected the slowest wheel as vehicle speed (this was the root cause of the problem) , and the ABS pickup was picking up the backs of the wheel studs (5) rather than the 40 or so teeth on the tone wheel that wasn't fitted. So at lower speeds he wasn't actually using the ABS, and was just manually modulating the brakes like usual to prevent a skid, subconsciously no doubt.

What he /should/ have noticed in an ideal world was that at 20 kph there was no ABS intervention. That was when the system stopped behaving as expected, which as Mr Feynman remarked, is when the investigation should start.



Cheers

Greg Locock


New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

RE: The ignition switch?

Sometimes the ecu will disable the electronic throttle on brake application.
That annoys people like me who sometimes want both applied for fine control or fast response.
I suspect that disabling throttle when braking at speed would be reasonable, in a way that would intercept /disable any possible cause of unintended acceleration.
(is it still 'sudden' after the first ten seconds?)

Jay Maechtlen
http://www.laserpubs.com/techcomm

RE: The ignition switch?

I know the throttle-cut on brake application was introduced when I had a VW with drive-by-wire. The way VW did it is that if the brake was applied first and then it received a throttle input, it accepted the throttle input (to allow the driver to match revs when downshifting a manual transmission), but it cut engine power output if the brake was applied while throttle was still being applied (which is the situation that would exist if a floor-mat was trapping the accelerator pedal, or if the accelerator pedal sensor failed in some manner). I think my current car (Fiat) is also like that - I know it still correctly allows a rev-match downshift - but I haven't tried what happens if the brake is applied while on throttle. In normal driving, it should never occur (it has certainly never bothered me). Rally drivers may beg to differ, but that's not who cars like this are set up for.

The best countermeasure against "unintended acceleration" of course is the third pedal ... I doubt if a case of unintended acceleration has ever been reported for a vehicle with a manual transmission. Drivers lacking the dexterity and co-ordination to use a clutch pedal won't even get the car to move. When I encounter unexpected slipperiness, shoving in the clutch to maximise lateral grip is instinctive.

RE: The ignition switch?

(OP)
Manual transmission is wonderful as long as there are no computer links to it, no solenoids or motors of any sort, that have any control over it.

RE: The ignition switch?

Quote (enginesrus)

Manual transmission is wonderful as long as there are no computer links to it, no solenoids or motors of any sort, that have any control over it.

Top of that list should be incompetent drivers.

je suis charlie

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close